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A234, A403, A420, A815, B366 BW Fittings: Materials and Specifications

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A complete overview of ASTM materials (as well as the European equivalents) for buttweld fittings: chemical composition, and mechanical properties, of ASTM A234 WPB/WPC (high-temperature CS), ASTM A420 WPL (low-temperature CS), ASTM A860/MSS-SP WPY (high-yield CS), ASTM A234 WPX (alloy steel), ASTM A403 3XX (stainless steel), ASTM A815 (duplex and super duplex), ASTM B366 (nickel alloys).

BUTTWELD FITTINGS MATERIALS

WHAT ARE BW FITTINGS MATERIAL SPECIFICATIONS

The material specifications for BW fittings are critical, as they must match or exceed the performance requirements of the piping system they are integrated into. These specifications ensure that the fittings can withstand the operational pressures, temperatures, and chemical environments they will be exposed to.

Generally speaking, carbon steel buttweld fittings are common for pipelines and process piping in the oil and gas and power generation industry, while stainless steel (and higher grades materials) are used for more demanding applications involving higher temperature, pressure, and corrosion (desalination, pharmaceutical and, food sectors).

ASTM/ASTM SPECIFICATIONS FOR BW FITTINGS

Here’s an overview of common material specifications for buttweld fittings, based on standards from the American Society for Testing and Materials (ASTM) and the American Society of Mechanical Engineers (ASME):

Carbon Steel for High-Temperature Service

ASTM A234 WPB and WPC: This specification covers wrought carbon steel and alloy steel fittings of seamless and welded construction. These fittings are used in moderate and high-temperature service conditions. WPB is the grade for standard carbon steel fittings. WPC is a grade that indicates compliance with a specific chemistry and tensile requirement.

Carbon Steel for Low-Temperature Service Service

ASTM A420 WPL6: This specification covers wrought carbon steel and alloy steel fittings of seamless and welded construction for low-temperature service. The WPL6 grade is specially designed for low-temperature applications, offering excellent toughness.

High Yield Carbon Steel

ASTM A860/MSS SP-75 WPHY 42, WPHY 52, WPHY 60, WPHY 65, and WPHY 70

ASTM A860: ASTM A860 / A860M – Standard Specification for Wrought High-Strength Ferritic Steel Butt-Welding Fittings

  • Scope: This specification covers wrought high-strength low-alloy steel butt-welding fittings of seamless and electric fusion-welded construction for applications in high-pressure gas and oil transmission and distribution systems. It includes fittings of several grades of high-strength low-alloy steel with minimum yield strengths ranging from 42,000 psi (290 MPa) to 80,000 psi (550 MPa).
  • Common Grades: WPHY 42, WPHY 52, WPHY 60, WPHY 65, WPHY 70. The “WPHY” prefix stands for “Wrought Pipe High-Yield,” followed by a number indicating the material’s minimum yield strength in ksi.

MSS-SP:

These specifications from the Manufacturers Standardization Society (MSS) cover high-strength, wrought, high-yield carbon steel buttwelding fittings. The WPHY prefix stands for “Wrought Pipe High-Yield,” followed by a number indicating the minimum yield strength (in thousands of psi) of the material.

Alloy Steel

ASTM A234 WP1, WP5, WP9, WP11, WP22, and WP91: This specification covers alloy steel fittings for high-temperature service. Each WP grade corresponds to a different alloy composition, offering various levels of strength, corrosion resistance, and temperature tolerance.

Stainless Steel

ASTM A403 WP304/L and WP316/L: This specification covers wrought austenitic stainless steel fittings for pressure piping applications. The WP304/L grade is used for fittings made from 304 stainless steel, with the “L” indicating a low carbon content for improved weldability. Similarly, WP316/L refers to low-carbon 316 stainless steel.

Duplex Stainless 

ASTM A815: This is the primary specification that covers wrought ferritic, ferritic/austenitic, and martensitic stainless steel piping fittings, including buttweld fittings. For duplex stainless steel, the specification includes grades such as:

  • S31803 (2205): A standard duplex stainless steel grade with a balanced microstructure of approximately 50% austenite and 50% ferrite. It offers excellent resistance to pitting and crevice corrosion, high strength, and good weldability.
  • S32205: A modified version of S31803, with a higher nitrogen content that enhances its corrosion resistance and strength.

Super Duplex Stainless Steel

ASTM A815: The same specification covers super duplex stainless steel buttweld fittings, with common grades including:

  • S32750 (2507): A super duplex stainless steel that offers exceptional strength and corrosion resistance, making it suitable for demanding applications. It is characterized by its high molybdenum, chromium, and nitrogen content.
  • S32760: Another grade of super duplex stainless steel, known for its excellent corrosion resistance, strength, and toughness. It includes elements such as tungsten and copper for enhanced properties.

Nickel Alloys

ASTM B366: This specification covers nickel alloy fittings for corrosive environments, suitable for a wide range of temperatures and pressures. Common nickel alloys include Inconel, Monel, Hastelloy, and Nickel 200/201, each designed for specific applications where resistance to corrosion and high temperatures is necessary.

The key specifications are reviewed in detail (in terms of chemical composition and mechanical properties) below in this article.

