A complete overview of ASTM materials for buttweld fittings: ASTM A234 (carbon and low-alloy steel), ASTM A403 (stainless steel), ASTM A815 (duplex and super duplex), and ASTM B366 (nickel alloys). The article reviews the chemical and mechanical properties of these pipe fittings specifications and their common uses.
BUTTWELD FITTINGS MATERIALS
Carbon steel buttweld fittings are common for pipelines and process piping in the oil and gas and power generation industry, stainless steel fittings are for higher temperature, pressure and corrosion applications (desalination, pharmaceutical and, food sectors).
Let’s dive into the three main groups of materials for buttweld fittings, ASTM A234 (carbon/alloy pipe fittings), ASTM A403 (stainless steel), and ASTM A815 (duplex and super duplex BW pipe fittings).
Important to note that the material of the pipe and the buttweld fitting shall match (for example, an ASTM A106 Gr. B pipe shall be connected to an ASTM A234 WPB BW fitting, or an ASTM A312 T304 pipe has to be welded to an ASTM A403 WP304 fitting and so on). It is not possible to use pipes and buttweld fittings of different materials. Likewise, the size of the buttweld fitting and the size of the connected pipe shall match.
The fittings materials compatible with specific pipes are shown in the piping materials match table.
CARBON/ALLOY STEEL BUTTWELD FITTINGS (ASTM A234)
The ASTM A234 specification covers carbon steel and alloy steel pipe fittings (butt weld) for high-temperature service.
A234 WPA, WPC and, WPC fittings match ASTM A53, ASTM A106 and, API 5L Gr. B pipes. A234 WP1 to WP91 butt weld fittings match ASTM A335 chrome-moly pipes.
The ASTM A420 specification covers low-temperature carbon steel butt weld fittings to match ASTM A333 Gr.3 and ASTM A333 Gr. 6 pipes; the 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.
ASTM A234 Chemical Composition
Chemical composition of ASTM A234 Carbon and Alloy Steel Fittings
Grade
C
Mn
P max
S max
Si
Cr
Mo
Ni
Cu
Others
WPB
(1,2,3,4,5)
0.30
max
0.29-1.06
0.050
0.058
0.10
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
0.29-1.06
0.050
0.058
0.10
min
0.40
max
0.15
max
0.40
max
0.40
max
V 0.08
max
WP1
0.28
max
0.30-0.90
0.045
0.045
0.10-0.50
0.44-0.65
WP12 CL1
0.05-
0.20
0.30-0.80
0.045
0.045
0.60
max
0.80-1.25
0.44-0.65
WP12 CL2
0.05-
0.20
0.30-0.80
0.045
0.045
0.60
max
0.80-1.25
0.44-0.65
WP11 CL1
0.05-
0.15
0.30-0.60
0.030
0.030
0.50-1.00
1.00-1.50
0.44-0.65
WP11 CL2
0.05-
0.20
0.30-0.80
0.040
0.040
0.50-1.00
1.00-1.50
0.44-0.65
WP11 CL3
0.05-
0.20
0.30-0.80
0.040
0.040
0.50-1.00
1.00-1.50
0.44-0.65
WP22 CL1
0.05-
0.15
0.30-0.60
0.040
0.040
0.50
max
1.90-2.60
0.87-1.13
WP22 CL3
0.05-
0.15
0.30-0.60
0.040
0.040
0.50
max
1.90-2.60
0.87-1.13
WP5 CL1
0.15
max
0.30-0.60
0.040
0.030
0.50
max
4.0-6.0
0.44-0.65
WP5 CL3
0.15
max
0.30-0.60
0.040
0.030
0.50
max
4.0-6.0
0.44-0.65
WP9 CL1
0.15
max
0.30-0.60
0.030
0.030
1.00
max
8.0-10.0
0.90-1.10
WP9 CL3
0.15
max
0.30-0.60
0.030
0.030
1.00
max
8.0-10.0
0.90-1.10
WPR
0.20
max
0.40-1.06
0.045
0.050
1.60-
2.24
0.75-1.25
WP91
0.08-
0.12
0.30-0.60
0.020
0.010
0.20-0.50
8.0-9.5
0.85-1.05
0.40
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)
WP911
0.09-
0.13
0.30-0.60
0.020
0.010
0.10-0.50
8.0-9.5
0.90-1.10
0.40
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:
Fittings from bar or plate 0.35 max carbon.
Fittings from forgings 0.35 max Carbon and 0.35 max Silicon with no minimum.
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%.
The sum of Cu, Ni, Niobium, and Moly shall not exceed 1.00%.
The sum of Niobium and Moly shall not exceed 0.32%.
