ANSI/ASME B16.5 Flanges

  • Size: 1/2″ thru 24″ or custom size.
  • Material: Nickel Alloy,Hastelloy Alloy,Monel Alloy,Inconel Allo, Anti-Corrosion Resistant Alloy, Super-Alloy, Duplex Steel, Stainless steel, Titanium Alloy, Copper Alloy, Carbon Steel, Aluminium Steel, ect.
  • Standard: A WWA C207, ASME B16.5, DIN, BS, JIS, EN1092-1, ASME B16.47 and GOST/ГОСТ Standard, etc..
  • Approved by CE, RoHs, SGS, BV
  • Large stock with different sizes

ANSI/ASME B16.5 Flanges Solutions

ANSI/ASME B16.5 flanges are the most commonly used type of pipe flange in the world. They are used to connect two different pipes or two parts of a single pipe in order to allow gases, fluids and other materials to travel from one end of a pipe to the other. ANSI/ASME B16.5 flanges can be found on almost any piece of equipment that uses piping systems, such as boilers, cooling towers, pumps and more! The ANSI/ASME standard was developed by the American National Standards Institute (ANSI) and American Society of Mechanical Engineers (ASME) to help improve flange quality and to meet the needs of today’s industry. This standard explains how to design a flange, as well as how it should be manufactured. There are many different types of materials that can be used for flanges, including steel, stainless steel and titanium alloy.

Table of Contents

It will be helpful when you understand ANSI/ASME B16.5 flanges.

The ANSI/ASME standards were developed to help improve flange quality and ensure the safety of those who work with the piping systems. In order for flanges to be considered ANSI/ASME compliant there are certain requirements that need to be met:

  • Flanges must be designed using an approved software program or CAD system.
  • Flange dimensions must be within .02” tolerance on all diameters from pipe size to pipe size (for example 1-1/2″ schedule 80 pipe would have a .02″ tolerance).
  • The minimum bend radius for offset flanges is 8 times the diameter of the pipe being installed (for example if you are installing 1-1/2″ schedule 40 pipe then your minimum bend radius would be 16″).

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What are ANSI/ASME B16.5 flanges?

ANSI/ASME B16.5 Flanges are the circular or ring-shaped components that are used to connect pipes, valves, pumps and other devices. ANSI/ASME flanges are manufactured from carbon steel and alloy steel materials. They are used in pressure piping systems, high-temperature applications, marine services, and other corrosive environments. ANSI/ASME B16.5 Flanges are available in a wide range of sizes, materials and finishes. They can be manufactured with or without holes for fasteners or studs as well as any number of special features including:

  • Threaded connection;
  • Lapped joint connections (LJ) with gasket face seal arrangements;
  • Welding neck type flanges without integral stiffener rings.

Standard Specication For ASME B16.5 Flanges

  • Dimensions: ANSI B16.5, ANSI B16.47 Series A & B, MSS SP44, ASA, API-605, AWWA, Custom Drawings
  • Size: 1/2″ (15 NB) to 48″ (1200NB)
  • Class: 150 LBS, 300 LBS, 600 LBS, 900 LBS, 1500 LBS, 2500 LBS, DIN Standard ND-6,10, 16, 25, 40 Etc.
  • DIN: DIN2527, DIN2566, DIN2573, DIN2576, DIN2641, DIN2642, DIN2655, DIN2656, DIN2627, DIN2628, DIN2629,
  • DIN 2631, DIN2632, DIN2633, DIN2634, DIN2635, DIN2636,DIN2637, DIN2638, DIN2673
  • BS: BS4504 , BS4504, BS1560, BS10
  • Flange Face Type: Flate Face (FF), Raised Face (RF), Ring Type Joint (RTJ)

ASME B16.5 Pipe Flanges and Flanged Fittings: NPS 1/2 through NPS 24 Metric/Inch Standard covers pressure-temperature ratings, materials, dimensions, tolerances, marking, testing, and methods of designating openings for pipe flanges and flanged fittings. Included are:

  • (1) Flanges with rating class designations 150, 300, 400, 600, 900, and 1500 in sizes NPS 1/2 through NPS 24 and flanges with rating class designation 2500 in sizes NPS 1/2 through NPS 12, with requirements given in both metric and U.S. Customary units with diameter of bolts and flange bolt holes expressed in inch units;  
  • (2) Flanged fittings with rating class designation 150 and 300 in sizes NPS 1/2 through NPS 24, with requirements given in both metric and U.S. Customary units with diameter of bolts and flange bolt holes expressed in inch units;  
  • (3) Flanged fittings with rating class designation 400, 600, 900, and 1500 in sizes NPS 1/2 through NPS 24 and flanged fittings with rating class designation 2500 in sizes NPS 1/2 through NPS 12 that are acknowledged in Non-Mandatory Appendix E in which only U.S. Customary units are provided.  

B16.5 is limited to flanges and flanged fittings made from cast or forged materials, and blind flanges and certain reducing flanges made from cast, forged, or plate materials. Also included in this Standard are requirements and recommendations regarding flange bolting, flange gaskets, and flange joints. This Standard is to be used in conjunction with equipment described in other volumes of the ASME B16 Series of Standards as well as with other ASME standards, such as the Boiler and Pressure Vessel Code and the B31 Piping Codes.

What are the different types of ANSI/ASME B16.5 flanges?

Flanges are designed for joining purposes and widely used in various industries. There are different types of flanges available in the market which can be chosen according to the requirements of an application.

Slip-on flange

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Slip-on flanges (SO flanges) are slid over the pipe and welded (usually internally and externally) to provide strength and prevent leaks. Slip-on flanges are located at the low cost end of the scale and do not require high precision when cutting the pipe to a certain length. These SO flanges can sometimes have tabs or hubs and can be fabricated with holes to fit the pipe or tubing. This type of flange does not require welding because it can easily be removed if needed without damaging either pipe or flange itself.

Weld neck flange

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Weld neck flange has a smooth, round surface where the pipe is inserted. They are a very popular form of flange, owing to their simplicity and ease of use. Welded flanges are used in applications where high pressure is involved, but not necessarily high stress. The clamping force on this type of weld neck flange is applied in the direction of the weld seam (not perpendicular to it). A weld neck flange (also known as a high-hub flange and tapered hub flange) is a type of flange. There are two designs:

  • The first design has an internal ring that is welded to the base material. This allows for a smooth transition between the pipe and the flange, making it ideal for high-pressure applications.
  • The second design uses a split disc to create the seal. This design has no weld, which makes it less expensive than the first type of weld neck flange.

Long Weld Neck Flanges

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Long weld neck flanges, also known as long high neck flange or long neck butt weld flange compared with the weld neck flange, long neck butt weld flange neck is a straight tube and not a tapered involute tube, in the common flange, its structural strength is the best, in comparison, the price is more expensive. We can also make other sizes of long neck butt weld flanges according to customer requirements. Long high neck flange is actually an extended form of the necked butt weld flange. Flange neck slightly straight type, neck height taken 229mm (≤ DN100) or 305mm (> DN100). Long high neck flange in CLASS series pipe flange is often used, in the nominal size less than or equal to DN50 pipe flange with the cylinder body, the use of long high neck flange can also avoid the flange neck end wall thickness is too thin caused by welding difficulties. Long high neck flange features: neck height is higher, the stiffness of the flange, load-bearing capacity has improved. Long high neck flange and weld neck flange compared to the welding workload, high welding rod consumption, can not withstand high temperature and high pressure and repeated bending and temperature fluctuations, but the site installation is more convenient, can omit the welding seam shot rubbing process, more popular.

Blind flange

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A blind flange is a solid disc used to seal a pipe or form a stop. Similar to conventional flanges, blind flanges have mounting holes around the perimeter and gasket seals machined into the mating surface. The difference is that the blind flange does not have an opening for fluid to pass through. Instead, it is placed between two open flanges, thus blocking the flow through the pipe. This type of blocking is often used when adding another line to an existing pipeline or when adding a new valve. Blind flanges have the surface thickness of a flange, a matching surface type, and a similar bolting pattern. Blind flanges can also be used to seal nozzle openings on pressure vessels.

Lap joint flanges

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A lap joint flange is a two-component assembly that has a lap ring flange on the lap joint stub end. The lap joint stub end is then butt welded to the pipe and the flange ring can be rotated to align with the mating flange. This type of flange connection is particularly useful for large or difficult-to-adjust flanges. Stub end flanges or more commonly known as LJ flanges are used in conjunction with flanges. The lap joint stub end adapter is slipped through the flange and welded to the pipe.

Ring Type Joint Flanges

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The ring joint (RTJ) flange is essentially a machined metal ring with a deep groove on its surface. A metal RTJ gasket sits in the groove to seal the flange pair. This metal ring is compressed when the connecting bolts of the RTJ flange are tightened. This compression creates a leak-proof, tight-fitting seal on the pipe or connection. Typically, Ring type joint flanges have a convex face with a recess into the flange surface, but the convex face does not contain similar pressure as a welded neck convex flange.

Threaded Flanges

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The threaded flange design (also called “threaded flange”) uses threads to connect the flange to the pipe. The male thread is cut into the end of the pipe and the female thread is cut into the flange hole; the male threaded pipe is then screwed into the female threaded flange. This type of connection is typically used in conjunction with other types of flanges, such as buttweld and socketweld, in order to create a seal between two pipes or fittings. The threaded design allows for easy installation and removal while also providing long-term durability.

Socket Weld Flanges

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Socket welding flange is called (SW flange), the basic shape of socket flange is the same as the flat welding flange with neck. There is a socket in the bore of the flange, and the pipe is inserted into the socket and welded. Weld ring is welded on the back of the flange. The gap between the socket flange and the grass groove is prone to corrosion, which can be avoided if the seam is welded on the inside. The fatigue strength of the socket flange welded on the inside and outside is 5% greater than that of the flat weld flange, and the static strength is the same. When using this socket end flange, its inner diameter must match the inner diameter of the pipe. Socket flanges are only suitable for pipelines with a nominal diameter of 50 or less.

