304 Stainless Steel BSP Pipe Plug & Cap Fittings — Male Plugs & Female Blanking Caps

Match the fitting size to your pipe's nominal BSP thread size — not the pipe's outer diameter. For example, a 1/2" BSP plug fits a pipe with a nominal 1/2" BSP thread (actual OD is typically around 20.9 mm / 0.825"). Always verify with a thread gauge or check your existing fitting markings before ordering. If in doubt, measure the thread pitch and outer diameter of the male thread (or inner diameter of the female port) and cross-reference a BSP thread chart.

Pressure ratings vary by size and wall thickness. In general, 304 stainless steel BSP fittings in this size range are rated for moderate to high working pressures — typically 150–3000 PSI depending on size, with smaller sizes generally rated higher. Contact us to confirm the rating for your specific size before use in high-pressure systems.

Yes. 304 stainless steel offers good corrosion resistance in most outdoor and wet environments. It performs well against rain, humidity, and mild chemical exposure. For marine environments or applications with prolonged exposure to chlorides (saltwater, pool water), 316 stainless steel is generally recommended instead. In standard freshwater plumbing or outdoor air/gas applications, 304 is typically sufficient.

No. These fittings use BSP (British Standard Pipe) threads, which are not directly interchangeable with NPT threads. BSP and NPT have different thread angles (55° vs 60°) and different pitches at equivalent nominal sizes. Do not mix BSP and NPT fittings — doing so can cause leaks, cross-threading, or thread damage. If your system uses NPT, please contact us or search for our NPT-specific fittings.

A male plug has external (male) BSP threads and screws into a female-threaded port or socket to seal it — for example, blanking an unused port on a manifold or valve body. A female plug cap has internal (female) BSP threads and fits over a male-threaded pipe end or nipple to cap it off. Choose based on the thread type of the port or pipe end you need to blank.

For liquid or gas applications, applying PTFE thread seal tape (plumber's tape) to the threads is generally recommended to ensure a leak-free seal. BSP parallel threads (BSPP) in particular typically require a sealant or bonded seal washer, while tapered BSP threads (BSPT) can form a mechanical seal on their own but still benefit from PTFE tape. Wrap PTFE tape clockwise (when facing the thread end) for 2–3 turns before installation.

Most sizes can be installed with a standard pipe wrench or adjustable wrench. Avoid over-tightening, which can damage threads or distort the fitting. For smaller sizes (1/8" to 1/2"), hand-tight plus 1–2 turns with a wrench is generally sufficient when using PTFE tape. For larger sizes (2" and above), use a strap wrench or pipe wrench appropriate for the fitting diameter.