Stainless Steel Pipe Cap for Butt-Weld Pipe End Closure
The stainless steel pipe cap is a butt-weld fitting used to close the end of a piping system. Nonleak supplies ASME B16.9 pipe caps for welded pipeline termination, pressure testing sections, equipment connections and reserved branch ends. In addition, material options include 304/304L, 316/316L and duplex stainless steel for different project conditions.
As part of the butt-weld fittings range, this pipe cap provides a clean and permanent closure where future disassembly is not required. It is commonly used in water supply, HVAC, boiler systems, chemical pipelines, industrial process lines and utility piping systems.
How a Butt Weld Pipe Cap Works
A butt weld pipe cap closes the pipe end by welding the cap directly to the pipeline. The formed cap body contains the media inside the system, while the beveled weld end supports field welding and installation.
| Component | Function |
| Cap Body | Provides closed-end sealing for the piping system |
| Beveled Weld End | Supports butt-weld connection to the pipe end |
| Formed Head | Helps distribute pressure and maintain closure strength |
| Pipe Connection Area | Matches the pipe outside diameter and wall thickness |
Key Advantages of Using Pipe Caps
- Permanent Pipe End Closure: Suitable for welded systems where the pipe end does not need regular disassembly.
- Clean System Termination: Helps close unused branch ends, testing sections and reserved pipeline openings.
- Reliable Welded Connection: The butt-weld end provides a secure connection after proper field welding.
- Wide Material Selection: Available in stainless steel and duplex grades for different corrosion and strength requirements.
Engineering Features of Butt-Weld Pipe Caps
- Seamless or Welded Construction: Available according to size, wall thickness and project requirements.
- Accurate Formed Geometry: Supports stable pipe end closure and dimensional consistency.
- Consistent Wall Thickness: Helps maintain strength across the cap body and weld area.
- Beveled Weld End: Prepared for standard butt-weld installation on site.
Material Options for Stainless Steel Pipe Caps
Available materials can be selected according to media type, working environment, corrosion requirements and project specifications.
| Material Grade | Key Properties | Typical Applications |
| 304/304L | Excellent corrosion resistance, good formability | General chemical, food processing, water treatment |
| 316/316L | Superior chloride resistance, higher strength | Marine, pharmaceutical, coastal facilities |
| Duplex 2205 | Twice the yield strength of 316L, excellent SCC resistance | Offshore platforms, desalination, sour service |
| Duplex 2507 | Super duplex, extreme corrosion and pitting resistance | Highly aggressive chemical, high-chloride environments |
ASME B16.9 Pipe Cap Standard Compliance
Nonleak manufactures stainless steel pipe cap products according to project specifications and applicable butt-welding fitting standards, including ASME B16.9.
- ASME B16.9 – Factory-made wrought butt-welding fittings
- ASTM A403 – Wrought austenitic stainless steel piping fittings
- EN 10253 – Butt-welding pipe fittings
- DIN 2617 – Steel butt-welding pipe caps
- ISO / project-specific standards – Available upon request
Cross-section Diagram
Specification Table
| Nominal Pipe Size (NPS) | Outside Diameter At Bevel D (mm) | Center to End E(mm) |
| 1/2 | 21.3 | 25.4 |
| 3/4 | 26.7 | 25.4 |
| 1 | 33.4 | 38.1 |
| 1-1/4 | 42.2 | 38.1 |
| 1-1/2 | 48.3 | 38.1 |
| 2 | 60.3 | 38.1 |
| 2-1/2 | 73 | 38.1 |
| 3 | 88.9 | 50.8 |
| 3-1/2 | 101.6 | 63.5 |
| 4 | 114.3 | 63.5 |
| 5 | 141.3 | 76.2 |
| 6 | 168.3 | 88.9 |
| 8 | 219.1 | 101.6 |
| 10 | 273.1 | 127 |
| 12 | 323.9 | 152.4 |
| 14 | 355.6 | 165.1 |
| 16 | 406.4 | 177.8 |
| 18 | 457.2 | 203.2 |
| 20 | 508 | 228.6 |
| 22 | 558.8 | 254 |
| 24 | 609.6 | 266.7 |
| 26 | 660.4 | 266.7 |
| 28 | 711.2 | 266.7 |
| 30 | 762 | 266.7 |
Dimensions and tolerances can be confirmed according to ASME B16.9, project drawings or customer-specific requirements.
For complete dimensional data for all sizes (DN10–DN2000), download our Butt-Weld Cap Technical Documentation.
Key Applications
- Water Supply Systems: Pipe end closure in building and utility piping systems
- HVAC Systems: Termination points in heating and cooling pipeline layouts
- Boiler & Heat Exchanger Systems: End closure for equipment-related piping sections
- Chemical Processing: Stainless steel pipe end sealing for corrosive media lines
- Industrial Process Piping: Permanent closure for branch ends, test lines and reserved outlets
- Power & Utility Pipelines: Pipe end protection in service and maintenance areas
Quality Assurance & Testing
- Material Traceability: Heat number and material records available on request
- Dimensional Inspection: Outside diameter, wall thickness and cap height checked before shipment
- Surface Finish Verification: Visual inspection for surface quality and forming defects
- Non-Destructive Testing: PT/RT/UT available according to project requirements
- Chemical Analysis: Material composition verification available when required
- Hydrostatic or Pressure Testing: Available according to application requirements
Custom Options
- Special Materials: 304/304L, 316/316L, Duplex 2205, Duplex 2507 and other grades
- Custom Wall Thickness: Available according to pressure rating and project drawings
- End Preparation: Beveled ends, special weld preparation or customer-specified details
- Surface Treatment: Pickling, passivation, polishing or other finishing options
- Marking: Size, material grade, heat number, standard and customer logo available on request
