AS ISO 7.2-2008 pdf free.Pipe threads where pressure-tight joints are made on the threads – Part2:Verification by means of limit gauges.
This revision of ISO 7-2 has been undertaken with the aim of providing a unified gauging system which could be adopted worldwide an thus eliminate the differing gauging results obtained with the use of gauges in accordance with ISO 7-2: 1982 and existing national practices. This revision also includes details of plain ring gauges to provide additional means of checking ISO 7-1 external threads and a parallel modified thread form check ring gauge for checking taper full form threaded plug gauges.
This part of ISO 7 specifies a process using limit gauges, for the validation of taper internal and external threads and parallel internal threads on piping systems components and other products, the dimensions and tolerances of which are detailed in ISO 7-1.
The gauging system described may not be suitable, without special precautions, for gauging of threads on injection moulded plastic workpieces.
This part of ISO 7 does not cover completely all the requirements necessary for full control of thread quality and dimensions. Additional control of tools and equipment and visual inspection during production are required to ensure complete compliance with ISO 7-1, for example the length of useful thread on internally threaded workpieces should be checked by direct measurement.
Annex A gives a summary of the gauges included in this part of ISO 7, together with details of the thread elements controlled by each gauge and gauge identification numbers.
In the event of a dispute over compliance with the requirements of ISO 7-1, the gauges in this part of ISO 7 are to be considered as decisive for the thread elements which they control on the workpiece.
5 Design of gauges
5.1 General
The taper full form threaded plug gauges and parallel full form threaded ring gauges (see 5.2 and 5.3) together with the taper plain ring gauges (see 5.4) have been chosen as representing the requirements for mating components or products within the tolerances of ISO 7-1.
Because of the 1:16 taper of the gauge and/or the threaded workpiece, it is possible to represent the maximum and minimum limits of diameter by means of tolerance steps within the axial length of the gauges.
The plain ring gauges included in this part of ISO 7, allow a combined check of the major diameter and the length of useful thread of externally threaded workpieces.
The taper modified thread form check plug gauge (see 5.5) and parallel modified thread form check ring gauge (see 5.6) for checking the manufacturing tolerances and wear allowances for the parallel full form threaded ring gauges and taper full form threaded plug gauges respectively, are made to a modified thread form.
Some dimensions given in this part of ISO 7 are more precise than the equivalent dimensions given in ISO 7-1. This greater precision is only intended to assist the gauge manufacturing process and is of no practical significance when using the gauges.