BSP Fittings

BSP is a name shared by two connections that use one 55° thread form and seal in different ways. BSPP is parallel: the thread only clamps, while pressure is held by a 60° cone seat in the female end or a bonded seal washer crushed against a flat port face. BSPT is tapered and seals on the thread flanks, the way a pipe thread does.

Outside North America this is the standard, so it arrives with every imported pump, valve and machine. ISO 228 governs the parallel thread and ISO 7-1 the taper, and neither belongs in an NPT port. That is the common shop-floor mistake: BSP is cut at 55° and NPT at 60°, yet in 1/2 in. and 3/4 in. the two share a pitch, so parts spin together far enough to feel right before failing.

Where it's specified

• Imported hydraulic components — pumps, valves and cylinders arrive tapped BSP
• Flat-faced cast ports — a bonded seal washer works against the machined face, no compound
• Gauge work in metric plants — the 60° cone seat remakes repeatedly without tape
• Refitting imports to US hose — BSP-to-JIC and ORFS converters leave the port intact

Range and materials. Male and female BSPP with 60° cone seats, bonded seal stud ends, BSPT male and female, straights, elbows, tees, swivels, bulkheads and plugs, plus adapters to JIC 37°, ORFS, SAE ORB, NPT and metric, from 1/8 in. through 2 in., held in zinc-plated carbon steel, 316 stainless and brass.

Ordering notes. Identify the port before ordering: measure the thread along its length for parallel or tapered, then look into the female for a cone seat or a flat face, which decides between a coned male and a bonded seal end. Seal a parallel joint with the seat or washer, and keep sealant for BSPT. Where BSP must meet NPT, use a purpose-made adapter — forcing the threads ruins both.