IBR Approved · Buttweld Fittings
Lap Joint Stub End Manufacturer
Type A and Type B stub ends to ASME B16.9 / MSS SP-43 — used with lap joint backing flanges. In carbon, alloy, stainless and duplex steel, 1/2" to 24" NB. IBR approved with Form III-C, EN 10204 3.1 / 3.2 traceable.
Overview
A stub end is buttwelded to the pipe and paired with a loose lap joint (backing) flange that slides over the barrel. Only the stub end contacts the fluid, so the backing flange can be a cheaper material and can rotate freely for bolt-hole alignment. This makes stub ends ideal for frequently dismantled joints and for expensive alloy piping, where only the stub end need be the alloy grade.
Every stub end is produced to the applicable material specification with full traceability, supplied with EN 10204 3.1 or 3.2 test certificates and, for boiler and steam service, IBR Form III-C certification.
Stub End Types & Standards
| Type | Barrel / Lap | Standard | Matches |
|---|---|---|---|
| Type A | Long barrel, radiused lap | ASME B16.9 | Slip-on / lap joint flanges |
| Type B | Short barrel, larger lap OD | MSS SP-43 | Lap joint flanges |
| Short / Long pattern | Per flange face | ASME B16.9 | To customer flange spec |
Available Material Grades
Stub ends are supplied in our full material range. Click a grade for full specification, chemistry and mechanical data:
Technical Specifications
| Parameter | Range |
|---|---|
| Size range | 1/2" to 24" NB (larger on enquiry) |
| Schedules | SCH 10, STD, XS, SCH 80, SCH 160, XXS |
| Dimensional standard | ASME B16.9 / MSS SP-43 |
| End preparation | Bevel end per ASME B16.25 |
| Certification | EN 10204 3.1 / 3.2 · IBR Form III-C |
| Testing | PMI, dimensional, DP / RT as specified |