SAE Flanges

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The SAE flange is a high pressure flange. SAE flange is a part that connects the tube to the pipe. Connected to the end of the tube. sae flange with holes, can wear bolts, so that the two sae flange tightly connected. sae flange with a gasket between the seal. SAE flange joint (flange, joint) consists of a pair of SAE flange, a gasket and a number of bolts and nuts. The gasket is placed between the two SAE flange sealing surface, tighten the nut, the gasket surface pressure reaches a certain value after the deformation, and fill the sealing surface on the bump, so that the coupling is tight and does not leak. SAE flange joint is a removable joint. According to the connected parts can be divided into container SAE flange and pipe SAE flange. According to the structure type, there is a whole SAE flange, live sleeve SAE flange and thread SAE flange. The common overall SAE flange has flat welding SAE flange and butt welding SAE flange. Flat welding SAE flange rigidity is poor, suitable for pressure p ≤ 4MPa occasions; butt welding SAE flange also known as high neck SAE flange, rigid, suitable for higher pressure and temperature occasions. SAE flange sealing surface type there are three: plane type sealing surface, suitable for pressure is not high, medium non-toxic occasions; convex sealing surface, suitable for slightly higher pressure occasions; tongue and groove sealing surface, suitable for flammable, explosive, toxic media and pressure. The tongue and groove sealing surface is suitable for flammable, explosive, toxic media and high pressure applications. A gasket is a ring made of a material that can produce plastic deformation and has a certain strength. Most of the gaskets are cut from non-metallic sheets or made by professional factories according to specified dimensions, and are made of asbestos rubber sheet, asbestos sheet, polyethylene sheet, etc.; there are also metal clad gaskets made of thin metal sheets (white iron, stainless steel) wrapped with non-metallic materials such as asbestos; there is also a winding type gasket made of thin steel belt and asbestos belt together. Ordinary rubber gaskets are suitable for temperature below 120℃; asbestos rubber gaskets are suitable for temperature below 450℃ for water vapor, below 350℃ for oil and below 5MPa for pressure, for general corrosive media, the most commonly used is acid-resistant asbestos sheet. In high-pressure equipment and pipelines, lenticular or other shaped metal gaskets made of copper, aluminum, 10-gauge steel, or stainless steel are used. The contact width between the high-pressure gasket and the sealing surface is very narrow (line contact), and the processing finish of the sealing surface and the gasket is high. SAE flanges are divided into threaded connection (fillet connection) SAE flanges and welded SAE flanges. Low-pressure small diameter has a silk connection SAE flange, high-pressure and low-pressure large diameter are using welded SAE flange, different pressure SAE flange thickness and the diameter and number of connecting bolts are different.

Orifice Flanges

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Orifice flange installed in the closed pipe, according to the principle of throttling device, measuring liquid, gas and steam flow detection components. The standard orifice plate is a thin metal plate with a circular opening, the wall of the circular hole is at right angles to the front surface of the orifice plate, and the axis of the orifice plate is concentric with the axis of the pipe during installation. The orifice flange is mainly used to replace the standard pipe flange when the orifice plate or flow nozzle must be installed. The orifice flange comes with a pair of pressure take-off ports, eliminating the need for additional orifice plate supports or drilling holes in the pipe. The orifice plate is mounted by screws and is easily removable.

Expander Flange

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The expander flange looks like a welded neck flange, but it has a hub that expands to a larger size (one or two sizes). It is designed to transfer stress to the pipe, thus reducing the high stress concentration at the bottom of the flange. Used to increase the size of the pipe at the flange connection. It provides a convenient way to connect to equipment, pumps and valves if you have limited space or just need to connect to a larger pipe size. It can be used in place of flanges and reducers. Pressure ratings and dimensions are in accordance with ANSI/ASME B16.5. This flange has a convex face. The expander flange is also considered a cost effective alternative to using a separate reducer weld neck flange combination. Expander flanges are available in a variety of sizes and materials. We manufacture and supply expander flanges in different materials such as carbon steel, stainless steel, and alloy steel.

Tube Sheets

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The tube sheet, which is a round steel plate with a slightly larger hole drilled in it than the same outer diameter of the tube, is a round steel that plays a role in fixing the tube as well as sealing the medium in the heat exchanger. The tube will be welded into the fixed, to play such a role of a fitting. Tube sheet processing accuracy, especially the tube hole spacing and tube diameter tolerance, verticality, finish are greatly affect the above listed chemical equipment assembly and use performance.

Heat exchanger tube and tube sheet 5 kinds of connection structure form

Tube and tube plate connection, in the design of shell and tube heat exchanger, is a more important part of the structure. It is not only a large processing workload, and must make each connection in the operation of the equipment, to ensure that the medium without leakage and the ability to withstand media pressure. For the tube and tube plate connection structure form, there are three main, (1) expansion, (2) welding, (3) expansion welding combination. These forms in addition to the characteristics inherent in the structure itself, in the processing, production conditions, operating techniques have a certain relationship.

Expansion joint

Used in the case of leakage of media between the tube and shell will not cause adverse consequences, expansion of the structure is simple, easy to repair the tube. Due to the plastic deformation of the expansion joint at the end of the expansion joint, there is residual stress, as the temperature rises, the residual stress gradually disappears, so that the end of the tube to reduce the role of sealing and bonding. Therefore, this expansion joint structure, subject to certain restrictions on pressure and temperature. Generally applicable pressure P0 ≤ 4MPa, the limit of residual stress disappearance at the end of the tube temperature varies with the material, carbon steel, low alloy steel when the operating pressure is not high, the operating temperature can be up to 300 ℃. In order to improve the quality of expansion, the hardness of the tube sheet material requires higher than the hardness of the tube end, so as to ensure the strength and tightness of the expansion joint. For the roughness of the bonding surface, the size of the pore between the tube hole and the tube, the quality of the expanded pipe also has a certain impact, such as the bonding surface rough, can produce greater friction, expansion is not easy to pull off, if too smooth is easy to pull off, but not easy to produce leakage, the general roughness requirements for Ra12.5. In order to ensure that the bonding surface does not produce leakage phenomenon, in the bonding surface does not allow the existence of longitudinal groove marks. Pipe hole with light hole and ring groove hole two, the form of the hole and expansion strength, the expansion of the mouth by the pull-off force is small, can be used light hole, in the pull-off force is larger when the structure with ring groove can be used. Light hole structure for the material properties of the heat exchanger, the expansion depth of the tube plate thickness minus 3mm, when the thickness of the tube plate is greater than 50mm, the expansion depth e generally take 50mm, tube end extension length of 2-3mm. When the expansion joint, the tube end will be expanded into a conical shape, due to the role of flanging, can make the tube and tube plate combined more firmly, higher resistance to pull-off force. When the tube bundle is subjected to compressive stress, the structural form of flanging is not used. The purpose of slotting the pipe hole is similar to that of flanging the pipe mouth, mainly to improve the resistance to pull-off force and enhance the sealing. The structural form is to open a small circular slot in the pipe hole, the depth of the slot is generally 0.4-0.5mm, when the expansion, the pipe material is squeezed into the slot, so the medium is not easy to leak. The number of slots in the pipe hole depends on the thickness of the pipe plate, when the plate is less than 30mm, open a slot, the thickness of the plate ≥ 30mm, open two slots. The expansion depth is decided by full expansion type and non-expansion type, for the tube plate using not full expansion type, when the thickness of the tube plate is greater than 50mm, the expansion depth is still 50mm. Pipe plate for composite steel, slotted position in two cases, the cladding is thin, slotted position are on the base, such as thicker cladding, a slot can be opened in the compound layer, but not allowed to open the slot between the cladding and the base.


The welding of pipe and pipe plate is widely used at present, because the pipe hole does not need to be slotted, and the roughness of the pipe hole is not required, and the pipe end does not need to be annealed and polished, so it is easy to manufacture and process. Welded structure of high strength, strong resistance to pull off, when the welded part of the leakage, you can make up the welding, such as the need to exchange the tube, you can use a special tool to disassemble the welded leaky tube, but more convenient than the disassembly of the expansion tube. Tube and tube plate welding, the shear section of the weld should be no less than 1.25 times the section of the tube. Stainless steel tube and tube plate, generally using a welded structure, regardless of its pressure and temperature. In order to avoid fluid stagnation on the tube plate after parking, and to compensate for the special situation of pressure loss at the entrance of the tube, reduce the resistance of the orifice, the tube can be shrunk in a certain position inside the tube plate hole, but this structure welding technology requirements are high, generally need to use automatic argon arc welding machine, the quality can be guaranteed, in the welding process the orifice is easy to block, especially for small diameter tubes, in welding should draw attention to. Sometimes in order to reduce the welding stress, you can process a concave groove surface down at the orifice of the tube plate, the structure is generally used for stainless steel and tube plate welding. In the pipe hole around the groove, processing trouble, workload, in the current construction of the groove has been removed.

