Throughout the fittings industry there are many types of connecting threads used in various applications, the most common of which ‘Pipe Threads’. There are basically two forms of pipe thread, taper and parallel.

For our thread identification charts of NPT, Tapered, Parallel and Straight threads, request it by email on: enquiries@waverleybrownall.co.uk

Taper Pipe Threads

These threads function by mating the male and female taper threads together, causing an ‘interference’ fit, where pressure-tight joints are made on the threads. A thread sealant is essential for this type of joint, that will also act as a lubricant to prevent galling during assembly. The correct sealant compatible with the application should be selected, the most widely used being PTFE tape.

It is recommended that 3-5 rounds of tape are applied in the direction of the thread to ensure adequate coverage and leak tightness of the joint is achieved. Other types of sealant should be used in accordance with the manufacturers recommendations.

If unsure, contact us on enquiries@waverleybrownall.co.uk and we will be able to assist you regarding threads.

Typical Taper Threads

NPT Taper Pipe Threads

• ANSI/ASME B1.20.1.

ISO-BSPT Taper Pipe Threads

• ISO 7/1 and BS21.

ISO taper pipe threads are similar in appearance to NPT threads, therefore care should be taken not to mix these threads.

Parallel Pipe Threads

These threads are not designed to seal on the thread, they are designed to seal on adjacent faces, by the use of a sealing gasket. Male threads are machined with a tapered undercut to centralise the gasket during assembly.

Parallel female threads are machined with a flat bottom face to accommodate an internal seal.

ISO-BSPP Parallel Pipe Threads

• ISO 228/1 and BS 2779.

Thread Protection And Identification

All male threads are supplied with colour coded protective plastic caps to prevent handling damages. Waverley Brownall products are packed securely in our branded packaging and engraved with identification codes as standard.

For more information on identification, branding and delivery,
call us on (+44) 01702 600014. Standard rates apply.