Corrosion-Resistant Stainless Steel BW Cap for Pipe End Sealing

Overview

The Corrosion-Resistant Stainless Steel BW (Butt-Weld) Cap is a durable pipe fitting designed to permanently seal the ends of butt-weld pipelines in harsh, corrosive environments. Constructed from 304 or 316 stainless steel, this cap features a seamless design and butt-weld ends (ANSI B16.25 compliant), ensuring leak-proof performance and structural integrity in high-pressure systems.

Features

Premium Material & Design:

Seamless stainless steel (304/316) with a domed shape (elliptical or dished) to distribute pressure evenly, rated for working pressures up to 3,000 PSI (316 stainless steel, schedule 160).

Butt-weld ends with beveled edges (37.5°) for full-penetration welds, compliant with ASME B16.9 and suitable for critical pipeline termination.

Environmental Resistance:

316 stainless steel variant with 3.5% molybdenum resists pitting in seawater, chlorides, and sulfides, with a passivated surface extending service life by 50% in marine environments.

Temperature range: -250°C to 800°C, suitable for cryogenic LNG terminals and high-temperature furnace exhaust lines.

Installation & Compliance:

Available in sizes 1" to 48" NPS, with wall thicknesses matching pipeline schedules (40/80/160), ensuring compatibility with ASME B31.3 process piping codes.

Optional heat treatment (stress relief) for thick-walled caps to eliminate welding-induced stresses in high-temperature applications.

Quality Control:

100% hydrostatic testing (1.5x MAWP) and dimensional inspection, with material certificates (MTC) provided for traceability in regulated industries.

Application

Perfect for permanent pipe end sealing in extreme environments:

Oil & Gas Offshore: Sealing abandoned wellheads and subsea pipeline endpoints, with 316 stainless steel meeting NACE MR0175 for sour gas environments.

Chemical Plants: Terminating corrosive fluid lines in storage tanks and reaction vessels, compliant with OSHA standards for hazardous material containment.

Power Generation: Sealing steam pipeline endpoints in turbine bypass systems, with 304 stainless steel resisting oxidation at 550°C for 10+ years.

Marine Engineering: Sealing hull penetrations and ballast tank outlets, with 316 stainless steel enduring constant submersion in saltwater.

FAQ

Q: What is the difference between a cap and a blind flange?

A: A cap is welded directly to the pipe end, while a blind flange is bolted and reusable. Caps are permanent, flanges are removable.

Q: Can the cap be used for temporary pipeline closure?

A: Yes, but permanent welding is recommended for long-term use; for temporary closure, consider a blind flange or weld-olet with a removable plug.

Q: How to ensure proper weld penetration for thick-walled caps?

A: Use GTAW (TIG) with multiple pass welding, ensuring each pass achieves 100% penetration as verified by radiographic testing (RT).

Q: Are there fire-safe designs for caps in flammable environments?

A: Yes, caps can be designed with fire-safe materials (e.g., graphite gaskets for flanges), though caps themselves are solid and do not require gaskets.