Seamless Stainless Steel Pipe Cap ASME B16.9 304/316L High Pressure Tube Cap

Seamless Stainless Steel Pipe Cap ASME B16.9 304/316L High Pressure Tube Cap

1. Product Description

A stainless steel pipe cap is a non‑welded or welded end closure fitting that terminates the open end of a piping system. It is produced from solid stainless steel bars (for threaded and socket‑weld types) or from flat rolled plates (for butt‑weld types) using hot stamping, cold drawing, or forging techniques. The finished cap features a smooth internal transition and a uniform wall profile. Depending on the design pressure and service conditions, the end shape can be a standard elliptical (2:1 ratio), hemispherical (high pressure), dished (shallow), or flat cover (low pressure, non‑critical services). Precision machining ensures that the bevel ends (for butt‑weld) conform to ASME B16.25 with a 37.5° ± 2.5° bevel angle and a 1.6 mm root face, while threaded ends are manufactured to the appropriate gauge tolerance per ASME B1.20.1 (NPT) or ISO 7‑1 (BSPT). Each piece is heat‑treated (where applicable) to relieve residual stresses and optimise grain structure, followed by pickling and passivation to restore the passive chromium oxide layer.

2. Product Applications

• As a permanent end closure for main process lines in crude oil refining, natural gas treatment, and chemical synthesis plants.

• As a temporary seal for testing loops (hydrostatic, pneumatic, and leak testing) during construction and commissioning.

• For capping off unused branch connections in utility systems such as steam, condensate, cooling water, and compressed air.

• In high‑purity pharmaceutical and biotechnology applications, where the caps are electropolished and certified for low surface roughness (Ra ≤ 0.4 µm) to prevent product contamination.

• For offshore subsea pipelines, where caps with extra wall thickness and corrosion allowance are required to withstand seawater pressure and cathodic protection effects.

• In high‑temperature furnace piping (e.g., reformer tubes and heat exchanger headers) using heat‑resistant grades like 310S or 253MA.

• As protective covers for pipe ends during module fabrication and pre‑fabrication yard storage.

3. Product Advantages

• Superior resistance to stress corrosion cracking (SCC) – when using dual‑certified 304/304L or 316/316L, and especially with duplex grades for chloride‑laden environments.

• Excellent low‑temperature toughness – austenitic grades retain impact strength down to ‑196°C, suitable for cryogenic services (LNG, liquid nitrogen).

• Precise wall thickness control – using CNC machining or advanced forming dies, the wall thickness deviation is held within ±0.3 mm for sizes up to DN300, far exceeding standard tolerance requirements.

• Bevel preparation ready for welding – ends are cleaned, degreased, and protected with removable plastic caps to prevent contamination.

• Full traceability from melting to final product – each cap is stamped with a unique heat number, which correlates with mill test certificates (MTC) showing chemical composition and mechanical properties.

• Wide range of schedules and classes – from light wall (SCH5S) to extra heavy (SCH160, XXS), enabling selection for any pressure rating.

• Third‑party inspection compatibility – product can be supplied with inspection documents (EN 10204 3.1/3.2), and can undergo third‑party witness testing (e.g., TÜV, DNV, Bureau Veritas).

• Weld‑end protection – bevel faces are coated with anti‑rust oil and fitted with plastic end caps to avoid damage during shipment and handling.

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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.