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ASME B16.9 Stainless Steel Butt Welding Pipe Cap SCH40 Pipe Plug End Cap
| Product Name | ASME B16.9 Stainless Steel Butt Welding Pipe Cap SCH40 Pipe Plug End Cap | Packing | Wooden Case Or Pallet |
|---|---|---|---|
| Product Type | Stainless Steel Cap | Temperaturerange | -196°C To 800°C |
| Processing | Cutting, Bending, Welding, Punching | Color | Sliver |
| Country Of Origin | China | Pressure | High Pressure |
| Payment Term | T/T | Surface Color | Silver |
| Use Area | Water,oil,gas | Thread Size | 1/2 Inch |
| Types | Seamless | Ordinary | 70mm;80mm;100mm; 150mm |
| Origin | China | Application | Pipe End Sealing / Pressure Vessels |
ASME B16.9 Stainless Steel Butt Welding Pipe Cap SCH40 Pipe Plug End Cap
1. Product Description
The stainless steel pipe cap is a robust end-closure component designed to terminate piping systems under a wide spectrum of operating conditions. It is manufactured predominantly from austenitic or duplex stainless steel, using either seamless construction (for sizes up to DN600) or welded plate construction (for larger diameters). The forming process involves hot stamping, cold pressing, or rotary forging to achieve a seamless transition between the cylindrical body and the dished end. The product is supplied in a solution-annealed and quenched condition (for austenitic grades) to ensure maximum corrosion resistance and optimal mechanical properties. Butt-weld ends are supplied with precision-ground bevels, while threaded ends are gauge-checked for perfect fit. Every cap is dimensionally verified using laser measuring equipment to ensure full interchangeability with mating pipes and fittings.
2. Product Applications
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Critical process lines in petrochemical crackers, hydrogen reformers, and ammonia synthesis plants where high integrity is mandatory.
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Cryogenic service (LNG terminals, liquid oxygen/nitrogen storage) using 304/316 grades with Charpy impact test verification at -196°C.
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High-purity water and steam systems in power generation (including nuclear island auxiliary systems) where chloride and dissolved oxygen control is essential.
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Sanitary processing (brewery, dairy, juice, and pharmaceutical filling lines) requiring electropolished internal surfaces to prevent biofilm formation.
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Marine and offshore platforms for seawater cooling, ballast, and firewater mains, using duplex grades to resist pitting and crevice corrosion.
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Building services – HVAC chilled water, hot water return, and fire sprinkler risers for permanent capping of test points and drain points.
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Temporary workshop use – as rugged protectors for pipe ends during multi-layer spool fabrication and hot-dip galvanising or coating operations.
3. Product Functions
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Permanent or temporary termination – allows designers to cap off future expansion points while maintaining pressure integrity.
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System drainage facilitation – when installed at low points with a small drain hole (factory or field-drilled), caps aid in complete system draining.
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Thermal expansion accommodation – by securely closing the end, the cap helps trap expansion fluid but can be combined with expansion joints upstream when needed.
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Vibration damping – the extra mass at the pipe end changes the natural frequency of the piping span, helping to mitigate resonant vibration.
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Identification and labelling platform – the flat or domed surface provides a convenient location for welding on tags, equipment numbers, or flow direction arrows.
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Positive shut-off during emergency repair – allows rapid isolation of a damaged section by capping the upstream end after shut-down.
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Inspection access closure – for large-diameter caps with manhole inserts (special design), they can serve as removable closures for internal inspection of vessels or headers.
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4.Key Specifications
| Parameter | Values / Guidance for Selection |
| Available Grades & Recommended Services | 304L – general duty, food contact, fresh water; 316L – marine, chemical, chlorides; 321 – high temperature (450–550°C); 310S – high temperature (up to 1000°C); Duplex 2205 – offshore, sour gas, high chloride; Super Duplex – seawater, acid environments. |
| Size & Schedule Compatibility | NPS ½–48 (DN15–1200). Schedule must match the connecting pipe: use same SCH for butt-weld; for threaded, wall thickness must meet minimum thread engagement requirements per ASME B1.20.1. |
| Connection Details | BW: bevel 37.5° ± 2.5°, root face 1.6 mm. SW: socket depth and bore per ASME B16.11. Threaded: taper 1°47' (NPT) or parallel with sealing compound (BSPP), length of engagement must be ≥ 5 full threads. |
| Manufacturing & Inspection Standards | ASME B16.9 / B16.11 / MSS SP-43; Material to ASTM A403 or A182. Inspection to ASME B16.9 dimensional tolerances and MSS SP-25 marking. |
| Pressure-Temperature Derating | For threaded caps, pressure rating decreases above 100°F (38°C): Class 300 drops from 600 psi to ~500 psi at 200°C. Always consult the ASME B16.5/B16.11 pressure-temperature tables. |
| Typical Weight (Approx., for SCH40S, 316L) | NPS 2: ~0.8 kg; NPS 4: ~3.2 kg; NPS 8: ~10.5 kg; NPS 12: ~22.0 kg; NPS 24: ~85.0 kg (welded type). Weights vary by shape and schedule – request a weight list for exact values. |
| Maximum Allowable Defect Standard | Accepts acceptance criteria per ASME Section VIII, Appendix 8 (for welded caps) or MSS SP-43 for light-wall; surface roughness NDT acceptance based on ASTM E165 – no cracks, no linear indications ≥ 1.6 mm. |
| End Preparation & Cleaning | Ends are degreased and free from oil, paint, and loose scale. Stainless steel wire brushes are used for final cleaning (carbon steel brushes are strictly prohibited to avoid iron contamination). |
| Shipping & Storage Advice | Store indoors or under cover. Avoid direct contact with carbon steel racks – use wooden pallets or rubber mats. For long-term storage, apply soluble oil on bevels and inspect passivation layer every 6 months. |
| Optional Supplementary Services | PMI (Positive Material Identification) at 100% for critical orders; extra corrosion allowance; weld overlay (cladding) on the inner surface for highly corrosive media; extended neck version for insulation flanges. |
FAQ
1. Are you trading company or manufacturer ? We are manufacturer ,You can see the certification.
2.How long is your delivery time? Generally it is 5-10 days if the goods are in stock. or it is 15-20 days if the goods are not in stock, it is according to quantity.
3. Do you provide samples ? is it free or extra ? Yes, we could offer the sample for free charge but need pay the cost of freight.
4. What is your terms of payment ? Payment<=1000USD, 100% in advance. Payment>=1000USD, 50% T/T in advance ,balance before shippment.

