ASTM A234 WPB butt weld elbows are the workhorse pipe fitting of carbon steel piping systems: 90° and 45° direction changes in seamless and ERW pipe runs, made from ASTM A106-grade pipe and heat treated to the A234 specification. “WPB” means Wrought Pipe, Grade B — the fitting counterpart to A106 Grade B and A333 Gr6 piping. Huaxia-Steel supplies A234 WPB elbows from 1/2″ to 48″ in Sch 40 through Sch 160, seamless and welded, with beveled ends ready for welding and full EN 10204 3.1 certification.
Product Overview
ASTM A234/A234M covers wrought carbon steel and alloy steel fittings of seamless and welded construction for moderate and high-temperature service. The WPB grade is made from pipe or plate of compatible chemistry (max 0.30 % C, 0.29–1.06 % Mn), formed by hot induction bending, hot pressing or forging, then heat treated — normally normalized at 870–980 °C or quenched and tempered for thicker walls. Every fitting is marked with the manufacturer’s mark, material grade, size, schedule and heat number per MSS SP-25.
Elbows are supplied in 90° long radius (LR, radius = 1.5×NPS), 90° short radius (SR, radius = 1.0×NPS), and 45° LR versions. LR elbows are the default for process piping because their gentler radius cuts pressure drop and erosion roughly in half compared with SR; SR elbows exist for tight layouts such as compressor skids and ship piping where space dominates.
Specifications and Dimensions
| Item | Specification |
|---|---|
| Standard | ASTM A234/A234M Grade WPB |
| Size range | NPS 1/2 – NPS 48 (DN 15 – DN 1200) |
| Wall | Sch 10 – Sch 160, STD, XS, XXS |
| Type | Seamless (≤ 24″), welded (up to 48″) |
| Angles / radius | 90° LR, 90° SR, 45° LR; 3D and 5D bends on request |
| Ends | Butt weld beveled to ASME B16.25 (37.5° + root face) |
| Dimensions | ASME B16.9 (factory-made wrought fittings); B16.28 for ≤ NPS 24 small bore above Sch XXS |
| Coating | Black paint, varnish, FBE, 3LPE on request |
Chemical and Mechanical Requirements
| Property | WPB requirement |
|---|---|
| Carbon max | 0.30 % |
| Manganese | 0.29 – 1.06 % |
| P / S max | 0.050 % / 0.058 % (product analysis 0.058 S) |
| Tensile strength min | 415 MPa (60 ksi) |
| Yield strength min | 240 MPa (35 ksi) |
| Heat treatment | Normalized (870–980 °C) or Q+T; annealed by agreement |
| Hardness | No max specified (typical ≤ 187 HB) |
Related Fitting Grades in the A234 Family
| Grade | Base material | Use with | Notes |
|---|---|---|---|
| WPB | Carbon steel | A106 Gr B / A53 Gr B pipe | Standard grade, −29 to +425 °C typical |
| WPL6 | Fine grain low temp carbon | A333 Gr 6 pipe | Charpy tested to −45 °C (per ASTM A420) |
| WPC | Higher carbon | A106 Gr C | Higher strength class |
| WP11 / WP12 | 1.25Cr-0.5Mo / 0.5Cr-0.5Mo | A335 P11/P12 | High temperature boiler service |
| WP22 / WP91 | 2.25Cr-1Mo / 9Cr-1Mo-V | A335 P22/P91 | Power plant main steam |
Manufacturing Process and Quality Assurance
Seamless elbows start from cut pipe lengths (or plate for welded bodies), are hot formed on hydraulic presses or induction benders, then heat treated and machined on the bevel. Testing per A234 includes: tensile test per heat/lot, hardness survey, visual and dimensional check to B16.9 tolerances (including wall thickness at the extrados, the thinning-critical zone), and surface NDT — MT or PT on heat treated lots. Non-destructive examination is required when specified; for critical service order 100 % UT plus RT of the weld seam on welded-body fittings.
Certification: EN 10204 3.1 with heat-level chemistry and mechanical results is standard; 3.2 with third-party witness (SGS/BV/TÜV) available. Marking per MSS SP-25 is stamped or inked: manufacturer, WPB, NPS, schedule, heat number and — where applicable — the “P” grade designator.
