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.
More: Flange Types Guide · What Is a Flange? · Schedule Chart · NPS vs DN · All Articles
Pipe cap purchasing checklist
For a pipe-end closure, send the pipe specification and the closure drawing or project requirement. Confirm whether the closure is intended to remain welded in place or must be opened for maintenance.
| Order detail | What to provide |
|---|---|
| Pipe fit | Specify nominal size, pipe outside diameter and required wall thickness at the weld end. |
| Cap geometry | State the dimensional standard and any required cap height, shape or installation clearance. |
| Material | Identify the material specification and grade, fabrication requirements and any project-specific testing. |
| Supply scope | List quantity, required marking, surface protection, inspection documents and packing requirements. |
Before you order
A product size or schedule is not a complete pressure-design approval. The cap, weld and connected pipe must be reviewed against the applicable project requirements. If repeated access is needed, review a bolted closure with the project engineer.
What is needed for a non-standard cap inquiry?
Provide a dimensioned drawing showing diameter, wall requirements, cap height and shape, together with the material, design conditions, quantity and inspection requirements.
Related products and references
Request a quotation — send your specification, quantity and drawing to info@pipingfitting.com.
Custom pipe cap manufacturing
Caps are often needed in a size or wall thickness that is not held on the shelf. We make caps to order: any nominal size, any schedule, welded construction where a seamless cap is not available, and prepared ends to match the pipe they close.
- Made to order in any size – from small bore up to large fabricated caps
- Wall thickness to suit the line – matching the run pipe schedule or a specified thickness
- End preparation – bevel, plain or machined to the drawing
- Material options – A234 WPB, A403 stainless, alloy steel, and low-temperature grades
- Documents and marking – material certificate, dimensional report, OEM stamps and shipping marks
Send your drawing or specification and we will confirm what can be made before quoting. Request a made-to-order quotation · info@pipingfitting.com.