EUROPEAN SPECIFICATIONS FOR BW FITTINGS

These specifications set the standards for dimensions, material grades, mechanical properties, and testing requirements. They are designed to align with European practices and requirements, offering a different set of standards compared to those commonly used in the United States (such as ASTM and ASME). Here’s an overview of key European standards for buttweld fittings:

EN (European Norm) Standards for BW Fittings

  • EN 10253-1 and EN 10253-2: These are the primary European standards for buttweld fittings. EN 10253-1 covers buttwelding pipe fittings made of carbon steel without specific inspection requirements, while EN 10253-2 specifies fittings made of non-alloy and ferritic alloy steels with specific inspection requirements. This standard includes details on type A (reduced load factor) and type B (full load factor) fittings, material grades, mechanical properties, dimensions, and tolerances.
  • EN 10253-3 and EN 10253-4: These parts of EN 10253 specify the requirements for austenitic and austenitic-ferritic (duplex) stainless steel fittings. EN 10253-3 deals with fittings without specific inspection requirements, and EN 10253-4 includes fittings with specific inspection requirements.

Material Grades

European standards specify various material grades for different types of steel, including carbon steel, alloy steel, stainless steel, and duplex stainless steel. These materials are designated by their chemical composition and mechanical properties, ensuring suitability for specific applications and environments. For example:

  • P235GH, and P265GH: Common grades for carbon steel fittings, suitable for moderate to high-temperature applications.
  • 16Mo3, 13CrMo4-5, 10CrMo9-10: Alloy steels for higher temperature and pressure applications.
  • 1.4307, 1.4404 (equivalent to SS 304L and 316L): Stainless steels for corrosion-resistant applications.
  • 1.4462 (equivalent to S31803/S32205): A duplex stainless steel grade for applications requiring high strength and corrosion resistance.

Dimensions and Tolerances

EN standards provide detailed dimensions and tolerances for buttweld fittings, ensuring compatibility and interchangeability across European-manufactured piping components. These specifications cover a wide range of sizes and pressure ratings, accommodating various industrial applications.

Testing and Certification

To comply with European specifications, buttweld fittings undergo stringent testing and quality assurance procedures, including dimensional checks, mechanical testing, and non-destructive testing (NDT). Manufacturers must also meet the requirements of the Pressure Equipment Directive (PED) if the fittings are to be used in pressure applications, which involves additional testing and certification to ensure safety and performance.

European standards for buttweld fittings are essential for harmonizing the manufacturing, testing, and application of piping components across the EU, ensuring high quality, reliability, and safety in industrial piping systems.

MATCH PIPE & BW FITTINGS MATERIALS

It’s crucial to understand that the material composition of both the pipe and the buttweld fitting must be compatible; for instance, an ASTM A106 Gr. B pipe should be coupled with an ASTM A234 WPB buttweld fitting, while an ASTM A312 T304 pipe needs to be joined to an ASTM A403 WP304 fitting, etc.

Mixing materials between pipes and buttweld fittings is neither allowed nor safe. Similarly, the size of the buttweld fitting must correspond exactly to the size of the pipe it connects to.

This basic rule applies to both ASTM/ASME BW pipe fittings and their EN (European) equivalents.

In the piping materials compatibility table, also called the “piping materials matching table”, we present the precise correlation in material grades between pipes, fittings, flanges, and other components used in piping systems.

BW FITTINGS MATERIAL SELECTION

When selecting BW fittings, it’s crucial to consider the specific requirements of your application, including:

  • Temperature and Pressure Ratings: Ensure the material can withstand the operational pressures and temperatures.
  • Corrosion Resistance: Choose materials that are resistant to the types of corrosives that will be encountered.
  • Compatibility: The material of the fittings must be compatible with the piping system to prevent galvanic corrosion and ensure a cohesive system.

Compliance with these material specifications ensures that buttweld fittings will perform reliably in their intended applications, providing a safe and efficient piping system.

CHEMICAL AND MECHANICAL PROPERTIES OF ASTM/ASME FITTINGS

HIGH-TEMP CARBON/ALLOY STEEL BW FITTINGS (ASTM A234)

ASTM A234 carbon steel buttweld fittings are designated for use in moderate and high-temperature service applications for pressure piping systems. This specification covers wrought carbon steel and alloy steel fittings of seamless and welded construction. These fittings are primarily used in the construction of industrial pipelines that transport fluids, including oil, gas, steam, water, and air, under elevated temperatures and pressure conditions.

The ASTM A234 specification covers carbon steel and alloy steel pipe fittings (butt weld) for high-temperature service (carbon steel and alloy steel):

  • ASTM A234 WPA, WPC and, WPC fittings match ASTM A53, ASTM A106 and, API 5L Gr. B pipes.
  • ASTM A234 WP1 to WP91 specifies butt weld fittings for ASTM A335 chrome-moly pipes (low-alloy steel).
  • ASTM A420 WPL covers low-temperature carbon steel butt weld fittings to match ASTM A333 Gr.3 and ASTM A333 Gr. 6 pipes.
  • ASTM A860 specification (WPHY42, WPHY52, WPHY56, WPHY60) covers high-yield wrought carbon steel fittings that match high-yield API 5L Gr. X42, X52, X56, X60 pipes.

