What are pipe fittings?
Pipe fittings are essential components used in piping systems to connect different sections of pipes or to change the pipe’s direction, size, or end type. They allow for the controlled flow of fluids and can be used for various applications, including water supply, heating, and industrial processes.
Types of Pipe Fittings
Here are some common types of pipe fittings:
Elbow: Used to change the direction of the flow. They come in different angles like 45°, 90°, and 180°.
- Butt Weld Long Radius 90 Degree Elbow: A butt weld long radius 90-degree elbow is used for 90-degree turn-on piping in a butt weld piping system. Long-radius elbows are preferred due to their low-pressure drop. They can also be cut less if required in the piping layout. Their centerline radius is 1.5 times the nominal pipe diameter. 90-degree elbows with a straight extension at one end (long tangent) are still available in STD weight if required.
- Butt Weld Short Radius 90 Degree Elbow: Butt weld short radius 90-degree elbows are used where space is limited. They are available only at 90 degrees but can be cut to a lesser degree if required, per the piping layout. The centerline radius of short-radius elbows is the same as its nominal pipe diameter.
- Butt Weld Long Radius 45 Degree Elbow: A butt weld long radius 45-degree elbow is used for 45-degree turn on piping in a butt weld piping system. Long radius elbows are preferred due to their low-pressure drop. They can also be cut less if required in the piping layout. Their centerline radius is 1.5 times the nominal pipe diameter. Only long radius 45-degree elbows are available.
- Butt Weld Long Radius Reducing Elbow: Only long radius reducing elbows are available. They are sparingly used where there is a space constraint. Normally a straight elbow with a butt weld reducer is used.
- Butt Weld Long Radius 180 Degree Return: 180-degree returns are used to construct heating coils, tank vents, etc. Long radius returns provide minimum pressure drop.
- Butt Weld Short Radius Returns: 180 degree returns are used to construct heating coils, tank vents, etc. Long radius returns provide minimum pressure drop.
Reducer: Used to reduce the pipe size from a larger to a smaller bore. There are two types:
- Butt Weld Concentric Reducer: These are used preferably in vertical piping. Placing them in horizontal piping changes the elevation of the piping, which can be detrimental. These are normally avoided to reduce inventory, and eccentric reducers are used as much as possible.
- Butt Weld Eccentric Reducers: These are mostly used in place of concentric reducers as they keep the bottom of the pipe unchanged in horizontal piping. To reduce inventory, eccentric reducers are preferred in place of concentric reducers.
Tee: Used to connect three flow sections. They come in different types:
- Butt Weld Straight Tee: Butt weld straight tees are used for branch connections of the same size as the header. These are one of the widely used butt welding fittings.
- Butt Weld Reducing Tee: Butt weld reducing tees are used for branch connections of smaller size than that of header. These are one of the widely used butt welding fittings.
- Reducing Laterals: Reducing laterals is ordered similarly to butt-welding tees, except the angle between branch and run is also stated.
Butt Weld Cross: Used to connect four flow sections.
- Butt Weld Straight Crosses: For economy, availability, and to minimize the number of items in inventory, it is preferred to use tees, etc., and not crosses except where space is restricted, as in marine piping or revamp work.
- Butt Weld Reducing Crosses: For economy, availability, and to minimize the number of items in inventory, it is preferred to use tees, etc., and not crosses except where space is restricted, as in marine piping or revamp work.
Butt Weld Caps: These are used to close the pipe ends on pipe racks. They are also used at the bottom of condensate drip legs. Holes can be drilled on their head, and drain connections can be added in case of drip legs.
- Hemispherical Caps: These have a shape like half of a sphere. They offer minimal resistance to flow and are often used in high-pressure applications.
- Ellipsoidal Caps: These are also known as 2:1 elliptical caps. Their shape is more like an ellipse, and they are the most common type of cap used in the industry. They provide a medium level of resistance to flow.
- Torispherical Caps: These caps combine a sphere and a torus. They have a curved surface and a flat edge. They are often used in medium-pressure applications.
- Flat Caps: As the name suggests, these caps have a flat end. They are used in applications where the pressure is low and the flow resistance doesn’t need to be minimized.
- Conical Caps: These caps have a conical shape and are used in specific applications where the flow needs to be directed or where the cap needs to fit a particular shape.
- Dished Caps: These caps have a dish-like shape. They are often used in pressure vessels.
- Special Custom Caps: Sometimes, custom caps are designed and manufactured based on specific requirements, such as unique shapes, sizes, or materials.
Pipe Bends: 3D, 4D, 5D etc.
Bends are made from straight pipe. Common bending radii are 3 and 5 times the pipe size (3R and 5R bends, where R=Nominal Pipe Size – nominal diameter – not radius). 3R bends are available from stock. Larger bends can be custom made, preferably by hot bending. Only seamless or electric-resistance-welded pipe is suitable for bending.
- 3D Bend: A 3D bend has a bend radius that is 3 times the diameter of the pipe. For instance, if you have a pipe with a diameter of 100 mm, a 3D bend would have a radius of 300 mm.
- 4D Bend: A 4D bend has a bend radius that is 4 times the diameter of the pipe. Using the same example, for a pipe with a diameter of 100 mm, a 4D bend would have a radius of 400 mm.
- 5D Bend: Similarly, a 5D bend has a bend radius that is 5 times the diameter of the pipe. For a 100 mm diameter pipe, the bend radius would be 500 mm.