Expansion welding combination

For high pressure, strong permeability, or corrosive media on one side, in order to ensure that no leakage after contamination of the other side of the material, which requires absolute non-leakage of the connection between the tube and the tube plate, or in order to avoid the impact of vibration on the weld during shipment and operation, or to avoid the possibility of seam corrosion, etc. The structure of the expansion and welding combination, from the process of processing, there are several forms of expansion and then welding, welding and then expansion, welding and then expansion and paste expansion. Expand first and then weld, expand the tube before welding, can improve the performance of the weld fatigue resistance, because the expansion of the tube to avoid tightly on the tube plate hole wall, can prevent cracks in the welding. But in the expansion of the tube due to the use of lubricating oil and into the gap of the joint, the presence of these residual oil and air in the gap heat expansion and vaporization, in the process of welding the joint under the action of high temperature to generate gas, escaping from the welding surface, resulting in the weld pores, seriously affecting the quality of the weld, so these residual oil must be cleaned off before welding. First weld after expansion: the use of first weld after expansion can eliminate the above phenomenon, but the use of first weld after expansion may make the weld cracking during expansion. In order to prevent this phenomenon, in addition to the expansion of the operation is carefully controlled properly, in the end of the tube, that is, in the first slot from the surface of the tube plate distance to be considered larger, about 16mm, in the range of 10-12mm from the surface of the tube plate is not expanded to avoid damage to the weld when expanding the tube. The advantage of first welding and then expanding is that it is not necessary to clean up the oil residue after expanding the tube, but the requirements for the location of the expanded tube after welding are high, and it must be ensured that the expansion is not carried out within the range of 10-12mm, otherwise the weld is easily damaged. First expansion after welding or first welding after expansion, for the welding part: there is a difference between sealing welding and strength welding two forms of welding, for the expansion part, there is a difference between strength expansion and paste expansion. Such as expansion and sealing welding combined with the structure, is to expand the joint to withstand the force, and sealing welding to ensure the sealing. Seal welding height is generally 1-2mm, so as not to affect the strength of the expansion joint, but in the welding must be cleaned at the joint of oil. Strength welding and expansion (paste expansion) combined with the structure, is to weld to withstand the force, while the purpose of the paste expansion is only to eliminate the gap between the tube and the tube plate, in order to prevent the gap from having corrosive media erosion. After welding expansion and paste expansion: after welding expansion and paste expansion is generally used in the higher pressure heat transfer equipment, the welding part to strengthen the sealing welding, welding waist height using 2.8mm, expansion part to withstand the force, when the expansion failure, strengthening the sealing welding can play a role in bearing the force, paste expansion part to eliminate gap corrosion. Weld expansion of the structure in what conditions, using the first weld after expansion or expansion after welding, there is no uniform provisions, but generally tend to first weld after expansion is appropriate. At present, because of the manufacturing plant plus process, equipment conditions are different, are accustomed to the plant’s production methods.

Bore welding

Inner hole welding is the tube hole in the shell process side of the formation is butt structure, heat exchanger tube and its butt welding, need special welding equipment. Inner hole welding is the tube plate after processing and heat exchanger tube to form a butt weld form, to have special equipment, the welding gun from the tube plate side of the tube hole deep into the welding seam for welding (from the original cross-joint into a butt joint), optimize the stress state of the heat exchanger tube and tube plate connection, greatly reducing the edge stress. It is very practical for heat exchangers with stress corrosion, or interstitial corrosion media. However, bore welding requires a high and difficult level of welding technology, and the appearance of welding defects can not be repaired, which can lead to the scrapping of the entire heat exchanger. To ensure that the welding is qualified, it is necessary to strictly follow the construction process parameters for welding, testing, etc.

Explosive expansion joint

Tube and tube plate connection using explosive expansion method has been used in foreign countries, which is a new process developed in recent years, due to the use of explosive expansion plus sealing welding or strength welding methods, not only the connection strength, and expansion efficiency has been greatly improved. Explosive expansion without lubricating oil, no oil at the end of the pipe exists, there are great benefits to welding after expansion. Explosive expansion is the use of explosives, in a very short period of time, the tube in the role of high-pressure gas shock wave, deformation, so that the tube avoid firm tightly on the tube plate hole. Explosive expansion joint is suitable for thin-walled tubes, thick-walled small diameter tubes and large thickness of the expansion of the pipe plate. The advantage of explosive expansion is the resistance to pull off the force, the tube axial elongation and deformation is small, when the tube end of the tube leakage, in the mechanical expansion can not be repaired, the use of explosive expansion to repair the effect is very good.


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A nipoflange/weldoflange is a combination of a welded neck flange and a so-called welded stub table or joint stub table. On the main pipe side, a jacket is designed similar to a welded stub table. This means that the branch connection on the main pipe side is a welded connection.

Pad Flanges

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The pad flange is known as the studding outlet. The pad flange is a nozzle in the vessel that allows the shortest possible projection inside and outside the vessel. This is critical in certain applications where certain equipment is installed onto a vessel. Often, equipment operators and engineers need to see inside the vessel during certain reactions or mixing processes.

Plate Flanges

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A flat flange is a flat disc welded to the end of a pipe that allows the flange to be bolted to another pipe. It is often referred to as a flat flange, flat flange and flange cava, etc. Two flat flanges can be bolted together with a gasket in between and are commonly used for fuel and water pipelines.

Reducing Flanges

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Reducing flange is also known as reducer flange, its inner diameter size and the standard flange inner diameter size there is a certain difference. In engineering, when the use of standard flanges can not match with pipe fittings, pipe coupling, change to use the reducer flange.

Square Flanges

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Square flanges are used in hydraulic systems to connect piping to components or piping to piping. As the name implies, square flanges are square. According to different standards of different countries, the flanges have different pressure levels to meet their uses. Square flanges are generally used mostly in pipelines with nominal pressure less than or equal to 10.0 MPa and nominal diameter less than or equal to 40 mm. Square flange is generally used for pressure is not high but in which the medium is more corrosive pipeline, so this type of flange corrosion resistance, the material is mostly stainless steel.

Swivel Flanges

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Swivel flanges are also known as swivel ring flanges. A swivel ring flange is a two-piece flange that is widely used in offshore pipelines and offshore industrial applications. A swivel ring flange has a heavy-duty forged welded hub which is secured to a forged ring which can be rotated to act as a weld neck or a companion flange to another flange. In a swivel ring flange, the swivel ring is held in place by the weld hub, which in turn is held in place by the retaining ring. The outer ring of the swivel flange allows the inner ring to be rotated 360° from the center of the flange so that it can be quickly aligned with its mating standard flange to align with the bolt holes. This feature is critical for subsea pipeline operations and allows divers to align bolt holes more quickly and easily. Swivel flanges can be designed for any size and pressure class to meet any accepted flange specification and gasket, such as ASME B16.5 or MSS SP-44. Non-standard swivel ring flanges can also be designed to meet customer requirements for special applications, such as overwelding of the inner ring or PTFE coating of the flange surface.

Spectacle Blind Flanges

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The spectacle blind flange is named because it looks like an “8” type blind plate. Used to isolate or connect piping systems. The spectacle blind is a steel plate with fixed thickness divided into two discs. Two discs are connected by flat steel, one of which is a solid disc, the other is a hollow ring, and its inner diameter is the same as that of the flange. It is usually used on pipelines with large pipe diameters. At ordinary times, one end of the flange occupies the space to keep the pipeline unblocked. If necessary, it is replaced with a fig 8 blind with the same thickness at the other end to cut off the pipeline. Avoid the forced expansion of pipelines due to temporary replacement of other blind plates, which will affect the whole system.

Flange face type

Flange face is a requirement for the easing of a joint. It can be used to create an outward bend in a flange which will allow for more movement and expansion in the direction of the bend. This type of joint also helps to reduce stress on the material being joined by allowing it to move freely when there is pressure applied.

Raised face

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A raised face (RF) is a feature of the flange that provides space for pipe joint, gasket and gland installation.

Flat face

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A flat or planar surface provides the most direct contact between two mating flanges because there are no gaps in their abutting surfaces, but there is little room for adjustment or tolerance error between them, so they are often used when precise alignment is needed between two components on a machine or device.

Ring type joint

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Ring type joints are circular in shape and have a high tensile strength. They are used in heavy duty applications where high amounts of tension or compression forces need to be handled. These types of joints are mainly used for large diameter pipes, such as those found in the oil and gas industry.

Tongue and groove

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Tongue and groove joints are a type of joint that interlocks two or more sections of a product. These joints are used in the construction industry, furniture industry, and many other places where wooden materials need to be secured together.

Advantages and Disadvantages of Flanges

Advantages of flanges: they’re used to join pipes together and are a great way to make a pipe connection with no leaks. You can use them for almost any type of pipe, including alloy steel, titanium steel, copper and stainless steel. they come in many different sizes and shapes, so it’s easy to find one that fits your specific application. Disadvantages of flanges: flanges are expensive (usually around $40-$50 each). However, if you buy them in bulk quantities (a lot), then this cost will be reduced significantly.

Material of ANSI/ASME B16.5 Flanges

ANSI/ASME B16.5 flanges are manufactured from carbon steel, alloy steel, stainless steel, nickel alloy and other materials. These are produced in various sizes, shapes and materials according to the needs of customers.

  • Stainless Steel ANSI/ASME B16.5 Flanges: ASTM A 182, A 240 F 304, 304L, 304H, 316, 316L, 316Ti, 310, 310S, 321, 321H, 317, 347, 347H, 904L
  • Duplex & Super Duplex Steel ANSI/ASME B16.5 Flanges: ASTM / ASME A/SA 182 F 44, F 45, F51, F 53, F 55, F 60, F 61
  • Carbon Steel ANSI/ASME B16.5 Flanges: ASTM / ASME A/SA 105 ASTM / ASME A 350 , ASTM A 181 LF 2 / A516 Gr.70 A36, A694 F42, F46, F52, F60, F65, F706
  • Low Temperature Carbon Steel ANSI/ASME B16.5 Flanges Flanges: ASTM A350, LF2, LF3
  • Alloy Steel ANSI/ASME B16.5 Flanges: ASTM / ASME A/SA 182 & A 387 F1, F5, F9, F11, F12, F22, F91
  • Copper Alloy Steel ANSI/ASME B16.5 Flanges: ASTM SB 61 , SB62 , SB151 , SB152 UNS No. C 70600 (Cu-Ni 90/10), C71500 (Cu-Ni 70/30), UNS No. C 10100, 10200, 10300, 10800, 12000, 12200
  • Nickel Alloy ANSI/ASME B16.5 Flanges: ASTM SB564, SB160, SB472, SB162 Nickel 200 (UNS No. N02200), Nickel 201 (UNS No. N02201), Monel 400 (UNS No. N04400), Monel 500 (UNS No. N05500), Inconel 800 (UNS No. N08800), Inconel 825 (UNS No. N08825), Inconel 600 (UNS No. N06600), Inconel 625 (UNS No. N06625), Inconel 601 (UNS No. N06601), Hastelloy C 276 (UNS No. N10276), Alloy 20 (UNS No. N08020)

Pressure class of flanges

  • Class 150: This pressure class is used for pressures up to 7,500 psi/512 bar. These flanges are required for temperatures up to 450℉ (232℃).
  • Class 300: This pressure class is used for pressures up to 10,000 psi/690 bar. These flanges are required for temperatures up to 600℉ (315℃).
  • Class 600: This pressure class is used for pressures up to 15,000 psi/1000 bar. These flanges are required for temperatures up to 750℉ (399℃).
  • Class 900: This pressure class is used for pressures greater than 20,000 but less than 25,000 psi/1530 but less than 1883 bar. They require higher temperature limits than the previous three classes of flanges because they must be heated during manufacturing process.