Pipe Fittings Materials: ASTM A234 for Carbon and Alloy Steel Butt Weld Fittings

ASTM A234 Chemical Composition

Chemical composition of ASTM A234 Carbon and Alloy Steel Fittings
GradeCMnP maxS maxSiCrMoNiCuOthers
WPB
(1,2,3,4,5)
0.30
max
0.29-1.060.0500.0580.10
min
0.40
max
0.15
max
0.40
max
0.40
max
V 0.08
max
WPC
(2,3,4,5)
0.35
max
0.29-1.060.0500.0580.10
min
0.40
max
0.15
max
0.40
max
0.40
max
V 0.08
max
WP10.28
max
0.30-0.900.0450.0450.10-0.500.44-0.65
WP12 CL10.05-
0.20
0.30-0.800.0450.0450.60
max
0.80-1.250.44-0.65
WP12 CL20.05-
0.20
0.30-0.800.0450.0450.60
max
0.80-1.250.44-0.65
WP11 CL10.05-
0.15
0.30-0.600.0300.0300.50-1.001.00-1.500.44-0.65
WP11 CL20.05-
0.20
0.30-0.800.0400.0400.50-1.001.00-1.500.44-0.65
WP11 CL30.05-
0.20
0.30-0.800.0400.0400.50-1.001.00-1.500.44-0.65
WP22 CL10.05-
0.15
0.30-0.600.0400.0400.50
max
1.90-2.600.87-1.13
WP22 CL30.05-
0.15
0.30-0.600.0400.0400.50
max
1.90-2.600.87-1.13
WP5 CL10.15
max
0.30-0.600.0400.0300.50
max
4.0-6.00.44-0.65
WP5 CL30.15
max
0.30-0.600.0400.0300.50
max
4.0-6.00.44-0.65
WP9 CL10.15
max
0.30-0.600.0300.0301.00
max
8.0-10.00.90-1.10
WP9 CL30.15
max
0.30-0.600.0300.0301.00
max
8.0-10.00.90-1.10
WPR0.20
max
0.40-1.060.0450.0501.60-
2.24
0.75-1.25
WP910.08-
0.12
0.30-0.600.0200.0100.20-0.508.0-9.50.85-1.050.40
max
V 0.18- 0.25
Nb 0.06-0.10
N 0.03-0.07
Al 0.02 max(6)
Ti 0.01 max(6)
Zr 0.01 max(6)
WP9110.09-
0.13
0.30-0.600.0200.0100.10-0.508.0-9.50.90-1.100.40
max
V 0.18-0.25
Nb 0.060-0.10
N 0.04-0.09
Al 0.02 max(6)
B 0.0003-0.006
W 0.90-1.10
Ti 0.01 max(6)
Zr 0.01 max(6)

Notes:

  1. Fittings from bar or plate 0.35 max carbon.
  2. Fittings from forgings 0.35 max Carbon and 0.35 max Silicon with no minimum.
  3. For each reduction of 0.01% below the specified Carbon maximum, an increase of 0.06% Manganese above the specified maximum is permitted, up to a maximum of 1.35%.
  4. The sum of Cu, Ni, Niobium, and Moly shall not exceed 1.00%.
  5. The sum of Niobium and Moly shall not exceed 0.32%.
  6. This applies to heat and product analyses

ASTM A234 Mechanical Properties

Tensile and Yield Strength ASTM A234 for Carbon and Alloy Steel FittingsWPBWPC,
WP11-CL2
WP11-CL1,
WP22-CL1
WP5-CL1
WP9-CL1
WP11-CL3,
WP22-CL3
WP5-CL3
WP9-CL3
WP91
Tensile strength, minimum unless a range is given ksi (MPa)60 (415)70 (485)60 (415)75 (520)90 (620)
Yield strength, min ksi (MPa) (0.2% offset or 0.5% extension under-load)35 (240)40 (275)30 (205)45 (310)60 (415)
Elongation ASTM A234 for Carbon and Alloy Steel FittingsWPB,
WPC, WP11, WP22
WP91
 Longitud.TransverseLongitud.Transverse
Standard
round specimen, or small proportional specimen, min % in 4 D
22142013
Rectangular specimen for wall thickness 5/16″ and over, and
for all small sizes tested in full section; min % in 2 in.
3020
Rectangular specimen for wall thickness less than 5/16″;
min % in 2 in (1/2″ wide specimen)
see note

Note:  For each 0.79 mm decrease in wall thickness below 7.94 mm, a deduction of 1.5 % for longitudinal and 1.0 % for transverse from standard values is permitted

LOW-TEMP CARBON/ALLOY STEEL BW FITTINGS (ASTM A420)

ASTM A420 carbon steel buttweld fittings are specifically designed for low-temperature service. This standard covers wrought carbon steel and alloy steel fittings of seamless and welded construction, intended for use in pressure piping and pressure vessel service at low temperatures. The use of ASTM A420 fittings is crucial in environments where the material must exhibit toughness and durability despite the cold conditions.

