BSPT Thread Chart Calculator for British Standard Pipe Taper Thread form where pressure-tight joints are made on the threads. The BSPT thread chart calculator shows sizes, dimensions, tolerances and designation for
jointing pipe threads for thread sizes from 1/16 to 6 according to ISO 7-1 standard. The thread form follows the British Standard Whitworth thread.
Some important notes from the ISO 7-1 standard:
- Threads are taper external, parallel internal or taper internal and are intended for use with
pipes suitable for threading and for valves, fittings or other pipeline equipment interconnected by threaded
-An appropriate jointing medium should be used on the
thread to ensure pressure-tight joints.
-ISO 7-2 gives details of methods of verification of jointing
thread dimensions and form and recommended gauging
- The symbols for pipe thread type: Rp - Parallel internal threads, Rc - taper
(conical) internal threads, R - external threads
- Designation: Internal thread - Parallel: Pipe thread ISO 7-Rp 1/2,
Internal Thread - Taper: Pipe thread ISO 7- Rc 1/2, External thread -
Always taper: Pipe thread ISO 7 - R 1/2
- The ISO 7-1 thread shall
be a right-hand thread unless otherwise specified.
- The taper is 1 to 16, measured on
British Standard Pipe Taper Thread (BSPT) per ISO 7-1
BSPP Thread: British Standard Pipe Parallel Thread
BSPT Thread: British Standard Pipe Taper Thread
Complete thread: The fully formed thread at both crest and root.
Gauge diameter: Major diameter of the external or internal thread
at gauge plane.
Gauge plane: Plane, perpendicular to the axis of the taper thread,
at which the major cone has the gauge diameter.
Gauge length: The distance from the gauge plane to the smaller end of the
thread on an external thread.
Major cone: The imaginary cone which just touches
all crests of a taper external thread or all roots of a taper internal thread.
Useful thread: All thread except washout thread.
Washout thread; Vanish thread: The thread which is not fully formed at the root.
Fitting Allowance: The external thread beyond the gauge plane which is required to provide an assembly with an internal thread at the upper limit of tolerance. It includes the wrenching allowance.
Wrenching Allowance: Useful thread
length which is provided to accommodate for wrenching beyond the position of handtight engagement.