IBR Approved · Carbon Steel
ASTM A234 WPB Buttweld Pipe Fittings
The standard carbon steel grade for buttweld fittings — elbows, tees, reducers and caps to ASME B16.9 / B16.28, 1/2" to 48" NB, SCH 20 to XXS. IBR approved with Form IV (Part D) (formerly Form III-C), EN 10204 3.1 / 3.2 traceable.
Where WPB Is Used
- ✓ General process, utility, water and steam piping
- ✓ Boiler feedwater and steam lines under IBR
- ✓ Oil, gas and refinery piping at ambient and moderate temperatures
WPB Compared With Related Grades
| Grade | Service | Key difference |
|---|---|---|
| A234 WPB | General service | The standard carbon steel fitting grade; WPB-W for welded construction |
| A234 WPC | Higher strength | 485–655 MPa tensile, used where WPB strength is not enough |
| A420 WPL6 | Low temperature | Charpy impact tested at −46 °C |
| A234 WP11 | Elevated temperature | Chrome-moly alloy for creep resistance |
How to Specify WPB Fittings on a Purchase Order
A complete order line avoids clarification rounds. Example:
Reducer concentric, 6" × 4" SCH 40, ASTM A234 WPB, ASME B16.9, EN 10204 3.1
- ✓ State seamless (WPB) or welded (WPB-W) if your specification restricts it
- ✓ Add NACE MR0175 / ISO 15156 hardness for sour service
- ✓ Add IBR Form IV (Part D) if the line is under the Indian Boiler Regulations
Grade Overview
ASTM / ASME A234 WPB is the workhorse carbon steel grade for wrought buttweld pipe fittings. It covers seamless and welded fittings for moderate-temperature service in refineries, power plants, boiler auxiliaries and general process and utility piping. Fittings are formed from A106 / A53 seamless or EFW pipe and normalised where required to meet the mechanical and toughness requirements of the specification.
For boiler and steam service under the Indian Boiler Regulations, WPB fittings are supplied IBR approved with Form IV (Part D) certification, within the pressure and temperature limits applicable to carbon steel.
Chemical Composition — A234 WPB
| Element | Requirement | Note |
|---|---|---|
| Carbon (C) | ≤ 0.30% | Weldability / strength balance |
| Manganese (Mn) | 0.29 – 1.06% | Strength & deoxidation |
| Silicon (Si) | ≥ 0.10% | Deoxidiser |
| Phosphorus (P) | ≤ 0.050% | Impurity limit |
| Sulphur (S) | ≤ 0.058% | Impurity limit |
| Cr, Cu, Mo, Ni, V | Residual limits | Cr/Cu/Ni ≤0.40, Mo ≤0.15, V ≤0.08 (sum limit applies) |
Mechanical Properties — A234 WPB
| Property | Requirement |
|---|---|
| Tensile Strength | 415 – 585 MPa (60 – 85 ksi) |
| Yield Strength (min) | 240 MPa (35 ksi) |
| Elongation (min) | ≥ 22% (longitudinal, per specification formula) |
| Heat Treatment | As-formed / normalised as required by forming method |
Equivalent Grades
| Product Form | Specification |
|---|---|
| Buttweld fittings | ASTM / ASME A234 WPB |
| Seamless pipe | ASTM A106 Gr. B |
| Forgings / flanges | ASTM A105 |
| Welded / seamless pipe | ASTM A53 Gr. B |
EN 10253 equivalent: see WPB pipe fittings on arshyapipefittings.com, and the closest European grade EN 1.0345 (P235GH).
Fitting Types Available in WPB
- Elbows — 45° / 90° / 180°, LR & SR (B16.9 / B16.28)
- Tees — equal & reducing (B16.9)
- Reducers — concentric & eccentric
- Caps — buttweld end closures
- Stub Ends — Type A & B for lap joints
- Laterals & Crosses — branch connections
Related grades: WPL6 · WP11 · WP22 · Flanges · IBR Form IV (Part D) guide · IBR grades list
Testing & Inspection — WPB
- Chemical analysis of each heat, including carbon-equivalent control for weldability.
- Tensile and hardness tests to ASTM A234 (415–585 MPa tensile, 240 MPa min. yield).
- Weld radiography for welded (WPB-W) fittings, as ASTM A234 requires for “W” fittings.
- Dimensional and visual inspection to ASME B16.9; additional NDE, hardness limits for sour service (e.g. NACE MR0175) or impact tests on request.
Dimensions & Size Range — ASME B16.9
WPB fittings are made to ASME B16.9 (long-radius) and ASME B16.28 (short-radius elbows) dimensions, from 1/2" to 48" NB and above, in schedules SCH 20 to SCH 160 / XXS. Wall thickness matches the connecting pipe schedule. Centre-to-end dimensions for the most-ordered sizes:
| NPS | Outside diameter (mm) | 90° LR elbow “A” (mm) | 45° LR elbow “B” (mm) | Equal tee “C” (mm) |
|---|---|---|---|---|
| 1/2" | 21.3 | 38 | 16 | 25 |
| 1" | 33.4 | 38 | 22 | 38 |
| 2" | 60.3 | 76 | 35 | 64 |
| 3" | 88.9 | 114 | 51 | 86 |
| 4" | 114.3 | 152 | 64 | 105 |
| 6" | 168.3 | 229 | 95 | 143 |
| 8" | 219.1 | 305 | 127 | 178 |
| 10" | 273.1 | 381 | 159 | 216 |
| 12" | 323.9 | 457 | 190 | 254 |
| 16" | 406.4 | 610 | 254 | 305 |
| 20" | 508.0 | 762 | 318 | 381 |
| 24" | 610.0 | 914 | 381 | 432 |
Long-radius elbows have a centre-line radius of 1.5 × NPS; short-radius (ASME B16.28) 1.0 × NPS. Full tables to NPS 48, reducing tees, reducers and caps are available with every quotation. For EN 10253 dimensions see arshyapipefittings.com.
Export Documentation & Packing
We ship WPB fittings to projects outside India with the documents EPC contractors and inspection agencies expect:
- Mill test certificate — EN 10204 3.1 as standard; 3.2 with third-party witness
- Third-party inspection — Bureau Veritas, TÜV, Lloyd’s Register, SGS, DNV or the client’s own inspector
- IBR Form IV (Part D) — for boiler piping on Indian Boiler Regulations projects
- Traceability — every fitting marked with grade, size, schedule and heat number, matching the certificate
- Packing — seaworthy wooden cases or pallets, bevel ends protected with end caps
- Shipping documents — commercial invoice, packing list and certificate of origin; FOB, CFR or CIF terms
Send your BOQ through the RFQ form (Excel or PDF attachments accepted) or on WhatsApp — quotations are usually issued within 24 hours.
WPB Fittings — Frequently Asked Questions
What is the difference between WPB and WPC?
Both are carbon steel under ASTM A234. WPC has higher strength (485–655 MPa tensile, 275 MPa min. yield) against WPB’s 415–585 MPa and 240 MPa. WPB is by far the more common grade.
What does WPB-W mean?
“W” marks a welded fitting — made from welded pipe or plate rather than seamless — whose welds are radiographed as ASTM A234 requires. Seamless WPB fittings carry no suffix.
Can WPB be used below −29°C?
No — WPB is not impact tested. For low-temperature service down to −46°C specify ASTM A420 WPL6.