ASTM A420 Chemical Composition

Chemical Composition of ASTM A420
ElementsWPL6, %WPL9, %WPL3, %WPL8, %
Carbon [C]≤0.30≤0.20≤0.20≤0.13
Manganese [Mn]0.50-1.350.40-1.060.31-0.64≤0.90
Phosphorus [P]≤0.035≤0.030≤0.05≤0.030
Sulfur [S]≤0.040≤0.030≤0.05≤0.030
Silicon [Si]0.15-0.400.13-0.370.13-0.37
Nickel [Ni]≤0.401.60-2.243.2-3.88.4-9.6
Chromium [Cr]≤0.30
Molybdenum [Mo]≤0.12
Copper [Cu]≤0.400.75-1.25
Columbium [Cb]≤0.02
Vanadium[V]≤0.08

ASTM A420 Mechanical Properties

ASTM A420/ A420MTensile Strength, min.Yield Strength, min.Elongation %, min
GradeksiMPaksiMPaLongitudinalTransverse
WPL665-95415-655352402212
WPL963-88435-6104631520
WPL365-90450-620352402214
WPL8100-125690-8657551516

ASTM A420 Impact Test Properties

Charpy Impact Requirements for WPL6, WPL9, and WPL3
Size of SpecimenA*B*
mmft·lbfJft·lbfJ
10 by 10.01317.61013.6
10 by 7.51013.6810.8
10 by 5.079.557.0
10 by 2.545.434.1

A*Charpy V-Notch Impact Value Required for Acceptance (Average of Three Specimens)
B*Minimum Charpy V-Notch Impact Value Without Requiring Retest (One Specimen Only of a Set)

Charpy Impact Requirements for WPL8
Size of SpecimenA*B*
mmft·lbfJft·lbfJ
10 by 10.025.033.920.027.1
10 by 7.521.028.517.023.1
10 by 5.017.023.114.019.0
10 by 2.58.010.86.08.1

A*Charpy V-Notch Impact Value Required for Acceptance (Average of Three Specimens)
B*Minimum Charpy V-Notch Impact Value Without Requiring Retest (One Specimen Only of a Set)

Impact Test Temperature
Grade°F [°C]
WPL6−50 [−45]
WPL9−100 [−75]
WPL3−150 [−100]
WPL8−320 [−195]

HIGH-YIELD CARBON/ALLOY STEEL BW FITTINGS (ASTM A860)

ASTM A860 carbon steel buttweld fittings are designed for high-strength, high-pressure applications, particularly in the oil and gas industry. This specification covers wrought high-strength ferritic steel butt-welding fittings of seamless and electric fusion-welded construction. These fittings are intended for use in high-pressure gas and oil transmission and distribution systems.

Selection Considerations

  • Matching Pipe Material: The material of the fittings must be compatible with the high-strength pipe material used in the pipeline to ensure a cohesive system capable of handling the intended pressures and loads.
  • Charpy V-Notch Impact Testing: ASTM A860 fittings are subject to impact testing to ensure their toughness, especially important in low-temperature environments or sour service applications.
  • Chemical Compatibility: The fittings must be chemically compatible with the substances being transported to prevent corrosion and degradation that could compromise the pipeline’s integrity.

ASTM A860 Chemical Composition

The Chemical Composition of ASTM A860, %
Carbon≤0.20*A
Manganese1.00-1.45
Phosphorus≤0.030
Sulfur≤0.010
Silicon0.15-0.40*B
Nickel≤0.50*C
Chromium≤0.30*C
Molybdenum≤0.25*C
Copper≤0.35*C
Titanium≤0.05
Vanadium≤0.10
Columbium≤0.04
Vanadium plus Columnium≤0.12
Aluminum≤0.06

*The carbon equivalent C.E.=C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15 shall not exceed 0.42%.
*B If vacuum carbon deoxidation is used, silicon shall not exceed 0.10% by heat analysis and 0.12% by-product analysis.
*C The sum of Ni+Cr+Mo+Cu shall not exceed 1.0%.

ASTM A860 Mechanical Properties

ASTM A860/ 860MYield Strength, min.Tensile StrengthElongation, min.Cv, avg./min.
GradeksiMPaksiMPa%ft*lbsJ
WPHY 424229060-85415-5852530/2540/34
WPHY 464631563-88435-6052530/2540/34
WPHY 525236066-91455-6252530/2540/34
WPHY606041575-100515-6902030/2540/34
WPHY 656545077-102530-7052030/2540/34
WPHY 707048580-105550-7252030/2540/34

*1. The actual yield strength shall not exceed the specified minimum by more than 15 ksi [105 MPa].
*2. The elongation values shall be measured based on the standard round specimens, or small-size proportional specimens, in 4D.
*3. The size of Charpy V-notch specimens shall be 10×10 mm while the impact-test temperature shall be −50°F[−46°C].
*4. All fittings of ASTM A860 shall have a maximum hardness of 22 HRC(235 HBW).

STAINLESS STEEL BW FITTINGS (ASTM A403)

ASTM A403 stainless steel buttweld fittings are specifically designed for use in piping systems where corrosion resistance is a primary concern. This specification covers wrought austenitic stainless steel fittings of seamless and welded construction.

These fittings are intended for use in moderate and high-temperature service conditions, and they are suitable for a wide range of applications due to their excellent resistance to corrosive environments and their ability to withstand high temperatures.

The ASTM A403 specification covers austenitic stainless steel butt weld fittings to match ASTM A312 TP304, TP316, TP321, etc., pipes.