Lap Joint Stub End: These are used when piping is made of a costly material such as stainless steel. Thick flange slips on this stub end. Flange can be made of a cheaper material like carbon steel. Lap Joint Stub End is a term for a branch pipe welded directly into the side of the main pipe run – it is not fitting. This is the commonest and least expensive method of welding a full-size or reducing branch for pipe 2-inch and larger. A stub-in can be reinforced.
- Type A Stub Ends: This type has a longer radius and is used with standard lap joint flanges. It is the most common type used in piping systems.
- Type B Stub Ends: This type has a shorter radius and is used with long neck lap joint flanges.
MSS SP-43 Stub Ends: This specification covers stub ends in sizes NPS 1/2 through NPS 24 for use with lap joint flanges.
- Short Pattern (MSS-A) Stub Ends: These are the standard stub ends used with standard lap joint flanges.
- Long Pattern (MSS-B) Stub Ends: These have a longer shoulder and are used with long neck lap joint flanges.
ASME B16.9 Stub Ends: This specification covers factory-made wrought butt-welding fittings, including lap joint stub ends. They are available in sizes NPS 1/2 through NPS 48.
Connection methods of pipe fittings
Pipe fittings play the role of connecting, controlling, redirecting, diverting, sealing, and supporting the piping system, in which the main role is to connect the pipe with the pipe. What are the connection methods of pipe fittings? There are 8 kinds of commonly used connection methods:
Welding applies to non-galvanized steel pipe, mostly used for concealed piping and larger diameter piping, and is more commonly used in high-rise buildings. Copper pipe connection can be used for special joints or welding; when the pipe diameter is less than 22mm, socket or casing welding is recommended, the socket should meet the media flow direction installation; when the pipe diameter is greater than or equal to 2mm is recommended to use butt welding. Stainless steel pipe can be socket welding.
2) Groove connection (clamp connection)
Groove-type connector connection can be used for fire water, air conditioning hot and cold water, water supply, rainwater, and other systems with a diameter greater than or equal to 100 mm of steel pipe, with simple operation, does not affect the original characteristics of the pipeline, construction safety, good stability of the system, easy maintenance, labor-saving and time-saving features.
3) Flange connection
Used to connect the larger diameter pipes with flange connection, flange connection is generally used in the main connection valves, check valves, water meters, pumps, etc., as well as the need for frequent disassembly, and maintenance of the pipe section. Welding should be the second galvanized or anti-corrosion for galvanized pipe such as welding or flange connection.
4) Socket welding connection
Socket welding connection is a welding method mainly used to connect light and thin metal plates. In this connection method, a hole is pre-made on one metal piece, and the end of the other metal piece is inserted into this hole and then welded. This welding method can provide good connection strength and be carried out without welding equipment.
5) Threaded connection
Threaded connection is the use of pipe fittings with threaded connections; pipe diameter less than or equal to 100 mm of galvanized steel pipe should be threaded connections, mostly used for open pipe. Steel-plastic composite pipes generally also use threaded connections. Galvanized steel pipe should be a threaded connection, a set of wire buckles when the destruction of the galvanized layer surface and the exposed threaded part should be done to prevent corrosion; flange or ferrule-type special fittings should be used to connect the galvanized steel pipe, and the flange should be galvanized at the weld secondary.
6) Compression connection
Stainless steel clamping pipe connection technology replaces the traditional water supply pipe connection technology such as thread, welding and bonding. It has the characteristics of protecting water quality, strong corrosion resistance and long service life. During construction, the bearing pipe with special sealing ring is connected with the pipe, and the special tool is used to press the pipe mouth to seal and tighten. It has the advantages of convenient installation, reliable connection and economic rationality.
7) Ferrule connection
Aluminum-plastic composite pipes generally use threaded ferrule crimping. The fittings nut set in the pipe end, and then the fittings core into the end, with a wrench to tighten the fittings and nuts can be. A copper pipe connection can also be used for threaded ferrule crimping.
Apply the adhesive evenly on the surface of the socket of the pipe fitting with a brush, then connect the pipes.
What matters should be noted when connecting pipe fittings?
- According to different pipe materials, the construction environment chooses the appropriate connection, such as lower temperatures suitable for hot melt connection, pipe diameter suitable for flange connection, etc.
- Connecting fittings, first ensure that the fittings and their corresponding connection parts of the socket, seals, and other accessories are cleaned up and shall not be attached to the soil, water, and other impurities; if there is dirt attached to the top, it must be wiped with a wet towel before connecting.
- Welding and other methods should be good protective measures to prevent injury to themselves or others.
- Connected fittings can be drawn on both sides of the marking line to prevent the connection process in the future; the fittings fall off, offset, and facilitate future inspection.
When selecting a piping connection, it’s essential to consider the specific requirements of your application, the compatibility of materials, and any regulatory or industry standards that apply. Always consult with a piping engineer or specialist when making a selection to ensure safety and reliability.
Standard for pipe fittings
The standards you’ve mentioned are related to pipe fittings and cover various aspects such as dimensions, materials, and manufacturing processes. Here’s a brief overview of each pipe fitting standard:
- ASME B16.9: This standard covers factory-made wrought buttwelding fittings such as elbows, tees, reducers, and caps. It provides dimensions, tolerances, and testing for these fittings.
- ASME/ANSI B16.5: This standard pertains to pipe flanges and flanged fittings. It provides dimensions, tolerances, and materials for flanges used in piping systems.
- ASTM A105/A105M: This specification covers forged carbon steel piping components for ambient- and higher-temperature service in pressure systems. It includes flanges, fittings, valves, and similar parts.
- ASTM A234/A234M: This specification covers wrought carbon steel and alloy steel fittings of seamless and welded construction for pressure piping and pressure vessel fabrication.