Size of flanges

Common flanges are those with diameters greater than 8″ because there is not a significant cost savings to be gained by the use of a forged flange. The cost of forging a flange is proportional to the diameter and surface area. This means that a large diameter flange will be much more expensive than a smaller diameter flange. The largest common size for forged flanges is 8 inches in diameter, but smaller sizes can also be forged. For example, an inch-and-a-half sized pipe can have many different types of fittings made: pressure relief valves, check valves, manual drain cocks, gate valves, butterfly valves and pneumatic actuators just to name a few. The advantages of using forged fittings over cast or machined parts include: better quality control; higher resistance to corrosion; longer life expectancy; lower weight per square inch than other materials like cast iron or steel which makes them ideal for high pressure applications where weight reduction improves efficiency; less maintenance costs since there are no seams where dirt could collect like in machined parts or castings with welded seams (which require grinding away). The size of the flange can be determined by measuring across the inside diameter of the flange, from edge to edge. To do so, you will need a ruler and a pen or pencil. You will also want to make sure that you have enough space to easily measure across the inside diameter of your chosen part. Flanges are most commonly measured in inches, but some manufacturers may use millimeters for their measurements instead. If you have trouble understanding how wide or thick your particular flange is, don’t hesitate to ask someone more familiar with their dimensions! The bore is the inside diameter of the flange, which is typically one of two types: full face or raised face. Raised Face – The raised face flange has two surfaces and is used when there is not enough room for a full face flange. The first surface, called “face”, provides flatness and smoothness to the mating surface during assembly. This type of flange allows for more tolerance than a standard design because it can rotate slightly with respect to its mounting surface, resulting in reduced stress on fasteners that secure it in place. Full Face – A full-face flange has three surfaces: one flat side (known as “face”), another flat side that acts as an opposite from which bolts may be installed (known as “heel”), plus a concave end where fasteners are inserted into corresponding holes along its length (called “neck” or “belly”). Full face refers to a completely flat surface; raised face refers to a surface with a ridge around it. In order to know what flange you need, you need to know the diameter of your pipe. If you have a raised face, then you will use it for pipes with a smaller diameter than the flange. For example, if your pipe is 1 inch and your flange is size 8, then you would use a raised face flange because it has an opening of 7/8” or 0.875 inches (the difference between two numbers that are multiplied together: 1/2 = .5). With this information in mind we can see why our example above was incorrect; A 1 inch pipe should not be used with an 8 inch flange! When it comes to flange size, the 2″ raised face flange is by far the most common. This type of flange allows for a wide range of sizes, including 1″, 1-1/2″, 2″, 3″ and 4″. The next most popular is an inverted or blind flange which comes in four widths: 1″, 2″, 3″ and 4″. Other types include butterfly (used primarily on gas stations), butt welded (which can be used as an alternative when welding would be more expensive than other methods), tee configurations (for joining pipes together), slip (for use with hoses) and threaded pipe nipples (to connect threaded pipes).

Dimension of ANSI/ASME B16.5 Flanges

Flanges are standardized according to publications of ASME, MSS, API and other organizations. Pipe flange sizes range from 1/2″ to 24″ and classs from 150 to 2500. ANSI/ASME B16.5 flanges dimensions are standardized in terms of diameter, wall thickness, and bolt circle. Bolt circle is the diameter of the circle where bolts are placed on a flange to form an interference fit with mating pipe ends. The diameter of ANSI/ASME B16.5 flanges is measured with respect to a reference plane that is perpendicular to the flow stream and lies midway between edges or bends in each side wall of the flange face.

ANSI/ASME B16.5 Class 150 Forged Flanges

  20221129002544 34178 - ANSI/ASME B16.5 Flanges

Nominal Size Outside Diameter Min. Thickness RF Dia. No. of Bolt Holes Diameter of Holes Bolt Circle SO Bore ID WN Bore ID Dia. Hub Base Dia. of Hub Top SO LTH WN LTH
(OD) (T) (R) (BC) (SB) (WB) (HB) (HT) (SL) (WL)
1⁄2 3.5 0.38 1.38 4 0.62 2.38 0.88 0.62 1.19 0.84 0.56 1.81
3⁄4 3.88 0.44 1.69 4 0.62 2.75 1.09 0.82 1.5 1.05 0.56 2
1 4.25 0.5 2 4 0.62 3.12 1.36 1.05 1.94 1.32 0.62 2.12
11⁄4 4.62 0.56 2.5 4 0.62 3.5 1.7 1.38 2.31 1.66 0.75 2.19
11⁄2 5 0.62 2.88 4 0.62 3.88 1.95 1.61 2.56 1.9 0.81 2.38
2 6 0.69 3.62 4 0.75 4.75 2.44 2.07 3.06 2.38 0.94 2.44
21⁄2 7 0.81 4.12 4 0.75 5.5 2.94 2.47 3.56 2.88 1.06 2.69
3 7.5 0.88 5 4 0.75 6 3.57 3.07 4.25 3.5 1.12 2.69
31⁄2 8.5 0.88 5.5 8 0.75 7 4.07 3.55 4.81 4 1.19 2.75
4 9 0.88 6.19 8 0.75 7.5 4.57 4.03 5.31 4.5 1.25 2.94
5 10 0.88 7.31 8 0.88 8.5 5.66 5.05 6.44 5.56 1.38 3.44
6 11 0.94 8.5 8 0.88 9.5 6.72 6.07 7.56 6.63 1.5 3.44
8 13.5 1.06 10.62 8 0.88 11.75 8.72 7.98 9.69 8.63 1.69 3.94
10 16 1.12 12.75 12 1 14.25 10.88 10.02 12 10.75 1.88 3.94
12 19 1.19 15 12 1 17 12.88 12 14.38 12.75 2.12 4.44
14 21 1.31 16.25 12 1.12 18.75 14.14 13.25 15.75 14 2.19 4.94
16 23.5 1.38 18.5 16 1.12 21.25 16.16 15.25 18 16 2.44 4.94
18 25 1.5 21 16 1.25 22.75 18.18 17.25 19.88 18 2.62 5.44
20 27.5 1.62 23 20 1.25 25 20.2 19.25 22 20 2.81 5.62
22 29.5 1.75 25.25 20 1.38 27.25 22.22 21.25 24.25 22 3.07 5.82
24 32 1.81 27.25 20 1.38 29.5 24.25 23.25 26.12 24 3.19 5.94


  • Dimensions are in inches.
  • Bolt hole diameter 1/8″ larger than bolt diameter.
  • Dimensions are in inches.
  • Bolt hole diameter 1/8″ larger than bolt diameter.

ANSI/ASME B16.5 Class 400 Forged Flanges   20221129002839 83057 - ANSI/ASME B16.5 Flanges

* WN Bore ID (WB): To be specified by purchaser

Nominal Size Outside Diameter Min. Thickness RF Dia. No. of Bolt Holes Diameter of Holes Bolt Circle SO Bore ID Dia. Hub Base Dia. Hub Top SO LTH WN LTH * WN Bore ID
(OD) (T) (R) (BC) (SB) (HB) (HT) (SL) (WL) (WB)
12 3.75 0.56 1.38 4 0.63 2.62 0.88 1.5 0.84 0.88 2.06 *
34 4.62 0.62 1.69 4 0.75 3.25 1.09 1.88 1.05 1 2.25 *
1 4.88 0.69 2 4 0.75 3.5 1.36 2.12 1.32 1.06 2.44 *
114 5.25 0.81 2.5 4 0.75 3.88 1.7 2.5 1.66 1.12 2.62 *
112 6.12 0.88 2.88 4 0.88 4.5 1.95 2.75 1.9 1.25 2.75 *
2 6.5 1 3.62 8 0.75 5 2.44 3.31 2.38 1.44 2.88 *
212 7.5 1.12 4.12 8 0.88 5.88 2.94 3.94 2.88 1.62 3.12 *
3 8.25 1.25 5 8 0.88 6.62 3.57 4.62 3.5 1.81 3.25 *
312 9 1.38 5.5 8 1 7.25 4.07 5.25 4 1.94 3.38 *
4 10 1.38 6.19 8 1 7.88 4.57 5.75 4.5 2 3.5 *
5 11 1.5 7.31 8 1 9.25 5.66 7 5.56 2.12 4 *
6 12.5 1.62 8.5 12 1 10.62 6.72 8.12 6.63 2.25 4.06 *
8 15 1.88 10.62 12 1.12 13 8.72 10.25 8.63 2.69 4.62 *
10 17.5 2.12 12.75 16 1.25 15.25 10.88 12.62 10.75 2.88 4.88 *
12 20.5 2.25 15 16 1.38 17.75 12.88 14.75 12.75 3.12 5.38 *
14 23 2.38 16.25 20 1.38 20.25 14.14 16.75 14 3.31 5.88 *
16 25.5 2.5 18.5 20 1.5 22.5 16.16 19 16 3.69 6 *
18 28 2.62 21 24 1.5 24.75 18.18 21 18 3.88 6.5 *
20 30.5 2.75 23.12 24 1.62 27 20.2 23.12 20 4 6.62 *
22 33 2.88 25.25 24 1.75 29.25 22.22 25.25 22 4.25 6.75 *
24 36 3 27.25 24 1.88 32 24.25 27.62 24 4.5 6.88 *


  • Dimensions are in inches.
  • Bolt hole diameter 1/8″ larger than bolt diameter.