Pipe Fittings Materials: ASTM A430 for stainless steel pipe fittings

ASTM A403 Chemical Composition

GradeUNSCMnPSSiNiCrMoTiNOthers
WPXM-19S209100.064.0-6.00.0450.03111.5-13.520.5-23.51.50-3.00.20-0.40
WP304S30400.0820.0450.0318.0-11.018.0-20.0
WP304LS304030.030
(4)
20.0450.0318.0-12.018.0-20.0
WP304HS304090.04-0.1020.0450.0318.0-11.018.0-20.0
WP304NS304510.0820.0450.0318.0-11.018.0-20.00.10-0.16
WP304LNS304530.0320.0450.0318.0-11.018.0-20.00.10-0.16
WP309S30900.220.0450.03112.0-15.022.0-24.0
WP310SS31080.0820.0450.03119.0-22.024.0-26.0
WPS31254S312540.0210.030.010.817.5-18.519.5-20.56.0-6.50.18-0.22Cu0.50-1.0
WP316S31600.0820.0450.03110.0-14.016.0-18.02.0-3.0
WP316LS316030.030 align=”center”(4)20.0450.03110.0-14.0
(5)
16.0-18.02.0-3.0
WP316HS316090.04-0.1020.0450.03110.0-14.016.0-18.02.0-3.00.10-0.16
WP316NS316510.0820.0450.03110.0-13.016.0-18.02.0-3.00.10-0.16
WP316LNS316530.0320.0450.03110.0-13.016.0-18.02.0-3.00.10-0.16
WP317S31700.0820.0450.03111.0-15.018.0-20.03.0-4.0
WP317LS317030.0320.0450.03111.0-15.018.0-20.03.0-4.0
WPS31725S317250.0320.0450.03113.5-17.518.0-20.04.0-5.00.2
WPS31726S317260.0320.0450.03113.5-17.517.0-20.04.0-5.00.10-0.20
WPS31727S317270.0310.030.03114.5-16.517.5-19.03.8-4.50.15-0.21Cu2.8-4.0
WPS32053S320530.0310.030.01124.0-26.022.0-24.05.0-6.00.17-0.22
WP321S32100.0820.0450.0319.0-12.017.0-19.0-6
WP321HS321090.04-0.1020.0450.0319.0-12.017.0-19.0-7
WPS33228S332280.04-0.0810.020.0150.331.0-33.026.0-28.0Ce 0.05-0.10 Al 0.025Nb 0.6-0.10
WPS34565S345650.035.0-
7.0
0.030.01116.0-18.023.0-25.04.0-5.00.40-0.60Nb 0.10
WP347S34700.0820.0450.0319.0-12.017.0-19.0
WP347HS347090.04-0.1020.0450.0319.0-12.017.0-19.0
WP348S34800.0820.0450.0319.0-12.017.0-19.0Nb+Ta= 103(C)-1.10Ta 0.10Co 0.20
WP348HS348090.04-0.1020.0450.0319.0-12.017.0-19.0Nb+Ta= 83(C)-1.10Ta 0.10Co 0.20
WPS38815S388150.0320.040.025.5-
6.5
13.0-17.013.0-15.00.75-1.50Cu 0.75-1.50Al 0.30

Notes:

  1. Maximum, if not otherwise indicated.
  2. The method of analysis for Nitrogen is agreed between the purchaser and manufacturer.
  3. Niobium 0.10-0.30%; Vanadium, 0.10-0.30%.
  4. For small diameter or thin walls, a Carbon maximum of 0.040% is mandatory in grades TP304L and TP316L. Small outside diameter tubes are those less than 0.50 in. [12.7 mm] 5) in outside diameter and light wall tubes as those less than 0.049 in. [1.24 mm] in average wall thickness.
  5. On pierced tubing, the Nickel may be 11.0-16.0%.
  6. 5 X (C+N2)-0.70.
  7. 4 X (C+N2) -0.70.
  8. The Niobium % shall be ten times above the Carbon content and not more than 1.10%.
  9. The Niobium % shall be eight times above the Carbon content and not more than 1.10%.

ASTM A403 Mechanical Properties

Tensile and Elongation Requirements ASTM A403WP304, WP316WP304L, WP316L
Yield Strength, min, ksi [MPa]30 [205]25 [170]
Tensile Strength, min, ksi [MPa]75 [515]70 [485]
ElongationLongitudinal2828
Transverse2020

DUPLEX/ SUPER DUPLEX BW FITTINGS (ASTM A815)

ASTM A815 duplex steel buttweld fittings are specifically designed for applications that require exceptional strength and corrosion resistance. These fittings are made from duplex stainless steel, a family of stainless steels that combine the properties of austenitic (300 series) and ferritic (400 series) stainless steels.

Duplex stainless steel offers high resistance to corrosion, particularly pitting and crevice corrosion, and exhibits greater tensile and yield strength compared to standard austenitic stainless steel.

The ASTM A815 specification covers duplex and super duplex butt weld fittings to match ASTM A790 and ASTM A928 pipes. These special grades of stainless steel are used for various chemical processes,  piping, oilfield piping and heat exchangers, and flue gas desulfurization processes.