- ASTM A403/A403M: This specification covers the standard for wrought austenitic stainless steel piping fittings for seamless and welded construction.
- ASTM A420/A420M: This specification covers piping fittings of wrought carbon steel and alloy steel for low-temperature service.
- ISO 5251: This international standard establishes the basic dimensions of buttwelding fittings, which are essential for the interchangeability of these components.
- MSS SP-43: These standard covers wrought stainless steel butt-welding fittings for pressure piping and pressure vessel fabrication.
- MSS-SP-97: This standard provides the practices for the design and dimensions of integrally reinforced forged branch outlet fittings of buttwelding, socket welding, and threaded types.
- GOST 17375 (pipe elbow LR): This Russian standard specifies the dimensions and technical requirements for long-radius pipe elbows.
- GOST 30753 (pipe elbow SR): This Russian standard pertains to short-radius pipe elbows, specifying their dimensions and technical requirements.
- GOST 17376 (pipe tee): This standard covers pipe tees’ dimensions and technical requirements.
- GOST 17378 (pipe reducer): This standard specifies the dimensions and technical requirements for pipe reducers.
- GOST 17379 (pipe cap): This standard pertains to pipe caps, specifying their dimensions and technical requirements.
These standards serve a specific purpose in pipe fittings, ensuring that products adhere to consistent quality, dimensions, and performance criteria. If you need detailed information or specific sections from any of these standards, you should refer to the actual standard documentation or consult with Guanxin’s experts.
Materials of pipe fittings
The materials used for steel pipe fittings are chosen based on the application, working conditions, and the properties required.
Here are the common materials used for steel pipe fittings:
Carbon Steel: As the name suggests, it is primarily made of iron and carbon. It’s one of the most common materials used in pipe fittings due to its durability and strength.
- High strength.
- Suitable for high-pressure applications.
- Prone to corrosion if not properly treated.
- Not ideal for highly acidic environments.
Stainless Steel: Stainless steel is an iron, carbon alloy with a minimum of 10.5% chromium. This composition gives it a shiny appearance and resistance to corrosion.
- Highly resistant to corrosion.
- Aesthetically pleasing.
- Durable and long-lasting.
- More expensive than carbon steel.
- Can be prone to staining in certain conditions.
Alloy Steel: Alloy steel is a blend of carbon steel and other alloying elements like chromium, molybdenum, and nickel. These additions enhance its mechanical properties.
- Enhanced strength and hardness.
- Improved resistance to wear and corrosion.
- Versatile applications.
- It can be more expensive than carbon steel.
- Requires careful selection of alloying elements for specific applications.
Duplex & Super Duplex: These are types of stainless steel with a dual-phase structure that combines the best of austenitic and ferritic steels.
- High resistance to corrosion.
- Excellent strength.
- Good weldability.
- More expensive than traditional stainless steel.
- Requires specialized welding techniques.
Nickel Alloys: Nickel alloys are a combination of nickel and other metals designed for specific applications where high corrosion resistance is needed.
- Exceptional resistance to corrosion and oxidation.
- Maintains strength at high temperatures.
- Versatile in various environments.
- It can be not easy to machine.
Copper Alloys: Copper alloys, like bronze and brass, have been used for centuries in pipe fittings. They offer a unique combination of conductivity and corrosion resistance.
- Excellent thermal and electrical conductivity.
- Good corrosion resistance.
- Aesthetically pleasing.
- Softer than steel, leading to potential wear issues.
- Can be expensive.
Titanium Alloys: Titanium alloys are known for their high strength-to-weight ratio and exceptional corrosion resistance.
- Lightweight yet strong.
- Highly resistant to corrosion, especially from seawater.
- Among the most expensive materials.
- Requires specialized machining and welding techniques.
Chemical composition comparison table for martensite, ferrite, austenite, and duplex stainless steel
|Type||Steel number||Grade||Chemical composition%|
|Former Soviet Union||2Cr13Mn9Ni4||0.15-0.25||12.00-14.00||3.70-5.00||8.00-10.00|
|1Cr18Ni11Si4AlTi||0.10-0.18||17.50-19.50||10.–120..||≤0.80||≤0.035||≤0.030||–||3.40-4.00||–||–||Al 0.10-0.30; Ti 0.40-0.70|
|Ferritic steel||405||0Cr13Al||≤0.08||11.50-14.50||3)||≤1.00||≤0.035||≤0.030||–||≤1.00||–||–||Al 0.10-0.30|
Chemical composition list of nickel-based alloys
|Alloy #||Cr||Ni||C||Mn. Max.||Si Max.||P Max.||S Max.||Other Elements|
|Carpenter 20Cb-3||20||35||0.06 Max.||2||1||0.035||0.035||Cu 3.5, Mo 2.5, Nb+Ta 8xC Min/1.0 Max|
|Haynes 25 (L605)||20||10||0.05/0.15||2||1||….||….||Co 50.0, W 15.0|
|Hastelloy B-2||1||68||0.02 Max.||1||0.1||0.04||0.03||Mo 28.0, Co 1.0|
|Hastelloy C-276||15.5||57||0.02 Max.||1||0.08||0.03||0.03||Mo 16.0|
|Hastelloy X||21.8||47.5||0.05/0.15||1||1||0.04||0.03||Mo 9.0, Co 1.5|
|Inconel 600||15.5||76||0.15 Max.||….||….||….||….||……….|
|Inconel 601||23||60.5||0.10 Max.||….||….||….||….||Al 1.00/1.70|
|Inconel 625||21.5||61||0.10 Max.||….||….||….||….||Mo 9.0, Nb+Ta 3.6|
|Inconel 718||19||52.5||0.08 Max.||….||….||….||….||Mo 3.0, Nb+Ta 5.1|
|Incoloy 800||21||32.5||0.10 Max.||….||….||….||….||……….|
|Monel 400||…..||66.5||0.30 Max.||….||….||….||….||Cu 31.5|
|Nickel 200||…..||99.6||0.15 Max.||….||….||….||….||……….|
|Nickel 201||…..||99.6||0.02 Max.||….||….||….||….||……….|
Choosing the right material for your pipe fittings depends on the application. For high-pressure systems, carbon steel might be ideal. If corrosion resistance is a priority, stainless steel or nickel alloys could be the way to go. Always consider the specific needs of your project before making a decision.