ANSI/ASME B16.5 Class 600 Forged Flanges 20221129002839 83057 - ANSI/ASME B16.5 Flanges

* WN Bore ID (WB): To be specified by purchaser

Nominal Size Outside Diameter Min. Thickness RF Dia. No. of Bolt Holes Diameter of Holes Bolt Circle SO Bore ID Dia. Hub Base Dia. Hub Top SO LTH WN LTH * WN Bore ID
(OD) (T) (R) (BC) (SB) (HB) (HT) (SL) (WL) (WB)
12 3.75 0.56 1.38 4 0.63 2.62 0.88 1.5 0.84 0.88 2.06 *
34 4.62 0.62 1.69 4 0.75 3.25 1.09 1.88 1.05 1 2.25 *
1 4.88 0.69 2 4 0.75 3.5 1.36 2.12 1.32 1.06 2.44 *
114 5.25 0.81 2.5 4 0.75 3.88 1.7 2.5 1.66 1.12 2.62 *
112 6.12 0.88 2.88 4 0.88 4.5 1.95 2.75 1.9 1.25 2.75 *
2 6.5 1 3.62 8 0.75 5 2.44 3.31 2.38 1.44 2.88 *
212 7.5 1.12 4.12 8 0.88 5.88 2.94 3.94 2.88 1.62 3.12 *
3 8.25 1.25 5 8 0.88 6.62 3.57 4.62 3.5 1.81 3.25 *
312 9 1.38 5.5 8 1 7.25 4.07 5.25 4 1.94 3.38 *
4 10.75 1.5 6.19 8 1 8.5 4.57 6 4.5 2.12 4 *
5 13 1.75 7.31 8 1.12 10.5 5.66 7.44 5.56 2.38 4.5 *
6 14 1.88 8.5 12 1.12 11.5 6.72 8.75 6.63 2.62 4.62 *
8 16.5 2.19 10.62 12 1.25 13.75 8.72 10.75 8.63 3 5.25 *
10 20 2.5 12.75 16 1.38 17 10.88 13.5 10.75 3.38 6 *
12 22 2.62 15 20 1.38 19.25 12.88 15.75 12.75 3.62 6.12 *
14 23.75 2.75 16.25 20 1.5 20.75 14.14 17 14 3.69 6.5 *
16 27 3 18.5 20 1.63 23.75 16.16 19.5 16 4.19 7 *
18 29.25 3.25 21 20 1.75 25.75 18.18 21.5 18 4.62 7.25 *
20 32 3.5 23 24 1.75 28.5 20.2 24 20 5 7.5 *
22 34.25 3.75 25.25 24 1.88 30.63 22.22 26.25 22 5.25 7.75 *
24 37 4 27.25 24 2 33 24.25 28.25 24 5.5 8 *


  • Dimensions are in inches.
  • Bolt hole diameter 1/8″ larger than bolt diameter.

ANSI/ASME B16.5 Class 900 Forged Flanges 20221129002839 83057 - ANSI/ASME B16.5 Flanges

* WN Bore ID (WB): To be specified by purchaser

Nominal Size Outside Diameter Min. Thickness RF Dia. No. of Bolt Holes Diameter of Holes Bolt Circle SO Bore ID * WN Bore ID Dia. Hub Base Dia. Hub Top SO LTH WN LTH
(OD) (T) (R) (BC) (SB) (WB) (HB) (HT) (SL) (WL)
3 9.5 1.5 5 8 1 7.5 3.57 * 5 3.5 2.12 4
4 11.5 1.75 6.19 8 1.25 9.25 4.57 * 6.25 4.5 2.75 4.5
5 13.75 2 7.31 8 1.38 11 5.66 * 7.5 5.56 3.12 5
6 15 2.19 8.5 12 1.25 12.5 6.72 * 9.25 6.63 3.38 5.5
8 18.5 2.5 10.63 12 1.5 15.5 8.72 * 11.75 8.63 4 6.38
10 21.5 2.75 12.75 16 1.5 18.5 10.88 * 14.5 10.75 4.25 7.25
12 24 3.12 15 20 1.5 21 12.88 * 16.5 12.75 4.63 7.88
14 25.25 3.38 16.25 20 1.63 22 14.14 * 17.75 14 5.12 8.38
16 27.75 3.5 18.5 20 1.75 24.25 16.16 * 20 16 5.25 8.5
18 31 4 21 20 2 27 18.18 * 22.25 18 6 9
20 33.75 4.25 23 20 2.13 29.5 20.2 * 24.5 20 6.25 9.75
24 41 5.5 27.25 20 2.63 35.5 24.25 * 29.5 24 8 11.5


  • Dimensions are in inches.
  • Bolt hole diameter 1/8″ larger than bolt diameter.

ANSI/ASME B16.5 Class 1500 Forged Flanges 20221129002839 83057 - ANSI/ASME B16.5 Flanges

* WN Bore ID (WB): To be specified by purchaser

Nominal Size Outside Diameter Min. Thickness RF Dia. No. of Bolt Holes Diameter of Holes Bolt Circle So Bore ID Dia. Hub Base Dia. Hub Top SO LTH WN LTH * WN Bore ID
(OD) (T) (R) (BC) (SB) (HB) (HT) (SL) (WL) (WB)
12 4.75 0.88 1.38 4 0.88 3.25 0.88 1.5 0.84 1.25 2.38 *
34 5.12 1 1.69 4 0.88 3.5 1.09 1.75 1.05 1.38 2.75 *
1 5.88 1.12 2 4 1 4 1.36 2.06 1.32 1.62 2.88 *
114 6.25 1.12 2.5 4 1 4.38 1.7 2.5 1.66 1.62 2.88 *
112 7 1.25 2.88 4 1.12 4.88 1.95 2.75 1.9 1.75 3.25 *
2 8.5 1.5 3.63 8 1 6.5 2.44 4.12 2.38 2.25 4 *
212 9.62 1.62 4.13 8 1.12 7.5 2.94 4.88 2.88 2.5 4.12 *
3 10.5 1.88 5 8 1.25 8 5.25 3.5 4.62 *
4 12.25 2.12 6.19 8 1.38 9.5 6.38 4.5 4.88 *
5 14.75 2.88 7.31 8 1.63 11.5 7.75 5.56 6.12 *
6 15.5 3.25 8.5 12 1.5 12.5 9 6.63 6.75 *
8 19 3.62 10.63 12 1.75 15.5 11.5 8.63 8.38 *
10 23 4.25 12.75 12 2 19 14.5 10.75 10 *
12 26.5 4.88 15 16 2.12 22.5 17.75 12.75 11.12 *
14 29.5 5.25 16.25 16 2.38 25 19.5 14 11.75 *
16 32.5 5.75 18.5 16 2.63 27.75 21.75 16 12.25 *
18 36 6.38 21 16 2.88 30.5 23.5 18 12.88 *
20 38.75 7 23 16 3.12 32.75 25.25 20 14 *
24 46 8 27.25 16 3.63 39 30 24 16 *


  • Dimensions are in inches.
  • Bolt hole diameter 1/8″ larger than bolt diameter.

ANSI/ASME B16.5 Class 2500 Forged Flanges 20221129002839 83057 - ANSI/ASME B16.5 Flanges

* WN Bore ID (WB): To be specified by purchaser

Nominal Size Outside Diameter Min. Thickness RF Dia. No. of Bolt Holes Diameter of Holes Bolt Circle Dia. Hub Base Dia. Hub Top SO LTH WN LTH * WN Bore ID
(OD) (T) (R) (BC) (HB) (HT) (SL) (WL) (WB)
12 5.25 1.19 1.38 4 0.88 3.5 1.69 0.84 1.56 2.88 *
34 5.5 1.25 1.69 4 0.88 3.75 2 1.05 1.69 3.12 *
1 6.25 1.38 2 4 1 4.25 2.25 1.32 1.88 3.5 *
114 7.25 1.5 2.5 4 1.12 5.13 2.88 1.66 2.06 3.75 *
112 8 1.75 2.88 4 1.25 5.75 3.12 1.9 2.38 4.38 *
2 9.25 2 3.63 8 1.12 6.75 3.75 2.38 2.75 5 *
212 10.5 2.25 4.13 8 1.25 7.75 4.5 2.88 3.12 5.62 *
3 12 2.62 5 8 1.38 9 5.25 3.5 6.62 *
4 14 3 6.19 8 1.63 10.75 6.5 4.5 7.5 *
5 16.5 3.62 7.31 8 1.88 12.75 8 5.56 9 *
6 19 4.25 8.5 8 2.12 14.5 9.25 6.63 10.75 *
8 21.75 5 10.63 12 2.12 17.25 12 8.63 12.5 *
10 26.5 6.5 12.75 12 2.63 21.25 14.75 10.75 16.5 *
12 30 7.25 15 12 2.88 24.38 17.38 12.75 18.25 *


  • Dimensions are in inches.
  • Bolt hole diameter 1/8″ larger than bolt diameter.

