Description
Factory-made butt-welding pipe fitting
ASTM A234 WPB Carbon Steel Butt Weld Cap
A robust, economical factory-made closure for carbon steel process piping, supplied with the wall thickness, bevel and documentation required by the project.
What is an ASTM A234 WPB butt weld cap?
An ASTM A234 WPB butt weld cap is a wrought carbon steel fitting used to permanently close a pipe, manifold or header. The cap is formed to a rounded closed profile and welded directly to the matching pipe, eliminating a gasketed joint and minimizing installed envelope.
WPB is a widely used carbon steel fitting grade for moderate- and elevated-temperature service. It is commonly paired with compatible carbon steel piping in oil and gas, power, steam and industrial utilities. Low-temperature service with project impact requirements may instead call for ASTM A420 WPL6.
A234 WPB butt weld cap specifications
| Product type | Carbon steel butt weld pipe cap / BW end cap |
|---|---|
| Material specification | ASTM A234 WPB |
| Dimensional standard | ASME B16.9 |
| Nominal size | NPS 1/2–48 / DN15–DN1200, subject to wall and manufacturing route |
| Wall thickness | Sch 20, 30, STD, 40, 60, XS, 80, 100, 120, 140, 160, XXS and custom wall |
| Construction | Seamless or welded as applicable and ordered |
| End preparation | Butt-weld bevel to the ordered pipe wall and welding detail |
| Surface protection | Bare, anti-rust oil, black paint or project-specific coating |
| Testing options | Dimensional inspection, MT, UT, RT, hardness or third-party inspection as specified |
| Documentation | EN 10204 3.1 MTC, heat traceability and inspection records as ordered |
Dimensions and tolerances follow the ordered standard and edition. Final pressure-temperature suitability is determined by the piping design code, material, wall thickness, matching pipe and service conditions.
ASME and European project requirements
North American projects
Specify ASTM A234 WPB, ASME B16.9, NPS, schedule, construction, end preparation, surface protection and supplementary testing. State any sour-service or project chemistry restrictions separately.
European projects
For EN-based projects, specify the required EN steel grade and product standard rather than assuming direct equivalence with WPB. Include DN, wall, fitting dimensions, coating and EN 10204 certificate type.
A234 WPB vs A420 WPL6 pipe cap
| Selection point | ASTM A234 WPB | ASTM A420 WPL6 |
|---|---|---|
| Primary service family | Moderate- and elevated-temperature carbon steel piping | Low-temperature carbon steel piping |
| Impact requirements | As required by design code and project specification | Low-temperature impact testing is a defining procurement consideration |
| Typical use | Oil, gas, steam, power and utilities | Cold-climate, refrigerated and low-temperature process systems |
| Selection rule | Use when the design specification calls for A234 WPB | Use only with the ordered WPL6 heat treatment and impact criteria |
Typical applications
| Industry | Typical service | Selection reason |
|---|---|---|
| Oil and gas | Process headers, gathering lines and equipment branches | Common carbon steel fitting grade and broad availability |
| Power generation | Steam, condensate and plant utility terminations | Robust butt-welded construction |
| Petrochemical | Hydrocarbon and general process piping | Schedule range and project inspection options |
| Industrial utilities | Water, compressed air and non-corrosive services | Economical permanent closure |
Application examples are guidance only. The project engineer must confirm material compatibility, corrosion allowance, impact requirements and design-code compliance.
Manufacturing, inspection and documentation
Manufacturing may include cutting, forming, heat treatment as required, calibration, bevel machining, surface preparation and inspection. The purchase order should state construction, supplementary testing, impact requirements if any and coating system.
Heat-number control and MTC review against the purchase specification.
Outside diameter, overall length, wall thickness, ovality and bevel geometry checked as ordered.
PT, MT, UT, RT, hardness or third-party inspection can be arranged when specified.
EN 10204 3.1 certificate and inspection records supplied according to the purchase order.
RFQ checklist
- Material grade and product specification
- Dimensional standard and edition
- NPS or DN size
- Pipe schedule or exact wall thickness
- Seamless or welded construction, when required
- End preparation and bevel detail
- Quantity and delivery destination
- MTC, NDE and third-party inspection requirements
Frequently asked questions
What does ASTM A234 WPB cover?
ASTM A234 WPB is a carbon steel fitting grade used for wrought fittings in moderate- and elevated-temperature piping applications. ASME B16.9 supplies the fitting dimensions and tolerances.
Is WPB suitable for low-temperature service?
Do not assume so from the grade name. Low-temperature piping with specified impact toughness commonly uses ASTM A420 WPL6 or another material selected by the project engineer.
Can the cap match Sch 160 or XXS pipe?
Heavy-wall caps can be supplied in many sizes, but manufacturability depends on outside diameter, exact wall, construction route and quantity. Provide the pipe dimensions for review.
Which coatings are available?
Bare finish, anti-rust oil, black paint and project-specific coating systems are common options. Coating compatibility and weld-area requirements should be specified.
Can NDE be arranged?
Yes. MT, UT, RT, hardness testing and third-party inspection can be arranged when the method, extent and acceptance criteria are stated in the order.
Request an A234 WPB butt weld cap quotation
Send the NPS, schedule, quantity, surface protection and inspection requirements for a fast technical and commercial offer.