Performance requirements for pipe fittings
The basic performance of pipe fittings generally includes the following five aspects: mechanical performance, corrosion resistance, and physical performance.
The ability of a pipe fitting to resist rupture and excessive deformation under external forces.
- Strength index
- Elasticity index
- Plasticity index
- Toughness index
- Fatigue strength
- Fracture toughness
Corrosion Resistance (Chemical Properties):
The ability of pipe fittings to resist corrosion in specific media environments.
- Corrosion can lead to damage to fittings and threaten the safety of pressure pipelines.
- Many pressure pipeline failures are related to the corrosion of pipe fittings.
- Materials in the petrochemical production process can be corrosive to pipe fittings.
- Pipe fittings should avoid stress corrosion.
- Pipe fittings should have resistance to uniform corrosion of the medium.
- More details on this topic will be discussed in the second section of the chapter.
Refers to the inherent physical attributes of pipe fittings.
- Density (g) in kg/m3
- Thermal conductivity (l) in kcal/m.℃.h
- Specific heat in kcal/kg.℃
- Melting point (Tm) in ℃
- Linear expansion coefficient (α) in 1/℃
- Elastic modulus (E)
- Specific gravity (q)
Note: Different usage conditions may require different physical properties.
Comparison Table of Nominal Wall Thickness of Steel Pipe Dimensions Chart ANSI B36.10 & 36.19
|Nominal Pipe Size||Outside Diameter (mm)||Nominal Wall Thickness Schedule T|
|NPS||DN||OD||SCH 5s||SCH 10s||SCH 10||SCH 20||SCH 30||SCH 40s||SCH STD||SCH 40||SCH 60||SCH 80s||SCH XS||SCH 80||SCH 100||SCH 120||SCH 140||SCH 160||SCH XXS|
Manufacturing process of pipe fittings
The pipe fittings production process involves multiple links, including raw material preparation, processing and manufacturing, heat treatment, surface treatment, quality inspection, etc. We will provide a detailed description of the various steps and processes involved in the production process of pipe fittings, ensuring that the process is clear and practical.
(1) Selection of raw materials
The selection of materials is in line with the relevant standards of the pipe producing countries and the owner’s requirements of the raw material standards.
After entering the factory, the inspector first verifies the original material certificate issued by the manufacturer and the material inspection report of the imported manufacturer. Check whether the marking on the material is complete and whether the quality certificate is uniform.
Newly purchased materials into the factory for re-inspection, according to ASME, DIN 17175 standard requirements of the chemical composition of the material, length, wall thickness, outer diameter (inner diameter) and surface quality, and other strict inspection, the material lot number and pipe number and other records. Materials that do not meet the requirements cannot be stored and processed. The inner and outer surfaces of steel pipe are not allowed to have cracks, folding, rolling folds, scars, delamination, and hairline; these defects should be completely removed from the removal of the depth shall not exceed the negative deviation of the nominal wall thickness, the actual wall thickness of its cleanup shall not be less than the minimum value of the wall thickness allowed. On the steel pipe’s internal and external surfaces, the permissible defects’ size should not exceed the relevant provisions of the corresponding standards. Otherwise, it will be rejected. Oxidized skin on the internal and external surfaces of the steel pipe shall be removed, and anticorrosion treatment shall be carried out. The anti-corrosion treatment shall not affect the naked eye appearance inspection and can be removed.
In order to ensure compliance with the indicators specified in the material, the customer’s special requirements of the material should also carry out the following tests.
1) Mechanical properties
Mechanical properties by DIN 17175 and ASME requirements. For alloy steel pipe to do transverse mechanical properties test (including transverse impact test), impact test for Charpy V test, the number of tests with the tensile test.
2) Process performance
Steel pipe root by root according to SEP 1915 to do 100% ultrasonic non-destructive testing and provide ultrasonic testing of the standard specimen, the standard specimen depth of defects for 5% of the wall thickness, and the maximum not exceeding 1.5mm.
Pipe for flattening test 3 actual grain size alloy steel finished tube of the actual grain size should not be coarser than 4 levels, the same furnace number of steel pipe grade difference does not exceed 2 levels, grain size inspection by ASTM I12-95, the number of inspections for each furnace number ten per heat treatment batch once.
(2) Cutting material
In the power plant with high temperature, high-pressure alloy pipe fittings before the material, first of all, after accurate material calculations, according to the results of strength calculations of the fittings to analyze and consider the fittings in the production process of thinning, deformation, and many other factors on the fittings of the key parts (such as elbow arc, tee shoulder thickness, etc.) and the impact of the selection of the material with sufficient margins, and to consider the fittings molding stress enhancement coefficient in line with the design of the pipe stress coefficient and the through-flow area of the pipe and other aspects of the factors. The hot-pressing tee should calculate the pressing process’s radial and shoulder material compensation.
