Butt weld pipe caps (end caps) in carbon steel, stainless steel and alloy steel – NPS 1/2″ – 48″, SCH10 – SCH160 per ASME B16.9. Sealing pipe ends permanently where a flange is not needed.
What Is a Pipe Cap?
A pipe cap is a domed fitting welded onto the open end of a pipe to close it. It seals the line permanently (cutting it open later requires cutting the cap off) and handles the same pressure as the pipe itself – unlike a blind flange, which bolts on and can be removed. Caps are the economical choice for dead legs, future tie-ins, hydrotest closures and vessel nozzles awaiting connection.
Specifications
| Item | Range |
|---|---|
| Size | NPS 1/2″ – 48″ (DN15 – DN1200) |
| Wall thickness | SCH10 – SCH160, STD, XS, XXS |
| Standard | ASME B16.9, DIN 2617, JIS B2311, GB/T 12459 |
| Materials | A234 WPB, A420 WPL6, A403 WP304/304L/316/316L |
| Shape | Ellipsoidal (2:1) standard; dished and flat on request |
| Certificates | EN 10204 3.1; 3.2 on request |
Pipe Cap vs Blind Flange
Choose a cap when the end is permanent or rarely opened – it is cheaper, lighter, welded full-strength, and cannot leak through a gasket. Choose a blind flange when the line will be reopened for maintenance, extension or equipment tie-in – the bolted joint opens without cutting. A common practice: cap during construction, replace with a flange when the tie-in date is known.
FAQs
What wall thickness should a cap have? Match the pipe schedule – a SCH40 cap welds directly to SCH40 pipe with full penetration.
Do you make caps above 24 inches? Yes – large-diameter caps up to 48″ are formed from plate; send size and schedule for a manufacturing review. Contact us.
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