Pipe Fittings Materials: ASTM A815 for Duplex and Superduplex Pipe Fittings

Duplex stainless steel has the following advantages over Series 300 standard SS: 

  • Good general corrosion resistance and high strength
  • Higher resistance to chloride stress corrosion cracking
  • Resistance to chloride pitting and crevice corrosion
  • Good sulfide stress corrosion resistance
  • Easy to weld and conform

UNS S31803, UNS S32205 Chemical Composition (Duplex)

GradeCMnSiPSCrMoNiNFe
S318030.030 max2.00 max1.00 max0.030 max0.020 max22.0 – 23.03.0 – 3.54.50 – 6.500.14 – 0.2063.72 min
S322050.030 max2.00 max1.00 max0.030 max0.020 max21.0 – 23.02.50 – 3.504.50 – 6.500.8 – 0.2063.54 min

UNS S31803, UNS S32205 Mechanical Properties (Duplex)

GradesDensity (g/cm 3)Density (lb/in 3)Melting Point (°C)Melting Point (°F)
S31803 / S322057.8050.2851420 – 14652588 – 2669

UNS S32750, UNS S32760 Chemical Composition (Super Duplex)

GradeCMnSiPSCrMoNiNFe
S 327500.030 max1.20 max0.80 max0.035 max0.020 max24.00 – 26.003.00 – 5.006.00 – 8.000.24 – 0.3258.095 min
S 327600.05 max1.00 max1.00 max0.030 max0.010 max24.00 – 26.003.00 – 4.006.00 – 8.000.20 – 0.3057.61 min

UNS S32750, UNS S32760 Mechanical Properties (Super Duplex)

GradesDensity (g/cm 3)Density (lb/in 3)Melting Point (°C)Melting Point (°F)
S32750 / S327607.80.28113502460

NICKEL ALLOY BW FITTINGS (ASTM B366)

ASTM B366 nickel alloy buttweld fittings are specifically designed for use in applications that require a high degree of corrosion resistance, strength at elevated temperatures, and in certain cases, unique magnetic or thermal expansion characteristics. These fittings, made from nickel-based alloys, are suitable for severe operational environments found in various industries.

Nickel alloy buttweld fittings are selected for the most challenging conditions across various industries, and utilized in situations where less durable materials might not perform adequately.

The ASTM B366/SB 366 specification covers these high-alloy grades buttweld fittings (super-alloys) such as Inconel, Incoloy, Hastelloy, Monel, and the others listed in the table below. The MSS-SP 43 specification, instead, covers the dimensions and the tolerances of nickel alloy buttweld fittings.

Nickel-Alloy Buttweld Fittings Grades

NameUNSDINMatching Pipe GradeEquivalent Forged Grade
904LN089041.4539B677/B673B649
Alloy 020N080202.466B729/B464B462
Alloy 230N06230B622/B619B564
Alloy 400 (Monel)N044002.436B165/B725B564
Alloy 59N060592.4605B622/B619B564
Alloy 600 (Inconel)N066002.4816B167/B517B564
Alloy 625 (Inconel)N066252.4856B444/B705B564
Alloy 800 (Incoloy)N088001.4558B407/B514B564
Alloy 800H (Incoloy)N088101.4958B407/B514B564
Alloy 800HT (Incoloy)N088111.4959B407B564
Alloy 825 (Incoloy)N088252.4858B423/B705B564
Alloy BN10001B622/B619
Alloy B2 (Hastelloy)N106652.4617B622/B619
Alloy B3 (Hastelloy)N10675B622/B619B564
Alloy C22 (Hastelloy)N060222.4602B622/B619B564
Alloy C276 (Hastelloy)N102762.4819B622/B619B564
Alloy C4N064552.461B622/B619
Alloy G-3N069852.4619B622/B619
Alloy G30N06030B622/B619
Alloy K500 (Monel)N055002.4375B865
Nickel 200N022002.4066B161/B725B564
Nickel 201N022012.4068B161/B725

Nickel-Alloy Buttweld Fittings Chemical Composition

FeCNiCrMoCoCuMnSSiWVPAlTi
Nickel 200.40 max.15 max99.0 min.25 max.35 max.01 max.35 max
Nickel 201.40 max.02 max99.0 min.25 max.35 max.01 max.35 max
Hastelloy C2764.0-7.0.01 maxRemainder14.5-16.515.0-17.02.5 max1.0 max.03 max.08 max3.0-4.5.35 max.04 max
Inconel 6006.0-10.0.15 max72.0 min*14.0-17.0.50 max1.00 max.015 max.50 max
Inconel 601140.0561.522.50.30.21.4
Inconel 6255.0 max.10 maxRemainder20.00-30.008.0-10.01.0 max**.50 max.015 max.50 max.015 max.40 max.40 max
Inconel 718Remainder.08 max50.00-55.0017.00-21.002.80-3.301.00 max.30 max.35 max.015 max.35 max.015 max.20-.80.65-1.15
Incoloy 80039.5 min.10 max30.0-35.019.0-23.0.15-.60.15-.60
Incoloy 800H39.5 min.05-.1030.0-35.019.0-23.0.15-.60.15-.60
Incoloy 800HT39.5 min.06-.1030.0-35.019.0-23.0.25-.60.25-.60
Incoloy 82522.0 min0.05 max38.0-46.019.5-23.51.5-3.01.0 max0.03 max0.5 max0.2 max.6-1.2
Alloy 20Balance.07max32.00-38.0019.0-21.02.0-3.03.0-4.02.0max.035max1.0max.045max
Monel K5002.0 max.25 max63.0-70.0Remainder1.5 max.01 max.50 max2.30-3.15.35-.85