For high alloy pipe materials with a gantry band saw cutting machine, use the cold cutting method of undercutting; for other materials, generally avoid cutting with flame and use band saw cutting to prevent the material in the cutting process of hardened layer or due to improper operation caused by cracks and other defects.
According to the design requirements in the cutting of raw materials in the outer diameter, wall thickness, material, pipe number, furnace batch number, pipe fittings billet flow number, and other contents of good marking transplantation, we are marking the use of low-stress steel seal and paint spraying. In the production operation process flow card records the operation content.
After the first piece of material, the operator self-checks and reports to the testing center’s special inspectors for special inspection after passing the inspection and other pieces of material and each piece of testing and recording.
(3) Pipe fittings hot pressing (push) molding
Pipe fittings (especially tee) and hot pressing molding are important processes; a fuel oil heating furnace can heat the heating of the blank. Before heating the billet, use a hammer, grinding wheel, and other tools to clean the surface of the billet pipe chip angle, oil, rust copper, aluminum, and other low melting point metals. Check whether the marking of the billet meets the design requirements.
Clean the debris in the heating furnace hall, check whether the heating furnace circuit, oil circuit, cart, and temperature measurement system are normal and whether the oil is sufficient.
Place the billet in the heating furnace for heating, application of refractory bricks to make the workpiece in the furnace and the hearth isolation 20, according to different materials to strictly control the heating rate of 150 ℃ / hour, heated to the material AC3 above 30-50 ℃ when the heat preservation is greater than 1 hour. Heating and holding process with digital display or infrared thermometer monitoring, and adjusted at any time.
When the blank is heated to the specified temperature out of the press, pressing with 2500 tons of presses and pipe fittings tire mold to complete the pressing process with an infrared thermometer to measure the temperature of the workpiece pressing process is not less than 850 ° C, when the workpiece is not pressed to meet the requirements of a time and the temperature is too low. The workpiece is back to the furnace for re-heating and heat preservation and then pressed.
Product thermoforming fully considers the finished product molding process of thermoplastic deformation of the metal flow of the law, molding molds trying to workpiece thermal processing of deformation resistance is small, pressing tire molds are in perfect condition, and according to the ISO 9000 quality assurance system requirements for regular verification of the tire molds to control the thermoplastic deformation of the material, so that the pipe fittings at any point on the actual wall thickness are greater than that of the connection of the straight pipe—minimum wall thickness.
For large-diameter elbows, using intermediate frequency heating pushed into shape, pushing the choice of large-scale elbow pushing machine equipment. The pushing process is done by adjusting the power of the medium frequency power supply to adjust the heating temperature of the workpiece, generally controlled at 950-1020 ℃ when pushing, pushing speed control in 60-100 mm/min.
(4) Heat treatment of pipe fittings
For 10CrMo910, 12Cr1MoV, and other materials of the finished product of our company in strict accordance with DIN 17175 and ASME standards in the heat treatment system for heat treatment, general small pipe fittings of the heat treatment of the available resistance furnace, large-diameter pipe fittings or bends can be in the oil heat treatment furnace.
Heat treatment furnace hall clean, no oil, ash, rust, and other metals with different treatment materials.
Strictly according to the “heat treatment process card” requirements of the heat treatment curve for heat treatment, alloy steel fittings control temperature rise and fall rate of less than 200 ℃ / hour.
The automatic recorder records the temperature rise and fall at any time and automatically adjusts the furnace temperature and holding time according to the predetermined parameters; in the pipe fittings heating process, a firewall blocks the flame to prevent the flame from directly sprayed on the surface of the pipe fittings to ensure that the pipe fittings in the heat treatment process do not appear overheating, overcooking and other phenomena.
After heat treatment, alloy pipe fittings should be piece by piece metallographic examination. The actual grain size of the alloy is not coarser than 4 levels; the same furnace number pipe fittings grade difference is at most 2 levels.
Hardness test on the heat-treated pipe fittings to ensure that the hardness value of any one part of the pipe fittings does not exceed the range of standard requirements.
After heat treatment of pipe fittings, remove the oxidized skin on the internal and external surfaces by sandblasting until the metallic luster of the material is visible. Scratches on the material’s surface, pits, and other defects should be grinding wheel, and other tools will be polished smooth; polished pipe fittings’ local thickness shall not be less than the minimum wall thickness required by the design.
Fill in the heat treatment record according to the fittings number and marking, and re-write the incomplete marking on the surface of the fittings and the flow card.
(5) Pipe fittings pickling
Pickling of pipe fittings refers to using an acidic solution to clean the surface of pipe fittings to remove rust, oxidized layer, oil, and other impurities. This process is usually used for metal fittings, especially steel fittings, to improve their surface quality.
The basic steps of the pickling process are as follows:
- Pretreatment: First, the pipe fittings need to be pretreated, such as mechanical grinding or sandblasting, to remove most of the rust and impurities.
- Pickling: The fittings are immersed in an acidic solution. Commonly used acids include sulfuric acid and hydrochloric acid. The acid concentration, temperature, and immersion time will affect the pickling effect.
- Rinsing: Rinse the fittings with clean water to remove all chemical residues.
- Drying: Dry the fittings naturally in an oven or the air.
The pickling process needs to be handled with care as the acidic solution harms the human body and may cause environmental pollution. Therefore, the operator must wear appropriate protective equipment and ensure the work is carried out under well-ventilated conditions. In addition, the used acidic solution must be disposed of properly and cannot be discharged directly into the environment.
