ISO 7-1:1994 pdf download – Pipe threads where pressure-tight joints are made on the threads
1 Scope
This part of IS0 7 specifies the requirements for thread form, dimensions, tolerances and designation for jointing pipe threads, sizes l/16 to 6 inclusive, for joints made pressure-tight by the mating of the threads. These 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 joints. An appropriate jointing medium should be used on the thread to ensure pressure-tight joints.
NOTES 1 Parallel external pipe threads are not suitable as jointing threads.
2 For pipe threads where pressure-tight joints are not made on the threads, see IS0 228-l.
3 ISO 7-2 gives details of methods of verification of joint- ing thread dimensions and form and recommended gauging systems.
2 Normative reference
The following standard contains provisions which, through reference in this text, constitute provisions of this part of IS0 7. At the time of publication, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this part of IS0 7 are encouraged to investigate the pos- sibility of applying the most recent edition of the standard indicated below. Members of IEC and ISO maintain registers of currently valid International Standards.
3 Definitions
For the purposes of this part of IS0 7, the following definitions apply (see also figures 3 and 5).
3.1 gauge diameter: Major diameter of the thread, whether external or internal.
3.2 major cone: Imaginary cone which just touches the crests of a taper external thread or the roots of a taper internal thread.
3.3 gauge plane: Plane, perpendicular to the axis of the taper thread, at which the major cone has the gauge diameter.
NOTE 4 For external threads the gauge plane is located at a distance equal to the nominal gauge length from the small end of the thread. For internal threads the gauge plane is located at a distance of half-pitch behind the face of the threaded part. This is in order to give consideration to the start of the thread that has been removed by chamfering. 3.4 gauge length: On an external thread, the dis- tance from the gauge plane to the small end of the thread.
3.6 complete thread: That part of the thread which is fully formed at both crest and root. NOTE 5 When there is a chamfer at the start of the thread not exceeding one pitch in length, this is included in the length of complete thread.
3.7 incomplete thread: That part of the thread which is fully formed at the root, but truncated at the crest by its intersection with the cylindrical surface of the product.
3.8 washout thread; vanish thread: That part of the thread which is not fully formed at the root. NOTE 6 The washout thread is produced by the bevel at the start of the threading tool.
3.9 useful thread: Complete thread plus incomplete thread, excluding the washout thread.
3.10 fitting allowance: Length of useful thread be- yond the gauge plane of an external thread required to provide for assembly with an internal thread at the upper limit of the tolerance. NOTE 7 Internally threaded pans will have a sufficient length to accommodate the fitting allowance, except when they have a free run-out. See 7.2.2.