Applies to heat and product analyses
ASTM A234 Mechanical Properties
Tensile and Yield Strength ASTM A234 for Carbon and Alloy Steel Fittings
WPB
WPC,
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 Fittings
WPB,
WPC, WP11, WP22
WP91
Longitud.
Transverse
Longitud.
Transverse
Standard
round specimen, or small proportional specimen, min % in 4 D
22
14
20
13
Rectangular specimen for wall thickness 5/16″ and over, and
for all small sizes tested in full section; min % in 2 in.
30
20
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 are permitted
STAINLESS STEEL BUTTWELD FITTINGS (ASTM A403)
The ASTM A403 specification covers austenitic stainless steel butt weld fittings to match ASTM A312 TP304, TP316, TP321, etc., pipes.
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-
7.00.030.01116.0-18.023.0-25.04.0-5.00.40-0.60Nb 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-
6.513.0-17.013.0-15.00.75-1.50Cu 0.75-1.50Al 0.30
Notes:
- Maximum, if not otherwise indicated.
- The method of analysis for Nitrogen is agreed between the purchaser and manufacturer.
- Niobium 0.10-0.30%; Vanadium, 0.10-0.30%.
- 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.
- On pierced tubing, the Nickel maybe 11.0-16.0%.
- 5 X (C+N2)-0.70.
- 4 X (C+N2) -0.70.
- The Niobium % shall be ten times above the Carbon content and not more than 1.10%.
- 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 A403
WP304, WP316
WP304L, WP316L
Yield Strength, min, ksi [MPa]
30 [205]
25 [170]
Tensile Strength, min, ksi [MPa]
75 [515]
70 [485]
Elongation
Longitudinal
28
28
Transverse
20
20
DUPLEX/ SUPER DUPLEX BUTTWELD FITTINGS (ASTM A815)
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, flue gas desulfurization processes.
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)
Grade
C
Mn
Si
P
S
Cr
Mo
Ni
N
Fe
S31803
0.030 max
2.00 max
1.00 max
0.030 max
0.020 max
22.0 – 23.0
3.0 – 3.5
4.50 – 6.50
0.14 – 0.20
63.72 min
S32205
0.030 max
2.00 max
1.00 max
0.030 max
0.020 max
21.0 – 23.0
2.50 – 3.50
4.50 – 6.50
0.8 – 0.20
63.54 min
UNS S31803, UNS S32205 Mechanical Properties (Duplex)
Grades
Density (g/cm 3)
Density (lb/in 3)
Melting Point (°C)
Melting Point (°F)
S31803 / S32205
7.805
0.285
1420 – 1465
2588 – 2669
UNS S32750, UNS S32760 Chemical Composition (Super Duplex)
Grade
C
Mn
Si
P
S
Cr
Mo
Ni
N
Fe
S 32750
0.030 max
1.20 max
0.80 max
0.035 max
0.020 max
24.00 – 26.00
3.00 – 5.00
6.00 – 8.00
0.24 – 0.32
58.095 min
S 32760
0.05 max
1.00 max
1.00 max
0.030 max
0.010 max
24.00 – 26.00
3.00 – 4.00
6.00 – 8.00
0.20 – 0.30
57.61 min
UNS S32750, UNS S32760 Mechanical Properties (Super Duplex)
Grades
Density (g/cm 3)
Density (lb/in 3)
Melting Point (°C)
Melting Point (°F)
S32750 / S32760
7.8
0.281
1350
2460
NICKEL ALLOY BUTTWELD FITTINGS (ASTM B366)
Nickel alloy buttweld fittings are used for higher pressure/temperature and corrosive media, where lower grades would fail. The ASTM B366/SB 366 specification covers these high-alloy grades buttweld fittings (super-alloys) as Inconel, Incoloy, Hastelloy 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
Name
UNS
DIN
Matching Pipe Grade
Equivalent Forged Grade
904L
N08904
1.4539
B677/B673
B649
Alloy 020
N08020
2.466
B729/B464
B462
Alloy 230
N06230
–
B622/B619
B564
Alloy 400 (Monel)
N04400
2.436
B165/B725
B564
Alloy 59
N06059
2.4605
B622/B619
B564
Alloy 600 (Inconel)
N06600
2.4816
B167/B517
B564
Alloy 625 (Inconel)
N06625
2.4856
B444/B705
B564
Alloy 800 (Incoloy)
N08800
1.4558
B407/B514
B564
Alloy 800H (Incoloy)
N08810
1.4958
B407/B514
B564
Alloy 800HT (Incoloy)
N08811
1.4959
B407
B564
Alloy 825 (Incoloy)
N08825
2.4858
B423/B705
B564
Alloy B
N10001
–
B622/B619
–
Alloy B2 (Hastelloy)
N10665
2.4617
B622/B619
–
Alloy B3 (Hastelloy)
N10675
–
B622/B619
B564
Alloy C22 (Hastelloy)
N06022
2.4602
B622/B619
B564
Alloy C276 (Hastelloy)
N10276
2.4819
B622/B619
B564
Alloy C4
N06455
2.461
B622/B619
–
Alloy G-3
N06985
2.4619
B622/B619
–
Alloy G30
N06030
–
B622/B619
–
Alloy K500 (Monel)
N05500
2.4375
–
B865
Nickel 200
N02200
2.4066
B161/B725
B564
Nickel 201
N02201
2.4068
B161/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 Alloy
Typical 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 exposed to corrosive attack from 1100-1800° F
- Industrial furnaces
- Heat-treating equipment
- Chemical and petrochemical processing
- Super-heater 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 FITTINGS
In some cases, buttweld fittings can be externally coated with protective materials, internally lined (example PTFE may be inserted to enhance the resistance of the bare metal to corrosive fluids) or clad (the picture shows a clad tee: the tee is made of carbon steel, but the inner side is covered by a higher grade material, stainless steel 316 in this case).
