ASTM A234 is a standard specification that covers carbon and alloy steel pipe fittings intended for pressure piping and pressure vessel applications. ASTM A234 standard specifies the chemical composition, mechanical properties, as well as manufacturing and testing requirements for these fittings. ASTM A234 fittings include elbows, tees, reducers, and are commonly used in the oil, gas, and chemical industries to ensure safety and reliability under moderate to high temperature conditions.
Scope of ASTM A234 Specification
ASTM A234 specification covers wrought carbon steel and alloy steel fittings, both seamless and welded, as outlined in the latest revisions of ASME B16.9, B16.11, MSS-SP-79, MSS-SP-83, MSS-SP-95, and MSS-SP-97. These fittings are intended for use in pressure piping and pressure vessel fabrication at moderate and elevated temperatures.
This specification does not cover cast welding fittings or fittings machined from castings.
Referenced Documents
ASME Standards
- B16.9: Steel Butt-Welding Fittings
- B16.11: Forged Steel Fittings, Socket Welding and Threaded
ASME Boiler and Pressure Vessel Code:
- Section V: Nondestructive Examination
- Section VIII, Division 1: Pressure Vessels
- Section IX: Welding Qualifications
MSS Standards
- MSS-SP-25: Standard Marking System for Valves, Fittings, Flanges, and Unions
- MSS-SP-79: Socket Welding Reducer Inserts
- MSS-SP-83: Steel Pipe Unions, Socket-Welding and Threaded
- MSS-SP-95: Swage(d) Nipples and Bull Plugs
- MSS-SP-97: Integrally Reinforced Forged Branch Outlet Fittings—Socket Welding, Threaded and Buttwelding Ends
Chemical Requirements
The material for fittings must consist of killed steel, which may include forgings, bars, plates, sheets, and seamless or fusion-welded tubular products with added filler metal. All materials must meet the chemical requirements outlined in Table. Unless otherwise specified for carbon steel plates and sheets, the steel can be produced using either coarse grain or fine grain practices. However, Grade WP9 must be manufactured using fine grain practices.
Any starting material specification that mandates the addition of elements beyond those specified for the applicable grade in Table 1 is not allowed. This restriction does not prevent the use of deoxidizers or the careful application of elements for controlling grain size.
| Grade and Marking Symbol (A) | Carbon | Manganese | Phosporus | Sulfur | Silicon | Chromium | Molybdenum | Nickel | Copper | Others |
| WPB (B),(C),(D),(E,) | 0.3 | 0.29–1.06 | 0.05 | 0.058 | 0.10 min | 0.4 | 0.15 max | 0.4 | 0.4 | Vanadium 0.08 |
| WPC (C),(D),(E,) | 0.35 | 0.29–1.06 | 0.05 | 0.058 | 0.10 min | 0.4 | 0.15 max | 0.4 | 0.4 | Vanadium 0.08 |
| WP11 CL1 | 0.05–0.15 | 0.30–0.60 | 0.03 | 0.03 | 0.50–1.00 | 1.00–1.50 | 0.44–0.65 | … | … | … |
| WP11 CL2, | 0.05–0.20 | 0.30–0.80 | 0.04 | 0.04 | 0.50–1.00 | 1.00–1.50 | 0.44–0.65 | … | … | … |
| WP11 CL3 | 0.05–0.20 | 0.30–0.80 | 0.04 | 0.04 | 0.50–1.00 | 1.00–1.50 | 0.44–0.65 | … | … | … |
| WP22 CL1, | 0.05–0.15 | 0.30–0.60 | 0.04 | 0.04 | 0.5 | 1.90–2.60 | 0.87–1.13 | … | … | … |
| WP22 CL3 | 0.05–0.15 | 0.30–0.60 | 0.04 | 0.04 | 0.5 | 1.90–2.60 | 0.87–1.13 | … | … | … |
| WP5 CL1, | 0.15 | 0.30–0.60 | 0.04 | 0.03 | 0.5 | 4.0–6.0 | 0.44–0.65 | … | … | … |
| WP5 CL3 | 0.15 | 0.30–0.60 | 0.04 | 0.03 | 0.5 | 4.0–6.0 | 0.44–0.65 | … | … | … |
| WP9 CL1, | 0.15 | 0.30–0.60 | 0.03 | 0.03 | 1 | 8.0–10.0 | 0.90–1.10 | … | … | … |
| WP9 CL3 | 0.15 | 0.30–0.60 | 0.03 | 0.03 | 1 | 8.0–10.0 | 0.90–1.10 | … | … | … |
| WP91 | 0.08–0.12 | 0.30–0.60 | 0.02 | 0.01 | 0.20–0.50 | 8.0–9.5 | 0.85–1.05 | 0.4 | … | Vanadium 0.18–0.25 Columbium 0.06-0.10 Nitrogen 0.03-0.07 Aluminum 0.02(F) Titanium 0.01(F) Zirconium 0.01(F) |
(A) the grade and marking symbol shown above shall be supplemented by letter “W”.
