Description
Factory-made butt-welding pipe fitting
ASTM A420 WPL6 Low Temperature Pipe Cap
A butt-welded pipeline closure for low-temperature carbon steel systems, supplied against the ordered impact test, heat treatment and traceability requirements.
What is an ASTM A420 WPL6 low-temperature pipe cap?
An ASTM A420 WPL6 pipe cap is a wrought low-temperature carbon steel fitting used to close the end of a butt-welded pipeline. It is selected when the design specification requires carbon steel fitting toughness at a stated low temperature rather than the general moderate-temperature service associated with ASTM A234 WPB.
WPL6 should not be treated as a generic cryogenic alloy. Allowable design temperature and suitability depend on the ordered heat treatment, impact test temperature and results, wall thickness, piping code and complete service conditions. These requirements must be confirmed before manufacture.
A420 WPL6 low-temperature cap specifications
| Product type | Low-temperature carbon steel butt weld pipe cap |
|---|---|
| Material specification | ASTM A420 WPL6 |
| Dimensional standard | ASME B16.9 |
| Nominal size | NPS 1/2–48 / DN15–DN1200, subject to wall and manufacturing route |
| Wall thickness | Standard schedules, heavy wall, XXS and project-specific wall |
| Construction | Seamless or welded as applicable and ordered |
| Heat treatment | In accordance with ASTM A420 and the ordered project requirements |
| Impact testing | Test temperature, specimen requirements and acceptance criteria must be stated or confirmed from the applicable specification |
| End preparation | Butt-weld bevel to the matching pipe wall and welding detail |
| Documentation | EN 10204 3.1 MTC, heat-treatment and impact-test records, dimensional and NDE reports 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 A420 WPL6, ASME B16.9, NPS, schedule, construction, heat treatment, impact test temperature and acceptance criteria, plus any supplementary NDE or sour-service restrictions.
European projects
Specify the required EN low-temperature steel grade and product standard if the project is EN-based. Include DN, wall, minimum design temperature, impact criteria, regulatory requirements and EN 10204 certificate type.
A420 WPL6 vs A234 WPB pipe cap
| Selection point | ASTM A420 WPL6 | ASTM A234 WPB |
|---|---|---|
| Service focus | Low-temperature carbon steel piping | Moderate- and elevated-temperature carbon steel piping |
| Impact toughness | Ordered low-temperature impact testing is central to material qualification | Project or code impact testing must be considered separately |
| Documentation focus | Heat treatment and impact test records | Chemistry, mechanical properties and general inspection records |
| Typical selection | Refrigerated process, cold climate and low-temperature utilities | Oil, gas, steam, power and general process service |
Typical applications
| Industry | Typical service | Selection reason |
|---|---|---|
| Low-temperature process | Cold hydrocarbon and process utility closures | Specified impact toughness at the ordered temperature |
| Refrigeration | Industrial refrigeration auxiliaries and headers | Low-temperature carbon steel material route |
| Cold-climate facilities | Outdoor process and utility systems | Project-defined toughness and traceability |
| LPG/LNG support systems | Selected non-cryogenic auxiliaries within qualified temperature limits | Carbon steel solution where the design specification explicitly permits WPL6 |
Application examples are guidance only. The project engineer must confirm material compatibility, corrosion allowance, impact requirements and design-code compliance.
Manufacturing, inspection and documentation
WPL6 production and release require careful control of raw material, heat treatment, impact specimens, test temperature and traceability. The manufacturer must receive the complete minimum-design-temperature and acceptance requirements before confirming supply.
Test temperature, specimen orientation, size and absorbed-energy criteria reviewed against the order.
Treatment route and batch traceability linked to the material certificate.
Cap geometry, wall, bevel and specified NDE verified before release.
MTC, impact results, heat treatment and inspection records compiled as ordered.
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 is ASTM A420 WPL6 used for?
It is a low-temperature carbon steel fitting grade used where the piping specification requires verified toughness at a defined low temperature.
What is the minimum service temperature of WPL6?
A single universal service limit should not be assigned without the applicable piping code, heat treatment, wall thickness and ordered impact test data. Confirm the project minimum design metal temperature and acceptance requirements.
Is WPL6 a cryogenic stainless steel?
No. WPL6 is a low-temperature carbon steel fitting grade. True cryogenic services may require austenitic stainless steel or nickel alloy selected by the project engineer.
What documents prove low-temperature qualification?
The data package commonly includes the MTC, heat-treatment record and impact-test report showing specimen details, test temperature and results, plus traceability to the fitting heat or batch.
Can heavy-wall WPL6 caps be supplied?
Yes, subject to a technical review of size, exact wall, forming route, heat treatment and impact specimen requirements.
Request an A420 WPL6 pipe cap quotation
Include the minimum design temperature, impact test requirement, size, wall, quantity and documentation package for an accurate offer.