Typical Applications for Nickel Alloy Materials (Oil & Gas)

Nickel AlloyTypical Application Area in Oil & Gas Engineering
Nickel 200/201
  • Marine and offshore engineering
  • Caustic handling equipment
  • Manufacture and handling of sodium hydroxide
  • Reactors and vessels where fluorine reacts with hydrocarbons
Hastelloy C-276
  • Pollution control stack liners, ducts, dampers, scrubbers, stack-gas reheaters, fans, and fan housings
  • Flue gas desulfurization systems
  • Chemical processing components like heat exchangers, reaction vessels, evaporators, and transfer piping
  • Sour gas wells
Monel K500
  • Sour-gas service applications
  • Oil and gas production safety lifts and valves
  • Oil well tools and instruments like drill collars
  • Oil well industry
  • Chains, cables, springs, valve trim, fasteners for marine service
Monel 400
  • Marine engineering
  • Chemical and hydrocarbon processing equipment
  • Gasoline and freshwater tanks
  • Crude petroleum stills
  • De-aerating heaters
  • Boiler feed water heaters and other heat exchangers
  • Valves, pumps, shafts, fittings, and fasteners
  • Industrial heat exchangers
  • Chlorinated solvents
  • Crude oil distillation towers
Incoloy 800H/HT
  • Ethylene furnace quench boilers
  • Hydrocarbon cracking
  • Valves, fittings, and other components are exposed to corrosive attack from 1100-1800° F
  • Industrial furnaces
  • Heat-treating equipment
  • Chemical and petrochemical processing
  • Super-heaters and re-heaters in power plants
  • Pressure vessels
  • Heat exchangers
Incoloy 825
  • Chemical Processing
  • Pollution-control
  • Oil and gas well piping
  • Nuclear fuel reprocessing
  • Components in Pickling equipment like heating coils, tanks, baskets, and chains
  • Acid production
Inconel 600
  • Chemical industry
  • Heat treating industry
  • Nuclear Engineering
  • Gas turbine components
Inconel 601
  • Chemical Processing
  • Aerospace
  • Heat treating industry
  • Power generation
  • Heat-treating muffles and retorts
  • Radiant tubes
  • Catalyst support grids in nitric acid production
  • Steam superheater tube supports
Inconel 625
  • Specialized seawater equipment
  • Chemical process equipment
Inconel 718
  • Chemical processing
  • Pollution-control equipment
  • Nuclear reactors
  • Cryogenic storage tanks
  • Valves, fasteners, springs, mandrels, tubing hangers
  • Wellhead completion equipment and blow out preventers (BOPS)

COATED, LINED AND CLAD BW FITTINGS

Coated, lined, and clad buttweld (BW) fittings are specialized types of pipe fittings designed to enhance corrosion resistance, and durability, and ensure the safe transport of corrosive or high-purity substances. These modifications extend the life of fittings and piping systems, reduce maintenance costs, and improve overall system reliability. Understanding the distinctions between coated, lined, and clad fittings can help in selecting the right type for specific applications.

Example of clad tee

Coated Buttweld Fittings

Definition:

  • Coated fittings have a protective layer applied to their exterior and/or interior surfaces. This coating is meant to prevent corrosion, reduce wear, and sometimes prevent fouling. Common coatings include epoxy, zinc, and polyethylene.

Applications:

  • Used in environments where the piping system is exposed to corrosive agents, soil, or water that could damage the metal. Coatings are also used to prevent contamination in systems transporting potable water or sensitive fluids.

Lined Buttweld Fittings

Definition:

  • Lined fittings are manufactured with an inner lining of a different material that is resistant to corrosion, abrasion, or chemical attack. The lining material, often a type of plastic such as PTFE (Polytetrafluoroethylene), PFA (Perfluoroalkoxy), or rubber, serves as a barrier between the fluid and the metal of the fitting.

Applications:

  • Ideal for conveying corrosive chemicals, acids, and high-purity substances. Lined fittings are commonly used in the chemical processing industry, pharmaceutical manufacturing, and food processing where cleanliness and corrosion resistance are critical.

Clad Buttweld Fittings (CRA)

Definition:

Clad fittings are made by bonding a layer of corrosion-resistant alloy (CRA) to the base metal, which is typically carbon steel. The cladding process can involve welding or metallurgical bonding techniques, resulting in a fitting that combines the mechanical strength of the base metal with the corrosion resistance of the cladding material. Common cladding materials include stainless steel, Inconel, and Hastelloy.

Applications:

Utilized in severe corrosive environments, such as in offshore oil and gas production, petrochemical plants, and desalination facilities. Clad fittings are chosen for applications where the full body of the fitting requires protection from aggressive media, not just the surface.

Key Considerations

  • Selection: The choice between coated, lined, or clad BW fittings depends on the specific operational requirements, including the type of media being transported, the environmental conditions, and the required service life of the piping system.
  • Cost-effectiveness: While these fittings may have a higher upfront cost compared to standard fittings, their extended lifespan and reduced maintenance requirements can make them cost-effective in the long term for demanding applications.
  • Compatibility: It’s essential to ensure that the coating, lining, or cladding material is chemically compatible with the substance being transported to prevent degradation and ensure the integrity of the piping system.

