GB/T 12250-2023Automatic steam traps - Marking (English PDF)

0 Foreword

The document was drafted according to the rules given in GB/T 1.1-2020, Directives for standardization, Part 1: Rules for the structure and drafting of standardizing documents.

It partly replaces GB/T 12250-2005, Automatic steam traps - Terms, marking, face-to-face dimensions, replacing the marking part of that edition. Against the marking part of the 2005 edition, and apart from structural adjustment and editorial change, the main technical changes are: the marking that shall be used has been changed, see Clause 5 and 5.2 of the 2005 edition; the marking that may optionally be used has been changed, see Clause 6 and 5.3 of the 2005 edition.

The document is a modified adoption of ISO 6553:2016, Automatic steam traps - Marking. The technical deviations from ISO 6553:2016 and their reasons are: the terms and definitions of maximum allowable pressure and maximum allowable temperature used in the document have been added, see Clause 3, to make the document easier to use; the normatively referenced GB/T 12220 replaces ISO 5209 and EN 19, see Clause 5, to suit the needs of practical application.

Attention is drawn to the possibility that some content of the document may involve patents. The body issuing the document bears no responsibility for identifying them.

The document is proposed by the China Machinery Industry Federation and falls under the jurisdiction of the National Technical Committee on Valves of Standardization Administration of China, SAC/TC 188.

The publication history recorded in the foreword: first published in 1989 as GB/T 12249-1989; first revised in 2005, when the contents of GB/T 12248-1989, Automatic steam traps - Terms, and GB/T 12250-1989, Automatic steam traps - Face-to-face dimensions, were merged in; the present edition is the second revision.

1 Scope

The document lays down the general requirements for the marking of automatic steam traps, the marking that shall be used, the marking that may optionally be used, and additional marking.

It applies to automatic steam traps.

2 Normative references

The content of the following document constitutes indispensable provisions of this document through normative reference in the text. For a dated reference, only the edition corresponding to that date applies; for an undated reference, the latest edition, including all amendments, applies.

GB/T 12220, Industrial valves - Marking, that is GB/T 12220-2015, a modified adoption of ISO 5209:1977.

3 Terms and definitions

The following terms and definitions apply to this document.

3.1 maximum allowable pressure: the highest pressure that the shell of an automatic steam trap is able to withstand continuously at a given temperature.

3.2 maximum allowable temperature: the highest temperature that the shell of an automatic steam trap is able to withstand continuously at a given pressure.

4 General requirements

The marking of an automatic steam trap may be placed on the body, or it may be marked on a nameplate, in which case the nameplate shall be firmly fixed to the body or to the cover. Care shall be taken that the marking is not covered up when the trap is installed and fixed.

5 Marking that shall be used

The marking that shall be used on an automatic steam trap is as follows: the name and, or, the trademark of the manufacturer; the maximum allowable pressure, in MPa; the maximum allowable temperature, in °C; the direction of flow of the medium, shown by an arrow; the body material; the nominal size, given as DN or as NPS; and the nominal pressure, given as PN or as Class.

The marking listed above shall comply with the provisions of GB/T 12220. The text then goes on to the case of an automatic steam trap that has no corresponding nominal pressure, PN or Class, but the sentence runs past the foot of the last page available in the scan and the remainder was not read.