(6) Beveling of pipe fittings
The beveling of pipe fittings is carried out by mechanical cutting. Our company has more than 20 sets of machining equipment such as various lathes, power heads, etc., which can be used to process double V-type or U-type bevels and internal bevels of various thick-walled pipe fittings according to the requirements of the DL869 Welding Technical Regulations for Thermal Power Plants, GD87 Typical Design Manual for Steam and Water Pipeline Components and Parts of Thermal Power Plants, DL/T695-1999 Steel Butt-welded Fittings for Power Stations, and the requirements of the bidders. Or U-type beveling and internal and external beveling, the company can be fully by the beveling diagrams provided by the bidder and technical requirements for processing to ensure that the pipe fittings in the welding process facilitate the operation and welding.
The inspector completes Pipe fittings beveling according to the drawing requirements of the pipe fittings’ external dimensions of the test and acceptance for the geometric dimensions of the unqualified products rework until the product meets the design dimensions.
(7) Welding of pipe fittings
For the need to weld the “welded tee,” “welded elbow,” and other fittings welded by professional welders with many years of experience in welding, and according to the requirements of the appropriate welding process assessment, mechanical properties of the weld test, under the guidance of the appropriate process regulations Welding production. Welding process using qualified welding process evaluation, process evaluation in line with the ASME Boiler and Pressure Vessel Code, Volume IX, Welding, and Brazing Process Evaluation, the welders are also assessed as qualified welders. During the welding process, the welder applies items that do not match those for which they are qualified by examination and cannot weld. During the welding process, quality assurance engineers monitor and measure the stopping and witnessing points of the welding process to ensure that no defects or problems occur in the critical welding process. Welding of alloy materials strictly controls welding parameters such as interlayer temperature, preheating temperature, and number of welding layer passes and carries out careful interlayer cleaning. Tempering treatment is carried out immediately after welding to ensure that the performance of welded joints meets the specification requirements.
In strict accordance with the company’s “welding process guide card,” the welding process, the welding process pays attention to avoiding the emergence of non-welded through porosity, folder ballast, cracks, biting, and other defects.
The post-welding heat treatment of the pipe fittings can be carried out in a resistance furnace or fuel oil furnace. Also, it can be carried out in a far-infrared heating furnace to ensure that the welded joints have similar mechanical properties with the base material and other technical indicators.
Welded pipe fittings weld 100% ray or ultrasonic testing, according to JB 4730-2005 standard ultrasound to reach level Ⅰ, ray to reach level Ⅱ qualified.
(8) Inspection of pipe fittings
Before leaving the factory, the pipe fittings are by DL869, DL5031, and other standards that require various tests. According to ASME B31.1, requirements of various tests are recognized by the State Bureau of Technical Supervision with the appropriate qualifications of professional inspectors to complete.
Tee, elbow, size of the outer surface of the magnetic particle (MT) test, the outer arc side of the elbow, tee shoulder and size of the reducer for ultrasonic thickness measurement and flaw detection, welded fittings at the weld for radiographic or ultrasonic flaw detection. Forged tees or elbows are subjected to ultrasonic testing of blanks before machining.
Magnetic particle flaw detection is carried out within 100mm of the bevel of all pipe fittings, and the flaw detection ensures that there are no cracks and other defects caused by the cutting process at the bevel.
Surface quality: the internal and external surfaces of the pipe fittings are not allowed to have cracks, shrinkage holes, cinder, sticky sand, folding, leakage of welding, heavy skin, and other defects; the surface should be smooth, not allowed to have sharp scratches, the depth of the depression is not more than 1.5mm, the maximum size of the depression should not be greater than 5% of the circumference of the pipe, and not greater than 40mm. The surface of the weld shall have no cracks, holes, arc craters, and spatters and shall not be biting edges, the Tee inside the corner of the rounded transition. All pipe fittings do 100% surface appearance inspection. Cracks, sharp corners, pits, and other defects on the surface of the pipe fittings are polished with a sanding machine, and magnetic particle flaw detection is carried out on the grinding place until the defects are eliminated and the thickness of the pipe fittings after grinding is not less than the minimum thickness of the design.
For the special requirements of the customer, pipe fittings should also do the following tests:
All fittings can be tested with the system for hydrostatic test (hydrostatic test pressure of 1.5 times the design pressure, time not less than 10 minutes). The factory fittings need help to do the hydrostatic test regarding complete quality documents.
1）Actual grain size
The actual grain size of the finished pipe fittings should not be coarser than 4 levels, the same furnace number of pipe fittings level difference does not exceed 2 levels, grain size test by YB/T5148-93 (or ASTM E112-95) method, the number of tests for each furnace number + once per heat treatment batch.
Manufacturers should be by GB/T 13298-91 (or the corresponding international standards) of the relevant provisions of the microstructure test and provide microstructure photos, the number of tests for each furnace number + size (diameter × wall thickness) + heat treatment batch once.
(9) Packaging, marking
Pipes need to be coated with an antirust primer on the exterior, and the exterior is painted in different colors according to different tubes. The paint is even, with no bubbles, wrinkles, or skinning, and the bevel is treated with a special antirust agent. Small forged or important pipe fittings are packed in wooden boxes, and large ones are usually packed naked. All pipe fittings of the mouth are used to protect the rubber (plastic) ring to protect the firm protection from damage to the fittings. Ensure that the final shipment of products is without any cracks, scratches, pull marks, heavy skin, sticky sand, interlayer, slag, and other defects. Mark the pressure, temperature, material, caliber, and other fittings specifications at the obvious place of the fittings products. The steel seal adopts a low-stress steel seal.