ANSI B 16.1 CLASS 125 Slip On Flanges 20221129015109 85860 - ANSI/ASME B16.5 Flanges

Nominal Size Outside Diameter Thickness Diameter at Base Bore LTH Drilling – Bolt Circle Drilling – Hole Diameter Drilling – No. of Holes Weight
(OD) (T) (E) (B) (L) (BC) (lbs)
26 34.25 2 28.5 26.19 3.375 31.75 1.375 24 235
28 36.5 2.062 30.75 28.19 3.438 34 1.375 28 269
30 38.75 2.125 32.75 30.19 3.5 36 1.375 28 303
32 41.75 2.25 35 32.19 3.625 38.5 1.625 28 375
34 43.75 2.312 37 34.19 3.688 40.5 1.625 32 401
36 46 2.375 39.25 36.19 3.75 42.75 1.625 32 452
38 48.75 2.375 41.75 38.19 3.75 45.25 1.625 32 528
40 50.75 2.5 43.75 40.19 3.875 47.25 1.625 36 573
42 53 2.625 46 42.19 4 49.5 1.625 36 648
44 55.25 2.625 48 44.19 4 51.75 1.625 40 688
46 57.25 2.688 50 46.19 4.062 53.75 1.625 40 733
48 59.5 2.75 52.25 48.19 4.125 56 1.625 44 799
50 61.75 2.75 54.25 50.19 4.125 58.25 1.875 44 827
52 64 2.875 56.5 52.19 4.25 60.5 1.875 44 922
54 66.25 3 58.75 54.19 4.375 62.75 1.875 44 1024
60 73 3.125 65.25 60.19 4.5 69.25 1.875 52 1253
66 80 3.375 71.5 66.19 4.875 76 1.875 52 1623
72 86.5 3.5 78.5 72.19 5 82.5 1.875 60 1922
78 93 3.875 84.5 78.19 5.375 89 2.125 64 2279
84 99.75 3.875 90.5 84.19 5.375 95.5 2.125 64 2586
90 106.5 4.25 96.75 90.19 5.75 102 2.438 68 3061
96 113.25 4.25 102.75 96.19 5.75 108.5 2.438 68 3432


  • Dimensions are in inches.
  • ANSI B16.1 is a gray iron pipe flange and fitting specification.
  • Steel flanges are occasionally produced to mate up with Class 125 and Class 250 valves
  • These flange dimensions are provided for reference even though specification does not cover steel.
  • These flanges are typically supplied with a flat face.

ANSI B 16.1 CLASS 125 Weldneck Flanges   20221129015351 60270 - ANSI/ASME B16.5 Flanges

* Bore (B2): To be specified by purchaser

Nominal Size Outside Diameter Thickness Raised Face Dia. Diameter At Base * Bore Diameter Bevel LTH Drilling – Bolt Circle Drilling – Hole Diameter Drilling – No. of Holes Weight
(OD) (T) (R) (X) (B2) (H) (L2) (BC) (lbs)
26 34.25 2 29.5 28.5 * 26 5 31.75 1.38 24 265
28 36.5 2.06 31.5 30.75 * 28 5.06 34 1.38 28 295
30 38.75 2.13 33.75 32.75 * 30 5.13 36 1.38 28 340
32 41.75 2.25 36 35 * 32 5.25 38.5 1.63 28 410
34 43.75 2.31 38 37 * 34 5.31 40.5 1.63 32 440
36 46 2.38 40.25 39.25 * 36 5.38 42.75 1.63 32 495
38 48.75 2.38 42.25 41.75 * 38 5.38 45.25 1.63 32 570
40 50.75 2.5 44.25 43.75 * 40 5.5 47.25 1.63 36 620
42 53 2.63 47 46 * 42 5.63 49.5 1.63 36 710
44 55.25 2.63 49 48 * 44 5.63 51.75 1.63 40 750
46 57.25 2.69 51 50 * 46 5.68 53.75 1.63 40 800
48 59.5 2.75 53.5 52.25 * 48 5.75 56 1.63 44 870
50 61.75 2.75 55.5 54.25 * 50 5.75 58.25 1.88 44 900
52 64 2.88 57.5 56.5 * 52 5.88 60.5 1.88 44 1000
54 66.25 3 59.75 58.75 * 54 6 62.75 1.88 44 1100
60 73 3.13 66 65.25 * 60 6.13 69.25 1.88 52 1350
66 80 3.38 71.5 * 66 6.38 76 1.88 52 1775
72 86.5 3.5 78.5 * 72 6.5 82.5 1.88 60 2100
84 99.75 3.88 90.5 * 84 6.88 95.5 2.13 64 2825
96 113.25 4.25 102.75 * 96 7.25 108.5 2.44 68 3800


  • Dimensions are in inches.
  • ANSI B16.1 is a gray iron pipe flange and fitting specification.
  • Steel flanges are occasionally produced to mate up with Class 125 and Class 250 valves
  • These flange dimensions are provided for reference even though specification does not cover steel.
  • These flanges are typically supplied with a flat face.

ANSI B16.1 Class 250 Flanges  

20221129020007 95909 - ANSI/ASME B16.5 Flanges

* Bore – WN (B2): To be specified by purchaser

Nominal Size Outside Diameter Thickness Raised Face Dia. Diameter at Base Bore – SO LTH – Weld Neck LTH – SO Drilling – Bolt Circle Drilling – Hole Diameter Drilling – No. of Holes Weight – Weld Neck Weight – Slip-on Weight – Blind * Bore – WN
(OD) (T) (R) (X) (B) (L2) (L) (BC) (lbs) (lbs) (lbs) (B2)
26 38.25 2.81 32.44 30.5 26.25 5.81 4.75 34.5 1.88 28 534 531 916 *
28 40.75 2.94 34.94 33 28.25 5.94 5 37 1.88 28 629 637 1095 *
30 43 3 37.19 35.25 30.25 6 5 39.25 1.88 28 702 707 1236 *
32 45.25 3.12 39.44 37.5 32.25 6.12 5.12 41.5 1.88 28 793 801 1424 *
34 47.5 3.25 41.44 39.5 34.25 6.25 5.25 43.5 1.88 28 882 889 1649 *
36 50 3.38 43.69 41.5 36.25 6.38 5.38 46 2.13 32 969 970 1884 *
38 52.25 3.44 45.69 43.5 38.25 6.44 5.5 48 2.13 32 1057 1062 2094 *
40 54.25 3.56 47.94 45.75 40.25 6.56 5.5 50.25 2.13 36 1158 1172 2336 *
42 57 3.69 50.44 47.75 42.25 6.94 5.62 52.75 2.125 36 1318 1288 2673 *
44 59.25 3.75 52.69 49.75 44.25 7 5.75 55 2.13 36 1423 1397 2935 *
46 61.5 3.88 54.94 51.75 46.25 7.12 5.88 57.25 2.13 40 1536 1510 3272 *
48 65 4 58.44 54 48.25 7.25 6 60.75 2.13 40 1824 1797 3768 *


  • Dimensions are in inches.
  • ANSI B16.1 is a gray iron pipe flange and fitting specification.
  • Steel flanges are occasionally produced to mate up with Class 125 and Class 250 valves.
  • These flange dimensions are provided for reference even though specification does not cover steel.
  • These flanges are typically supplied with a flat face.
  • The flanges are typically supplied with a flat face.

Forged Steel 150# Lap-Joint Flanges

Slip On Length through Hub

20221129020508 59817 - ANSI/ASME B16.5 Flanges

Nominal Size Outside Diameter Bore Diameter No. of Bolt Holes Diameter Of Holes Bolt Circle Thickness Hub Length Hub Diameter Lap Radus Weight Each
(OD) (B) (BC) (T) (L) (H) (lbs)
1 4.25 1.38 4 0.625 3.13 0.563 0.688 1.938 0.13 2
114 4.63 1.72 4 0.625 3.5 0.625 0.813 2.312 0.19 3
112 5 1.97 4 0.625 3.88 0.688 0.875 2.563 0.25 3
2 6 2.46 4 0.75 4.75 0.75 1 3.063 0.31 5
212 7 2.97 4 0.75 5.5 0.875 1.125 3.563 0.31 7
3 7.5 3.6 4 0.75 6 0.938 1.188 4.25 0.38 8
312 8.5 4.1 8 0.75 7 0.938 1.25 4.812 0.38 11
4 9 4.6 8 0.75 7.5 0.938 1.312 5.312 0.44 13
5 10 5.69 8 0.875 8.5 0.938 1.438 6.438 0.44 15
6 11 6.75 8 0.875 9.5 1 1.562 7.562 0.5 18
8 13.5 8.75 8 0.875 11.75 1.125 1.75 9.688 0.5 30
10 16 10.92 12 1 14.25 1.188 1.938 12 0.5 42
12 19 12.92 12 1 17 1.25 2.188 14.375 0.5 64
14 21 14.19 12 1.125 18.75 1.375 2.25 15.75 0.5 90
16 23.5 16.19 16 1.125 21.25 1.438 2.5 18 0.5 98
18 25 18.2 16 1.25 22.75 1.562 2.688 19.875 0.5 125
20 27.5 20.25 20 1.25 25 1.688 2.875 22 0.5 160
24 32 24.25 20 1.375 29.5 1.875 3.25 26.125 0.5 212
30** 38.75 30.25 28 1.375 36 2.125 3.5 32.75 0.5 305
36** 46 36.25 32 1.625 42.75 2.375 3.75 39.25 0.5 440


  • ANSI B16.5 150# SO Drill Pattern.
  • Bore Diameters listed above are stocked by CAB as standard. Larger or special bores are available on application. Hub lengths shown for 14″ – 24″ sizes are standard 150# S/O dimension. They do not conform to full ANSI B16.5 Hub Length dimensions which are available on application.
  • Bores are finished with a lap joint radius.
  • ** 30/36″ sizes listed are Class 125 (Full Weight) S/O pattern with Lap-Joint ID. Sizes larger than 24″ are not covered by ANSI B16.5.

