Lap Joint Stub End - Butt-Weld Pipe Fitting
A lap joint stub end is precision-machined with a radiused face to form a positive seal against a lap joint flange. It is supplied with the flange separately so the joint can spin freely, speeding up alignment and repeated assembly. Manufactured to BS EN 10253-2 and ASME B16.9, the machined lap face provides a reliable, repeatable sealing surface.
Each stub end is bevelled to ASME B16.25 for full-penetration butt welding and supplied with heat numbers and material test certificates for complete traceability from raw material to finished fitting.
Standards & Materials
Manufactured in accordance with BS EN 10253-2 and ASME B16.9 in carbon and stainless steel grades for UK process, food and pharmaceutical pipework.
| Attribute | Specification |
|---|---|
| Manufacturing Standard | BS EN 10253-2 / ASME B16.9 |
| Carbon Steel | ASTM A234 WPB |
| Stainless Steel | ASTM A403 WP304/304L/316/316L |
| Special Grades | Duplex & Super Duplex (UNS S31803 / S32205 / S32750), Alloy 20, Inconel 625 / 825, Monel 400, Hastelloy C-276 - available on request |
| Fabrication | Seamless or welded |
| Test Pressure | Up to 1500 psi |
| Lap Face Finish | Precision-machined radius to ASME B16.5 |
Dimensions & Sizes
Available from 1/2" (DN15) to 24" (DN600) in schedules 10, 40 and 80. The table below gives the lap face outer diameter (G), face length (F) and Schedule 40 wall thickness for representative sizes, to ASME B16.9.
| Nominal Size | DN | Lap Face OD G (mm) | Face Length F (mm) | SCH 40 Wall (mm) |
|---|---|---|---|---|
| 1" | 25 | 35 | 51 | 3.38 |
| 2" | 50 | 64 | 64 | 3.91 |
| 3" | 80 | 89 | 64 | 5.49 |
| 4" | 100 | 114 | 64 | 6.02 |
| 6" | 150 | 168 | 76 | 7.11 |
| 8" | 200 | 219 | 76 | 8.18 |
Performance & Benefits
The radiused lap face of a lap joint stub end concentrates the gasket seating stress into a narrow band, reducing the clamping load needed for a reliable seal. This design is particularly effective in applications involving thermal cycling, vibration or repeated dismantling. The free-spinning flange also eliminates bolt-hole misalignment issues during assembly, reducing installation time on site.
Typical Applications
Commonly specified in food processing, brewing, pharmaceutical and general process industries throughout the UK that value quick and easy line maintenance. Also used in heat exchanger connections, sampling systems, clean-in-place (CIP) lines and anywhere regular inspection or cleaning access is required.
Quality Assurance & Traceability
Every fitting is manufactured to BS EN 10253-2 and ASME B16.9 and supplied with full material traceability and EN 10204 Type 3.1 test certificates. Heat numbers are recorded throughout production to support inspection, QA and UK project-compliance requirements.
Supply & Delivery
Stocked at our Sheffield, UK facility and delivered nationwide across England, Scotland and Wales. We offer fast dispatch from stock with tracked UK delivery to site, and next-day options for common sizes.
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Which sizes and schedules are available?
Available from ½" (DN15) to 24" (DN600) in schedule 10, 40 and 80, in both metric and imperial sizes to suit UK installations.
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Can you provide material certificates?
Yes. Material test certificates and full traceability documentation are available with every order, to project and quality-management requirements.
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Why is a radiused lap face preferred?
A radiused (ring-type-joint style) lap face concentrates gasket seating stress into a narrow band, producing a more reliable seal with lower bolt loads compared to a flat-face stub end. It also tolerates thermal cycling and minor misalignment more effectively, making it the preferred choice for critical process services.
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Do you deliver across the UK?
We deliver nationwide throughout England, Scotland and Wales, with fast dispatch from stock and tracked deliveries to site.