Typical Applications
- Oil and gas process piping (wellhead flowlines, manifolds, gas plants).
- Petrochemical and refinery units (fractionation, hydrotreaters, utilities).
- Power plant feedwater and steam lines to 425 °C.
- Water transmission, firewater and firefighting networks.
- Shipbuilding and offshore platform process systems.
- HVAC and compressed air headers in industrial plants.
Packing and Shipping
Fittings are packed in plywood cases or steel pallets with bevel protectors (plastic caps or tape rings), each piece tagged with grade/size/schedule/heat. Cases carry seaworthy wrapping; FBE and 3LPE coated fittings ship with padded separators to protect the coating. Container loads are limited to bevel-protected small bores; large diameter elbows move on flat racks or breakbulk with load plans per the CTU code.
Elbow Dimensions and Weight Reference
| NPS | OD mm | LR 90° center-to-face mm | Sch 40 weight kg/pc | Sch 80 weight kg/pc |
|---|---|---|---|---|
| 2″ | 60.3 | 76 | 1.1 | 1.5 |
| 4″ | 114.3 | 152 | 4.3 | 6.2 |
| 6″ | 168.3 | 229 | 9.5 | 14.4 |
| 8″ | 219.1 | 305 | 17.9 | 27.7 |
| 12″ | 323.9 | 457 | 43.2 | 71.7 |
| 16″ | 406.4 | 610 | 76.9 | 131.1 |
| 24″ | 610.0 | 914 | 186.7 | 328.4 |
45° LR elbows weigh approximately 60 % of the 90° values; SR 90° elbows approximately 70 %. Weights are theoretical per ASME B16.9 and vary with actual wall in the extrados zone.
Coating and Surface Protection Options
- Black varnish / paint: standard mill finish for carbon steel, prevents flash rust during transit.
- Shot blasted Sa2.5 + shop primer: ready for site coating, 15–25 µm.
- FBE (fusion bonded epoxy): 300–500 µm, standard for buried and submerged pipelines.
- 3LPE / 3LPP: three-layer polyethylene/polypropylene for long-distance pipelines, applied after bevel masking.
- Hot dip galvanized: for utility and firewater systems, per ASTM A153.
How to Order
For a fast, accurate quotation, provide: size (NPS), schedule or wall thickness, angle (90°/45°), radius (LR/SR), type (seamless or welded), end bevel standard, coating, quantity, certificate level (3.1/3.2) and destination port. If your project follows a piping class, send the class page — we will match material, heat treatment and NDT requirements including any supplementary testing such as impact tests for low temperature service.
Frequently Asked Questions
What is the difference between WPB and WPL6 elbows?
WPB is the standard carbon grade with no low-temperature impact requirement; WPL6 (per ASTM A420) is the fine-grain grade Charpy-tested at −45 °C to pair with A333 Gr6 pipe. For ambient service they are interchangeable in strength; for cold service, only WPL6 is valid.
Why is the wall thinner at the back of the elbow?
Hot forming stretches the extrados (outer radius), thinning it by up to 12.5 %, while the intrados thickens. ASME B16.9 accounts for this: the fitting is designed so the finished elbow matches the pressure rating of the connecting pipe even at the thinned extrados. Verify wall thickness measurements are taken at the extrados when inspecting.
Can I order elbows in 3D or 5D radius?
Yes — long sweep bends (3D, 5D, 6D) are induction bent from pipe and supplied as bends rather than standard B16.9 elbows. They reduce erosion and pressure drop in slurry and high-velocity gas service; lead time and price are higher because each bend is made to order.
Documentation and Traceability
Every fitting ships with EN 10204 3.1 certificates tying the heat number stamped on each piece to its chemistry and mechanical tests, plus dimensional reports against ASME B16.9 and the marking layout per MSS SP-25. Case-level packing lists list piece counts, weights and heat numbers, and container loads include the loading photo set. This traceability chain — heat to fitting to case to container — is what plant QC teams need for code-stamped construction, and it is standard on every Huaxia-Steel order, not an upgrade.
Request a Quote
Send us your elbow list (size, schedule, angle, radius), quantity and destination — Huaxia-Steel replies with a factory-direct quotation and MTC samples within 24 hours. Matching tees, reducers, caps and A420 WPL6 fittings available from the same production line.