Manufacturing processes of flanges

Flange production process mainly includes forging, casting, cutting and rolling: Casting is a method of casting liquid metal into a casting cavity which is suitable for the shape of the flange. After it is cooled and solidified, the blank of the flange can be obtained most of the cast materials are originally solid but heated to liquid metal (e.g. copper, iron, aluminum, tin, stainless steel, etc.), while the mold materials can be sand, metal or even ceramics. Forged flange is one of the products with the best mechanical properties in flange products. Its raw material is generally tube blank, and then it is cut and hammered continuously to eliminate segregation, looseness and other defects in ingot. The price and mechanical properties are one grade higher than the common cast flange. Flange is the part that connects the pipe with the pipe and the valve, and is connected to the pipe end; it is also useful for the flange on the inlet and outlet of the equipment, and is used for the connection between the two equipment, which is the part that connects the pipe with the pipe, and is connected to the pipe end. It is a kind of accessory product of pipeline. The main materials of forged flange are carbon steel, alloy steel and stainless steel. The main standards are national standard, electric standard, American Standard, German standard, Japanese standard, etc. The main anti-corrosion treatment includes oiling and galvanizing. Forged flange has good pressure and temperature resistance, which is generally suitable for high pressure and high temperature working environment. The inner and outer diameter and thickness of the flange are directly cut out on the steel plate, and then the bolt hole and water line are processed. The flange produced in this way is called cut flange. The maximum diameter of such flange is limited to the width of steel plate. The rolling flange is made by cutting the middle plate into battens, then rolling it into circular welded joints, and then flattening it. Coiling can be divided into cold coiling and hot coiling. After machining into a circle, the water line, bolt hole, stop and other processes shall be processed. This is generally a large flange, one-time molding can be up to 7 meters. Plate type flat welding flange is the most common, and the connection mode is welding. If the production process of segmented production is used, the specification of 12m-15m or larger can be achieved. This kind of flange has good quality assurance. Because the raw material is medium plate with good density. The welding process at the joint of the rolling flange is the most important, and X-ray or ultrasonic film detection shall be carried out. If the joint is finished, there will be no problem with the material of the whole flange. Relatively speaking, the price of the products with thin thickness, light weight, narrow one side of the products, and some processing with sealing grooves is higher, while the price of some rolling flanges with thick, heavy weight and without very complicated processing technology is lower. When processing bolt holes, it is not allowed to drill the bolt holes to the places with welded joints. This kind of flange is made of carbon steel, stainless steel, alloy steel, etc.

Production process of cast flange and forged flange

Production process of casting flange:

  • ① Put the selected raw material steel into medium frequency electric furnace for smelting, so that the temperature of molten steel can reach 1600-1700 ℃;
  • ② Preheat the metal mould to 800-900 ℃ and keep constant temperature;
  • ③ Start the centrifuge, inject the steel water in step ① into the metal mold after preheating in step;
  • ④ The casting is naturally cooled to 800-900 ℃ and kept for 1-10 minutes;
  • ⑤ Cool with water to near normal temperature, demould and take out the casting.

Let’s learn about the production process of forged flange:

The forging process is generally composed of the following processes: blanking, heating, forming and cooling after forging. The forging process includes free forging, die forging and die forging. In production, different forging methods are selected according to the forging quality and production batch.

1574892549393073 - ANSI/ASME B16.5 Flanges Free forging has low productivity and large machining allowance, but the tool is simple and versatile, so it is widely used to forge single piece and small batch forgings with simple shape. The free forging equipment includes air hammer, steam air hammer and hydraulic press, which are suitable for the production of small, medium and large forgings respectively. Die forging has the advantages of high productivity, simple operation, mechanization and automation. Die forgings have high dimensional accuracy, small machining allowance and more reasonable fiber structure distribution, which can further improve the service life of parts. Basic process of free forging: during free forging, the shape of forgings is gradually forged into blanks through some basic deformation processes. The basic process of free forging includes upsetting, drawing, punching, bending and cutting.

  • 1. Upsetting and upsetting is the process of forging the original billet along the axial direction to reduce its height and increase its cross section. This process is often used to forge gear blanks and other disc forgings. Upsetting can be divided into full upsetting and partial upsetting.
  • 2. Drawing length is a forging process that increases the length of the blank and reduces the cross-section. It is usually used to produce shaft parts, such as lathe spindle, connecting rod, etc.
  • 3. Forging process of punching through hole or through hole on blank with punch.
  • 4. Forging process of bending the blank to a certain angle or shape.
  • 5. The forging process in which one part of the billet rotates at an angle to the other.
  • 6. Forging process of cutting split blank or cutting head.

Die forging

Die forging is called model forging. The heated blank is placed in the forging die fixed on the die forging equipment for forging.

  • 1. Basic process of die forging process: blanking, heating, pre forging, final forging, punching and connecting skin, trimming, tempering and shot peening. Common processes include upsetting, drawing, bending, punching and forming.
  • 2. Common die forging equipment: die forging hammer, hot die forging press, flat forging machine, friction press, etc.

Generally speaking, the quality of forged flange is better. Generally, it is produced by die forging, with fine crystal structure, high strength and high price.

  • Both cast flange and forged flange are common manufacturing methods of flange. According to the strength requirements of components to be used, if the requirements are not high, turning flange can also be selected.
  • The shape and size of the casting blank are accurate, the machining amount is small and the cost is low, but there are casting defects (porosity, crack and inclusion); the internal structure streamline of the casting is poor (if it is a cutting part, the streamline is worse);
  • Forged flange is generally lower carbon content than cast flange and is not easy to rust. The forging has good streamline, compact structure and better mechanical properties than cast flange;
  • If the forging process is not proper, there will be large or uneven grains, hardening cracks, and the forging cost is higher than that of casting flange.
  • Forgings can bear higher shear force and tensile force than castings.
  • The advantages of casting are that it can produce more complex shape and lower cost;
  • The forging has the advantages of uniform internal structure and no harmful defects such as pores and inclusions in the casting;
  • The density of forged flange is higher than that of cast flange. That is to say, the quality of forging is better than that of casting.

Cutting flange

1574892593466806 - ANSI/ASME B16.5 Flanges

The inner and outer diameter and thickness of the flange are directly cut out on the middle plate, and then the bolt hole and water line are processed. The flange produced in this way is called cut flange. The maximum diameter of such flange is limited to the width of the middle plate.

Rolled flange

The process of using the middle plate to cut the sliver and then roll it into a circle is called rolling, which is mostly used in the production of some large flanges. After coiling, welding, flattening and processing of waterline and bolt hole are carried out.

How to distinguish the advantages and disadvantages of forged flange?

Flange forging is a common method. As a common processing method, forging plays a very important role in our industrial production. Many people don’t know it very well, but forging products in our life are very common. Ring forging is widely used in people’s life. It is very important to distinguish the forging flange’s merits and demerits. Next, I will introduce the judgment method to you Experienced people can judge the quality and performance of forged flange only by observing it. For the observation of forged flange, generally speaking, if the first feeling of a forged flange product is that the surface of the product is very smooth, then such a product can basically be judged as a relatively qualified product In addition, in addition to feeling, it is also important to observe the bolts of forged flange. This is mainly to see the chamfering of the bolt and the position of the bolt hole from the flange edge. The quality of bolt chamfer is directly related to the responsibility of forging flange manufacturer. The location of the bolt hole from the edge of the forged flange also has certain attention. If the forging flange is relatively close, its forged flange products must be non-standard. For professional forging flange manufacturers, the product quality and reputation is very important for the enterprise, so for the better development of the enterprise, the quality and safety of forging flange will be strictly controlled. In fact, it is not difficult to distinguish the quality of forged flange. As long as you master the correct methods and learn some experience skills, you can easily identify and find forged flange products with good quality, excellent performance and low price.

Inspection Quality of ANSI/ASME B16.5 Flanges

The inspection quality of ANSI/ASME B16.5 flanges is done by the manufacturer. The inspector checks that the flange meets all requirements and conforms to standards, including tolerances and materials. Inspectors check:

  • Measuring dimensions.
  • Checking bolt holes are not too large or too small for bolts to fit in them securely.
  • Numbering matching products together so they can be assembled without confusion by other workers on projects where more than one type of fitting is used.

Package of ANSI/ASME B16.5 Flanges

We can package the ANSI/ASME B16.5 flanges according to customers’ requirements, such as the packing of a pair of flange in one box, or packaging each flange in separate boxes. In addition, we can supply the ANSI/ASME B16.5 flanges in bulk or in small quantities according to customers’ needs.

Transportation of flange

It is important to transport flange in a safe manner so that it does not get damaged. The best way to store pipe flanges is in their original packaging and place them in a sturdy container, such as a plastic crate or wooden box. If you do not have the original packaging, then make sure that the flange is well wrapped with bubble wrap or foam sheets before storing it. Never store any steel materials or pipes without covering them with protective covers such as shrink wrapping or stretch wrappers because moisture can damage them easily. You should also take care to avoid any sharp objects touching your material while it’s being transported; try putting some padding between the object and other materials like wood panels if necessary.

Application of ANSI/ASME B16.5 Flanges

ASME B16.5 ASME B16.5 Flanges are known to deliver exceptional performance and are generally developed for meeting the demands. We oer a broad range of ASME B16.5 Flanges through a worldwide network of stockkeeping branches. These ASME B16.5 Flange is use in various industries like:

  • Stainless Steel ASME B16.5 Flanges uses in Oil and Gas Pipeline;
  • ASME B16.5 Flanges uses in Chemical Industry;
  • Alloy Steel ASME B16.5 Flanges uses in Plumbing;
  • ASME B16.5 Flanges uses in Heating;
  • ASME B16.5 Pipe Flanges uses in Water Supply Systems;
  • ANSI B16.5 Flanges uses in Power Plant;
  • ASME B16.5 Flanges uses in Paper & Pulp Industry;
  • ASME B16.5 Flange uses in General Purpose Applications;
  • Steel ASME B16.5 Flanges uses in Fabrication Industry;
  • ASME B16.5 Flange uses in Food Processing Industry;
  • ASME B16.5 Flanges uses in Structural Pipe.