(B) Fittings made from bar or plate may have 0.35 max carbon.A When fittings are of welded construction.
(C) Fittings made from forgings may have 0.35 max carbon and 0.35 max silicon with no minimum.
(D) For each reduction of 0.01 % below the specified carbon maximum, an increase of 0.06 % manganese above the specified maximum will be permitted, up to a maximum of 1.65 %.
(E)The sum of Copper, Nickel, Chromium, and Molybdenum shall not exceed 1.00 %.
(F) Applies both to heat and product analyses.
Mechanical Properties Requirements of Low Temperature Carbon Steel
| 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 | WPB, WPC, WP11, WP22 | WP91 | ||
| Longitundinal | Transverse | Longitundinal | Transverse | |
| Standard round specimen, or small proportioanl specimen, min % in 4 D | 22 | 14 | 20 | 13 |
| Rectangular speicmen for wall thickness 5/16″ and over, and for all small sizes tested in full section; min % in 2 in. | 30 | 20 (A) | ||
| Rectangular speicimen for wall thickness less than 5/16″; min % in 2 in (1/2″ wide specimen) | (B) | (B) | ||
(A) WPB and WPC fittings manufactured from plate shall have a minimum elongation of 17 %.
(B) For each 1⁄32 in. [0.79 mm] decrease in wall thickness below 5⁄16 in. [7.94 mm], a deduction of 1.5 % for longitudinal and 1.0 % for transverse from the values shown above is permitted
Dimensions and Tolerances
Butt-Welding Fittings:
Butt-welding fittings and short radius elbows and returns must conform to the dimensions and tolerances outlined in the latest revision of ASME B16.9.
Socket-Welding and Threaded Fittings:
Steel socket-welding and threaded fittings must meet the sizes, shapes, dimensions, and tolerances specified in the latest revision of ASME B16.11, MSS-SP-79, or MSS-SP-83.
Swaged Nipples and Bull Plugs:
Swage(d) nipples, bull plugs, and integrally reinforced forged branch outlet fittings must conform to the sizes, shapes, dimensions, and tolerances specified in the latest revision of MSS-SP-95 or MSS-SP-97.
Alternate Specifications:
Fittings that differ in size or shape from these standards, but meet all other requirements of this specification, may be provided in accordance with Supplementary Requirement S58 in Specification A960/A960M.
Standards: ANSI /ASME B16.9, B16.28, MSS-SP-43.
Outer Diameter Range: 1/2” to 48”
Thickness Range: SCH 10, sch 20, SCH 40, SCH STD, SCH 80, SCH XS, SCH 160, SCH XXS etc.
Steel pipe fittings manufacturing types in forged, threaded, butt weld, and seamless.
FAQ
This specification covers a variety of fittings, including elbows, tees, reducers, and caps, suitable for welding in high-temperature and moderate-pressure applications.
These fittings are widely used in the oil and gas, chemical processing, power generation, and construction industries.
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