(10) Fittings shipment
Pipe fittings are shipped according to the needs of the actual situation to choose a qualified mode of transportation; the general domestic pipe fittings are used in the automobile mode of transportation. Requirements for automobile transportation process with high strength soft packaging tape will be fittings and car body firmly bundled together, in the vehicle cannot be other fittings for bumping and friction, and do a good job of rain, moisture-proof measures. In the pipe fittings delivery alloy steel pipe fittings delivery state: normalized + tempered; carbon steel delivery state: normalized.
(11) Available technical documents
Products before delivery, by the provisions of the review of all types of quality records, reports, and technical documents, can be reviewed by the owner before delivery. Documents submitted with the shipment are: quality assurance certificate processed parts of the design parameters, design drawings fittings test reports (including A raw material re-inspection report; B ray detector report; C heat treatment report; D ultrasonic detector report; E magnetic particle detector report; F coloring penetration detector report; G geometric inspection report; H and the user to negotiate all kinds of reports) fittings material and weight of the other necessary documents.
Quality requirements for pipe fittings
Quality requirements for pipe fittings are essential to ensure piping systems’ safety, reliability, and longevity. These requirements can vary based on the specific region or industry’s application, material, and standards. However, some general quality requirements for pipe fittings include:
Fittings should be made from high-quality materials suitable for the intended application.
The material should be free from defects such as cracks, inclusions, and voids.
Material certificates, such as Mill Test Reports (MTRs), should be available to verify the material composition and properties.
Fittings should meet the specified dimensions, including diameter, thickness, and overall length.
Tolerances should be within the limits set by relevant standards.
The internal and external surfaces of the fittings should be smooth and free from defects like burrs, sharp edges, and rough spots.
Surface treatments like galvanizing or painting should be uniform and free from defects.
Fittings should have mechanical properties, such as tensile strength, yield strength, and elongation, that meet or exceed the specifications for the intended application.
Fittings should have a pressure rating suitable for the intended application and be tested to ensure they can handle the specified pressures without failure.
Fittings should be tested for leakage under specified conditions to ensure they are leak-proof.
Role and Uses of Pipe Fittings
Pipe fittings are an important component used to connect and support piping systems, and they are used in a wide range of applications in various fields such as industry, construction, and the home. The roles and uses of pipe fittings are varied, and the specific roles and uses of pipe fittings will be described below from different perspectives.
The role of pipe fittings is mainly reflected in the following aspects:
- Connecting pipes: pipe fittings play the role of connection in the piping system, which can connect different pipes and realize the continuity of the pipeline. Different types of fittings, pipes of different materials, specifications, and uses can be connected to meet the needs of different occasions. Common fittings include elbow, tee, cross, flange, etc.
- Supporting pipes: pipe fittings can be used as supporting devices for pipes, playing the role of fixing and supporting. In a long-distance pipeline system, it is necessary to use pipe fittings for fixed support to ensure the stability and safety of the pipeline. For example, when the pipeline crosses the building, it is necessary to use pipe clamps or hangers to support the pipeline to ensure that it will not be displaced or damaged by external forces.
- Turn the pipeline flow direction: fittings can change the flow direction of the pipeline so that the fluid in the piping system is affected by the design requirements of the flow. For example, the use of elbows can be realized by bending the pipeline so that the fluid can change the flow direction; tees or crosses can be realized by branching or converging the pipeline to facilitate the distribution or collection of fluids.
- Adjustment of flow and pressure: some special types of fittings, such as throttling devices and control valves, can be adjusted through the circulation area and opening to control the flow and pressure. These fittings are widely used in industrial production equipment and fluid control systems to achieve precise flow and pressure control and ensure the production process’s stability and reliability.
The use of pipe fittings is also very wide, mainly including the following aspects:
- Industrial production: In industrial production, pipe fittings are widely used in various piping systems, such as petrochemical, energy, metallurgy, shipbuilding, textile, food and other industries. Different industries and processes have different requirements for pipe fittings and need to choose suitable materials, specifications, and models of pipe fittings to meet the needs of different production processes.
- Construction: In construction, pipe fittings are used to build piping systems for water supply, drainage, heating, ventilation, and air conditioning. They should not only meet the functional requirements of the building but also comply with the requirements of building safety and energy saving. Therefore, when choosing pipe fittings, factors such as the material’s anti-corrosion performance, pressure resistance, and wear resistance need to be considered.
- Family life: In family life, pipe fittings are widely used in systems such as water pipes, gas pipes, and heating pipes. Basic functions such as home water supply, drainage, and heating can be realized using fittings. To ensure family safety and comfort, choosing high-quality fittings and regularly checking and maintaining the piping system is necessary.
How to weld pipe fitting?
Welding pipe fittings is a specialized skill that requires proper training and equipment. Here’s a general overview of the process:
- Always wear appropriate personal protective equipment (PPE), including a welding helmet, gloves, safety glasses, and protective clothing.
- Ensure proper ventilation in the welding area to avoid inhaling harmful fumes.
- Keep a fire extinguisher nearby.
- Clean the Pipe and Fitting: Remove any dirt, grease, or rust from the surfaces to be welded. This can be done using a wire brush or sandpaper.
- Cut the Pipe: If necessary, cut the pipe to the desired length using a pipe cutter or angle grinder.
- Align the Pipe and Fitting: Ensure the pipe and fitting are aligned correctly. Use a welding clamp or fixture to hold them in place.
Choose the Right Welding Method:
- Shielded Metal Arc Welding (SMAW): Commonly known as stick welding, it’s often used for welding pipes because of its versatility.
- Gas Tungsten Arc Welding (GTAW): TIG welding is used for precision welding and when working with thin materials.