Price of flange

Price of flange is also determined by the material used to make it. Flanges can be made of different materials, and each material has its own cost. For example, steel is cheaper than stainless steel. Another factor that affects the price of a flange is the size of the flange. Large-sized flanges are more expensive than small-sized ones as labor costs associated with producing big equipment are higher compared to small equipment. Also, large-sized equipment usually require high quality raw materials for manufacturing which drives up their production costs as well as final prices offered by suppliers or manufacturers alike.

Flange installation

To install the flange, you’ll need to first measure and cut the pipe to length. Next, slip a gasket onto each end of the pipe. Apply pipe dope (a special solvent) to both sides of the gasket and place it in between two pieces of pipe; this will form a watertight seal when pressed together with a wrench. Once your pipes are cut and gaskets are in place, slide on your flange and tighten with either a torque wrench or by hand—it’s best not to over-tighten them. Finally, apply grease or oil inside each hole before installing bolts through them as well as nuts onto threaded ends outside holes.

Flange maintenance

While maintaining your pipe flange is not difficult, it’s important to keep them clean and free from dirt, paint, oil/grease or other coatings that may have been applied to the flanges. Rust and corrosion can also accumulate on pipe flanges over time. This can weaken the seal while also preventing you from properly installing your new pipes. In addition to cleaning off rust and corrosion, check for any cracks or damage that may prevent you from completing your project as planned.

Marking of flange

The marking of flange is one of the important things that should be considered while buying a pipe flange. The marking includes manufacturer’s name, designation, rating, pressure rating and material. The size of the pipe flange is also given in it along with type of flange.

How to purchase the correct ANSI/ASME B16.5 flanges

Flanges are typically made of metal materials and have a series of holes around them that allow you to easily connect pipes together with bolts and nuts, while ensuring they stay tight over time. There are many different types of flanges available on the market today, but most manufacturers provide similar designs so choosing one isn’t difficult at all! You just need some basic knowledge about how flanges work before heading out into the world looking for one:

1. Know the application

Knowing the application is key to selecting the correct flange. The type and grade of material, the diameter, the facing and pressure rating are all important factors in determining which flange will be best for your needs. In addition to these specifications, you must also consider whether an ASME stamp is required or if a Class 150 or Class 600 flange will do for your application.

2. Select a flange facing

Facing types are the part of a flange that sits against the pipe and allows for easy installation. You can choose from welded, bolted or threaded facings for your project. Welded facings are the most common type and work best in situations where you need to seal up pipes quickly or under heavy pressure. They’re also ideal when you want to avoid having to install extra hardware like bolts or screws. If welding isn’t an option for you (due to budget constraints, time constraints or lack of expertise), threaded facings may be a good alternative since they are easier to install than either welded or bolted facings but still offer some benefits over them by allowing you more control over how tightly they fit together without risk of stripping threads during installation process.

3. Choose the material of the flange

Choosing the material of a flange is an important part of its design. The thickness, diameter and material type chosen will depend on the pressure, temperature and chemical environment that your flange will be exposed to. You will want to determine the flange material for your system. The following are the most common pipe flange materials:

  • Cast iron. This inexpensive material is durable and readily available, but it can corrode in areas with high moisture or salt content.
  • Stainless steel (SS). This corrosion-resistant metal is strong and durable, but more expensive than cast iron or malleable iron.
  • Malleable iron (MI). A versatile choice because it’s easy to work with and has similar properties to stainless steel at a lower cost than SS.

For example, if you are working with extremely corrosive materials in your application, it would be wise to consider using a stainless steel ASME B16.5 t-flange or an alloy steel A105 bolt-on t-flange. Both have very high corrosion resistance properties which make them ideal in these situations. When you’re looking at buying a flange, there are several factors you should consider:

  • If a high temperature application exists, consider using an Incoloy Grade 800H/HT alloy instead of Inconel 600 alloy when working in temperatures above 1,000 degrees Fahrenheit (537 Celsius). This will allow better welding, better corrosion resistance and longer lifespan than Inconel 600 alloy and stainless steel grades combined.
  • Incoloy 800 is an age-hardening nickel-alloy with good strength at elevated temperatures. It has excellent resistance to chloride stress corrosion cracking due to the formation of eutectic chlorides with low solubility in water and other common fluids. It can be used as an alternative to Hastelloy X in conditions where these properties are required but thermal cycling may cause problems with Hastelloy X (eutectic precipitation can occur after 1 million cycles).

However, if you are working with oil or other fluids that are not overly aggressive but may still damage certain materials over time then perhaps choosing an alloy steel A182 bolt-on buttwelding tee flange could be more effective because it is less expensive than other options yet still offers good long term durability when compared to other alloys such as carbon steel grades 1 through 10XX series alloys which also offer good corrosion resistance properties but are much less resistant than those previously mentioned (especially during initial exposure).

4. Choose the pressure rating of the flange

The pressure rating of a flange is determined by the thickness of the flange and the material it is made from. Lower pressure ratings are used for low pressure applications, while higher pressure ratings are used for high pressure applications. In this example, we will choose to use ANSI Class 150 RF flanges with a maximum allowable working pressure (MAWP) of 150 pounds per square inch (psi). Because our application requires a thinner walled flange (3/8 inch), we will need to select an ANSI Class 150 LF flange instead to meet our MAWP requirements.

5. Choose the type of flange required

Choosing the right kind of flange for your piping system is an important part of designing it correctly. There are many different types of flanges, and each has its own pros and cons depending on the application. The most common types include:

  • Buttweld – Buttweld fittings are made by joining two pieces of pipe together with a welded seam at the end.
  • Socketweld – Socketweld fittings are made by inserting a sleeve into one end of a pipe and then welding this sleeve to another piece of pipe that has been inserted into it from the other end; no weld seams are visible in these types of flanges because only one side needs to be welded in order for them to work properly (this process can also be done with buttweld fittings).
  • Blind Flanges – Blind Flanges are also known as slip-on or press fit flanges because they require no screwing or bolting down prior installation; instead, they lock themselves into place once installed through friction alone thanks largely due their design which includes grooves cut around them so they sit flush against whatever surface they’re meant attaching themselves too without having any gaps between pipes where leaks could occur later down line when pressure builds up inside those areas.”

6. Choose the standard to which the flange conforms

As you may already know, the standard to which your flange conforms is a critical determinant of its quality. If a flange does not meet the standards set by ASME B16.5 and ANSI, it cannot be accepted for use in any project or industrial process. This section will walk you through everything you need to know about choosing the correct standard for your application. The first step is determining whether your product falls under either type of ANSI/ASME B16.5 flange: Class 150 or 300 series (i.e., 150# NB 1010-06N or 300# NB 2040-08N). This can be done by reading its product name and checking if there are any special designations listed that indicate which type of material was used in its manufacturing process (for example: “150# NB 1010-06N”).

7. Choose the size of the flange

The diameter and thickness are two important factors to consider when ordering a B16.5 flange. The sizing of a flange is also determined by its application and the material that it will be subjected too. If you have any questions about your particular application, please contact us so we can help you choose the right size for your needs. Flanges are manufactured in standard sizes ranging from 2” to 20” with most common sizes being 6″, 8″, 10″, 12″, 14″ 16″ and 20″. The nominal size is determined by adding the diameter plus twice the wall thickness (or schedule). For example, an 8-inch NPSM flange has an inside diameter (ID) of 7 inches plus twice its wall thickness which equals 9 inches total ID measurement or nominal size plus twice its thickness which = 11 inch total ID measurement or nominal size.

8. Choose whether or not any special features are required on the flange, e.g. machining, testing or inspection requirements, or whether you want it to be coated in some way.

These options can include:

  • Machining – this includes cutting holes in the flange; drilling holes through both ends of the flange; slotting one end of the pipe and flange (for expansion joints); and milling slots over an area (flush face connections). This is typically done by punching a pattern into steel sheet metal then forging it with a hammer press machine equipped with dies that create raised serrations for clamping parts together securely without welding them permanently together using heat-resistant bolts so they may still be disassembled later if necessary
  • Testing – Flanges must be tested before being used in pipelines as well as after installation to ensure quality standards are met throughout production cycle including inspection process itself!
  • The dimensions and specifications for a flange are contained within a standard developed by ASME B16.5 and ANSI/ASME B16.5-2003 is a standard for pressure piping. The standards contain information on the design, construction and performance of mechanical joint components that are used in many industries including oil, gas, chemical processing, power generation and other related sectors.

With the guidelines outlined above, you will be able to choose the right flange for your specific needs. ANSI/ASME B16.5 is a standard which contains all of these specifications and can be used as a reference tool when choosing flanges for your next project.

How To Order ANSI/ASME B16.5 Flanges

When you want to get a quote or release a PO to us, pls clear the information:
Flange type + RF/RTJ/FF + Class (including pipe SCH for WN and SW flange) + Size + Material + Standard + Order Quantity
For example, you want to buy 500 pcs welding neck flange with raised face for your system and the pipe is 10” SCH40S, pressure rate is class 600 in stainless steel 316L, the piping design is to ASME, so the description would be:

WNRF flange, 10” 600# SCH40S, A182 F316L, ASME B16.5, 500PCS

How to find a suitable flange manufacturer

Finding the right flange manufacturer is not as simple as it sounds. The process requires you to take into account many factors, including: The type of flange you need. Each type has its own advantages and disadvantages, and an experienced flange manufacturer will be able to recommend which type would be best for your application. A manufacturer who can meet your specifications. If possible, find a company that has experience working with the materials that are going into your product (i.e., if they specialize in titanium alloys but your project requires stainless steel). A manufacturer who can deliver on time (and at an acceptable cost). In some instances, it may make sense for you to use a different supplier if speed or price is more important than quality or reputation – but this isn’t always true!

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