EUROPEAN VS ASTM BUTTWELD FITTINGS MATERIALS
The table shows the equivalent ASTM and European pipe fittings materials grades.
Butt Weld Fittings Materials Comparison Chart
Werkstoff Number
European Grade
ASTM Grade
CARBON STEEL FITTINGS MATERIALS
1.0254 St 37.0
S235
–
– –
–
–
1.0305 St 35.8/I
P235GH (1.0345)
A 234 Grade WPA
1.0305 St 35.8/III
P235GH (1.0345)
–
1.0405 St 45.8/I
P265GH (1.0425)
A 234 Grade WPB
1.0405 St 45.8/III
P265GH (1.0425)
–
ALLOY STEEL FITTINGS MATERIALS
1.5415 15 Mo 3
16Mo3
A 234 Grade WP1
1.7335 13 CrMo 4 4
13CrMo4-5
A 234 Grade WP11, WP12
1.7380 10 CrMo 9 10
10CrMo9-10
A 234 Grade WP22
1.7362 12 CrMo 19 5
X11CrMo5
A 234 Grade WP5
– –
–
A 234 Grade WP9
1.4903 –
X10CrMoVNb9-1
A 234 Grade WP91
LOW-TEMPERATURE CARBON STEEL FITTINGS MATERIALS
1.5637 10 Ni 14
12Ni14
A 420 Grade WPL3
1.0356 TTSt 35 N
P215NL (1.0451)
–
1.0356 TTSt 35 V
–
–
– –
–
A 420 Grade WPL6
HIGH YIELD CARBON STEEL FITTINGS MATERIALS
– –
–
–
1.0486 StE 285
–
A860 Grade WPHY42
1.0562 StE 355
P355N
A860 Grade WPHY52
1.8902 StE 420
–
A860 Grade WPHY60
1.8905 StE 460
–
A860 Grade WPHY70
HIGH YIELD CARBON STEEL FITTINGS MATERIALS
1.0457 StE 240.7
–
–
1.0484 StE 290.7
L290NB
A860 Grade WPHY42
1.0582 StE 360.7
L360NB
A860 Grade WPHY52
1.8972 StE 415.7
L415NB
A860 Grade WPHY60
– –
–
–
STAINLESS STEEL FITTINGS MATERIALS
1.4541 X 6 CrNiTi 18 10
X6CrNiTi18-10
A 403 Grade WP321
1.4571 X 6 CrNiMoTi 17 12 2
X6CrNiMoTi17-12-2
A 403 Grade WP316Ti
1.4301 X 5 CrNi 18 10
X5CrNi18-10
A 403 Grade WP304
1.4306 X 2 CrNi 19 11
X2CrNi19-11
A 403 Grade WP304L
1.4307 –
X2CrNi18-9
A 403 Grade WP304L
1.4401 X 5 CrNiMo 17 12 2
X5CrNiMo17-12-2
A 403 Grade WP316
1.4404 X 2 CrNiMo 17 13 2
X2CrNiMo17-12-2
A 403 Grade WP316L
1.4462 X 2 CrNiMoN 22 5 3
X2CrNiMoN22-5-3
UNS S 31803 (Duplex)
1.4529 X 1 NiCrMoCuN 25 20 6
X1NiCrMoCuN25-20-7
UNS N 08926
1.4539 X 1 NiCrMoCuN 25 20 5
X1NiCrMoCu25-20-5
UNS N 08904 (904L)
1.4547 –
X1CrNiMoCuN20-18-7
UNS S 31254