Large Diameter Stainless Steel Pipe Cap ASME B16.9 Welded Tube Cap Fitting

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

• Critical process lines in petrochemical crackers, hydrogen reformers, and ammonia synthesis plants where high integrity is mandatory.

• Cryogenic service (LNG terminals, liquid oxygen/nitrogen storage) using 304/316 grades with Charpy impact test verification at -196°C.

• High-purity water and steam systems in power generation (including nuclear island auxiliary systems) where chloride and dissolved oxygen control is essential.

• Sanitary processing (brewery, dairy, juice, and pharmaceutical filling lines) requiring electropolished internal surfaces to prevent biofilm formation.

• Marine and offshore platforms for seawater cooling, ballast, and firewater mains, using duplex grades to resist pitting and crevice corrosion.

• Building services – HVAC chilled water, hot water return, and fire sprinkler risers for permanent capping of test points and drain points.

• Temporary workshop use – as rugged protectors for pipe ends during multi-layer spool fabrication and hot-dip galvanising or coating operations.

3. Product Advantages

• Outstanding resistance to pitting and crevice corrosion – especially with 316/316L and duplex grades, making them suitable for chloride‑rich environments.

• Excellent weldability – low carbon content (L‑grades) prevents intergranular corrosion after welding.

• Precision‑machined sealing surfaces – ensure leak‑tight closure under repeated thermal cycling and pressure fluctuations.

• High dimensional consistency – produced under strict quality control, with bevel angles, roundness, and wall thickness tolerances meeting or exceeding standard requirements.

• Versatile grade selection – from standard austenitic to super‑austenitic and duplex steels, covering a wide range of corrosive media and temperatures.

• Traceability – each cap is marked with heat number, material grade, size, and schedule, enabling full material traceability.

• Customizable surface finish – available in mill finish, pickled and passivated, or mechanically polished to mirror finish (Ra ≤ 0.8 µm for sanitary use).

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​4.Key Specifications

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.