PIPE CYLINDER SCREW-THREAD

A pipe cylinder screw-thread is a fastener and it is mainly used for connection of water- and gas pipelines and armature. The thread profile is shown in fig. 4.4.

Conventional denotations of a pipe cylinder screw-thread consist of (fig.4.5): Latin letter G; a nominal conventional size in inches; an accuracy class of middle diameter and general denotation for a left-hand thread in case of need.

Figure 4.4 - Pipe cylinder thread profile

Figure 4.5 - The conventional drawing of a pipe cylinder thread:

a) on a pipe; b) in an opening.

There are two accuracy classes A and B. An examples of a pipe cylinder screw-thread conventional denotation with a nominal size of 1 inch are: G1–A (for the accuracy class A); G1LH – B (for the left-hand thread of the accuracy class B).

It is necessary to remember, that the size of a pipe cylinder thread is not measured on an external diameter – d. Unlike metric and other threads the nominal size of a pipe cylinder thread is marked in inches, here it approximately equals the internal diameter of a pipe, where a screw-thread is cut on. A pipe cylinder thread of the same size can be cut on as on pipes with the different pipe wall thickness as well as on a continuous bolt. Parameters of a pipe cylinder thread according to State Standard 6357-81 are shown in table 4.2.

Table 4.2 - Sizes of a pipe cylinder thread for diameters from 1/4” to 2”(first row)