# BRITISH STANDARD PIPE PARALLEL (BSPP) THREAD DIMENSIONS

BSPP Thread Dimensions Calculator was developed to show British Standard Pipe Parallel Thread form where pressure-tight joints are not made on the threads. BSPP Thread Dimensions Calculator shows dimensions, tolerances and designation for fastening pipe threads for thread sizes from 1/16 to 6 according to ISO 228 - 1 standard. The thread form follows the British Standard Whitworth thread.

Some important notes from the ISO 228 - 1 standard:

- BSPP threads are not suitable joint where pressure-tightness is made on the thread. If assemblies with such threads must be pressure-tight, this should be made by compressing two tightening surfaces outside the threads, and by applying an appropriate seal.

- Threads are normally of the truncated form, with crests truncated to the limits of tolerance. There is an exception to this for internal threads, where they are likely to be assembled with external threads in accordance with ISO 7-1 (Pipe threads where pressure-tight joints are made on the threads — Part 1: Dimensions, tolerances and designation)

- For external threads, two classes of tolerances on the pitch diameter are specified; these are Class A and Class B. The choice between class A and class B depends on the conditions of application.

- The symbol for pipe thread type is G for external and internal threads.

- Designation: Internal thread - Pipe thread ISO 228- G 1/2 , External Thread - Pipe thread 1S0 228- G 1/2 A (For tolerance Class A).

 British Standard Pipe Parallel Thread (BSPP) per ISO 228-1

##### Calculator:

 INPUT PARAMETERS Parameter Value Pipe Thread Size 1/16 1/8 1/4 3/8 1/2 3/4 7/8 1 1 1/8 1 1/4 1 1/2 1 3/4 2 2 1/4 2 1/2 2 3/4 3 3 1/2 4 4 1/2 5 5 1/2 6

 RESULTS Parameter Symbol Value Unit Pipe Thread Size - --- --- Threads per inch n --- Pitch of Thread P --- mm Basic Height of Thread h --- Height of Sharp V Thread H --- Major Diameter of Thread D (= d) --- Pitch Diameter of Thread D2 (= d2) --- Minor Diameter of Thread D1 (= d1) --- Internal Pitch Diameter Lower Tolerance TD2 --- Upper Tolerance --- External Pitch Diameter Lower Tolerance (Class A) Td2 --- Lower Tolerance (Class B) --- Upper Tolerance (Class A / Class B) --- Internal Minor Diameter Lower Tolerance TD1 --- Upper Tolerance --- External Major Diameter Lower Tolerance Td --- Upper Tolerance ---