- Gas Metal Arc Welding (GMAW): MIG welding is faster than TIG welding but may need to be more precise.
- Tack Weld: Before fully welding, make small tack welds at several points around the fitting to hold it in place.
- Root Pass: This is the first pass crucial for pipe welding. It ensures penetration into the joint.
- Hot Pass: This pass increases the size of the weld and ensures that the root pass is free from any defects.
- Filler Passes: These passes add more material to the weld, ensuring the joint is strong.
- Cap Pass: This final pass gives the weld a smooth finish.
After welding, inspect the weld for defects such as cracks, porosity, or penetration. This can be done visually or using non-destructive testing methods like ultrasonic or X-ray inspection.
- Cooling: Allow the welded joint to cool naturally. Rapid cooling can cause the weld to crack.
- Cleaning: Remove any slag or spatter from the weld using a chipping hammer or wire brush.
- Post-Weld Heat Treatment (PWHT): Depending on the material and application, PWHT may be required to relieve stresses in the weld and improve its mechanical properties.
Keep records of the welding process, including the type of material, welding method, and any inspections or tests performed.
Welding pipe fittings requires a good understanding of welding techniques, materials, and safety practices. If you’re new to welding, consider taking a welding course or seeking guidance from a professional welder.
How to buy the correct pipe fitting?
When selecting pipe components, the following factors need to be considered:
- Purpose: Firstly, it is necessary to clarify the purpose of steel pipe fittings, such as whether they are used to transport water, gas, oil, or other liquids. Different uses may require steel pipe fittings of different materials and specifications.
- Material: There are many types of steel pipe components, such as carbon steel, stainless steel, alloy steel, etc. Choosing the appropriate material can ensure the durability and safety of steel pipe components.
- Specification and size: As needed, select the appropriate diameter, wall thickness, and length. Ensure that the selected specifications and dimensions match the other components connected.
- Interface type: The interfaces of steel pipe fittings include threaded connections, welding, flange connections, etc. Choosing the appropriate interface type can ensure the stability of the connection.
- Pressure level: Select an appropriate pressure level based on the pressure of the conveying medium. Ensure that the steel pipe components can withstand the maximum pressure during operation.
- Manufacturer: Choose a manufacturer with a good reputation and quality assurance. You can view the manufacturer’s qualification certificates, production licenses, etc.
- Price: While ensuring quality, prices from different suppliers can be compared, and products with higher cost-effectiveness can be selected.
- Inspection report: When purchasing, it is required to provide a quality inspection report for the steel pipe components to ensure that the product quality meets the standards.
- Surface treatment: Choose whether surface treatment, such as anti-corrosion and galvanizing, is required depending on the usage environment and requirements.
- Storage and transportation: Ensure that steel pipe components are not damaged during storage and transportation, and avoid using damaged steel pipe components.
In short, when selecting steel pipe components, multiple factors should be considered comprehensively to ensure the selected product is safe and economical. If there are specific application requirements or environmental conditions, consulting professional personnel or manufacturers is recommended.
How to find a suitable pipe fitting manufacturer?
Finding a suitable pipe fitting manufacturer requires considering the following steps:
- Determine Requirements: Firstly, you need to clarify your requirements. This includes pipe fittings’ type, material, specification, quantity, etc. With clear needs, you can find manufacturers more targeted.
- Conduct market research: List potential manufacturers through online searches, industry exhibitions, associations, and recommendations.
- Verification of qualifications: Ensure that the manufacturer has relevant production qualifications and certificates, such as ISO certification, product quality certificates, etc.
- Visit the factory: Visit the manufacturer’s production factory in person or through an agent to understand its production capacity, process flow, quality control, etc.
- Obtain samples: Request manufacturers to provide samples to verify the quality of their products and whether they meet your needs.
- Compare prices and services: After identifying several qualified manufacturers, compare their quotations, delivery times, after-sales service, etc., and choose the one with the highest cost-effectiveness.
- Signing contract: Sign a formal procurement contract with the selected manufacturer, clarifying the rights and obligations of both parties to ensure smooth cooperation.
- Continuous evaluation: During the cooperation process, continuously evaluate the manufacturer’s product quality, delivery time, service, etc., to ensure they always meet your needs.
In addition, it is recommended to consider the price and various factors such as reputation, service, and delivery time when selecting a manufacturer to ensure a long-term stable cooperative relationship.
Why did the customer choose Guanxin’s pipe fitting?
Customers choose Guanxin’s fittings for various reasons, and the following are some common considerations:
- Quality: Guanxin provides high-quality, durable, and reliable pipe fittings.
- Price: Compared to other suppliers, Guanxin offers more competitive prices.
- Service: Guanxin provides high-quality pre-sales and after-sales services, including technical support and quick response.
- Complete variety: Guanxin provides various specifications and types of pipe fittings to meet the needs of different customers.
- Delivery time: Guanxin can deliver on time, ensuring the customer’s project progress is unaffected.
- Word of mouth: Guanxin enjoys a good reputation and customer recommendations in the industry.
- Experience: Guanxin has extensive experience and technical knowledge in pipe fitting manufacturing.
- Customized service: Guanxin can provide customized pipe fittings according to customers’ specific needs.
- Certification and compliance: Guanxin’s products comply with international and domestic standards and certifications.
- Innovation capability: Guanxin continuously develops new products and technologies to meet market changes and new customer needs.
Of course, different customers may choose suppliers based on different considerations. If you would like to know more about your Guangxin’s specific situation, conducting market research or directly inquiring with customers to obtain more specific feedback is recommended.