In summary, coated, lined, and clad buttweld fittings offer enhanced protection against corrosion, abrasion, and chemical attack, extending the durability and reliability of piping systems in challenging industrial applications.

EUROPEAN VS. ASTM/ASME BW FITTINGS

The table shows the equivalent ASTM and European pipe fittings materials grades.

Butt Weld Fittings Materials Comparison Chart
Werkstoff NumberEuropean GradeASTM Grade
CARBON STEEL FITTINGS MATERIALS
1.0254 St 37.0S235
– –
1.0305 St 35.8/IP235GH (1.0345)A 234 Grade WPA
1.0305 St 35.8/IIIP235GH (1.0345)
1.0405 St 45.8/IP265GH (1.0425)A 234 Grade WPB
1.0405 St 45.8/IIIP265GH (1.0425)
ALLOY STEEL FITTINGS MATERIALS
1.5415 15 Mo 316Mo3A 234 Grade WP1
1.7335 13 CrMo 4 413CrMo4-5A 234 Grade WP11, WP12
1.7380 10 CrMo 9 1010CrMo9-10A 234 Grade WP22
1.7362 12 CrMo 19 5X11CrMo5A 234 Grade WP5
– –A 234 Grade WP9
1.4903  –X10CrMoVNb9-1A 234 Grade WP91
LOW-TEMPERATURE CARBON STEEL FITTINGS MATERIALS
1.5637 10 Ni 1412Ni14A 420 Grade WPL3
1.0356 TTSt 35 NP215NL (1.0451)
1.0356 TTSt 35 V
– –A 420 Grade WPL6
HIGH-YIELD CARBON STEEL FITTINGS MATERIALS
– –
1.0486 StE 285A860 Grade WPHY42
1.0562 StE 355P355NA860 Grade WPHY52
1.8902 StE 420A860 Grade WPHY60
1.8905 StE 460A860 Grade WPHY70
HIGH-YIELD CARBON STEEL FITTINGS MATERIALS
1.0457 StE 240.7
1.0484 StE 290.7L290NBA860 Grade WPHY42
1.0582 StE 360.7L360NBA860 Grade WPHY52
1.8972 StE 415.7L415NBA860 Grade WPHY60
– –
STAINLESS STEEL FITTINGS MATERIALS
1.4541 X 6 CrNiTi 18 10X6CrNiTi18-10A 403 Grade WP321
1.4571 X 6 CrNiMoTi 17 12 2X6CrNiMoTi17-12-2A 403 Grade WP316Ti
1.4301 X 5 CrNi 18 10X5CrNi18-10A 403 Grade WP304
1.4306 X 2 CrNi 19 11X2CrNi19-11A 403 Grade WP304L
1.4307  –X2CrNi18-9A 403 Grade WP304L
1.4401 X 5 CrNiMo 17 12 2X5CrNiMo17-12-2A 403 Grade WP316
1.4404 X 2 CrNiMo 17 13 2X2CrNiMo17-12-2A 403 Grade WP316L
1.4462 X 2 CrNiMoN 22 5 3X2CrNiMoN22-5-3UNS S 31803 (Duplex)
1.4529 X 1 NiCrMoCuN 25 20 6X1NiCrMoCuN25-20-7UNS N 08926
1.4539 X 1 NiCrMoCuN 25 20 5X1NiCrMoCu25-20-5UNS N 08904 (904L)
1.4547  –X1CrNiMoCuN20-18-7UNS S 31254

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About the Author

Projectmaterials Team

Projectmaterials Team

Blog.projectmaterials.com is an online resource dedicated to providing in-depth information, analysis, and educational content related to the fields of project materials management, engineering, and procurement, particularly within the oil & gas, construction, shipbuilding, energy, and renewable energy sectors. It aims to serve professionals and enthusiasts in these industries by offering valuable insights into materials, equipment, and techniques used in various projects, focusing on the selection, application, and maintenance of these resources.Key features of the blog include:* Educational Articles: Comprehensive posts that cover topics ranging from the technical aspects of piping products (pipes, valves, fittings, flanges, gaskets, bolts, instrumentation) to structural steel and process equipment (including oil extraction systems, drilling rigs, wellheads, pumps, compressors, and separation systems). * Industry Insights: Updates on the latest trends, technologies, and regulatory changes affecting the industries covered. * Guides and How-Tos: Practical advice on selecting the right materials and equipment for specific applications, as well as tips on installation, maintenance, and troubleshooting. * Safety and Standards: Information on safety equipment for production sites, risk mitigation procedures, and an overview of relevant industry standards and regulatory frameworks.The website is designed to support the professional development of engineers, procurement specialists, project managers, and other stakeholders involved in project plant businesses, by disseminating critical know-how and best practices. Whether readers are new to the field or seasoned professionals, blog.projectmaterials.com offers resources to enhance their understanding and performance in managing project materials effectively.

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3 Responses

  1. we would like to thank you for such a good blog on different grade fittings
    we deep steel alloys are stockist of Inconel 600 Fittings in grades of inconel 625, inconel 825, inconel 600, inconel 800, inconel 718 along with stockist and supplier of inconel, monel, hastelloy, titanium, high nickel alloy in form of flanges, pipe, plate,rod,coil,wire,round bar .
    please mail us – [email protected]

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