GB/T 4791-2025Graphical symbols for pipeline accessories of ships (English PDF)

Foreword

This document complies with the provisions of GB/T 1.1-2020 "Standardization Work Guidelines Part

1.Structure and Drafting Rules of Standardization Documents". Drafting. This document supersedes GB/T 4791-2005 "Graphical Symbols for Ship Piping Fittings". Compared with GB/T 4791-2005, this document differs in that it includes the following. Aside from structural adjustments and editorial changes, the main technical changes are as follows:

a) Three new symbols have been added. double-walled tube, heating coil, and accompanying tube (see Table 1, sections 4.1.7, 4.1.8, and 4.1.9).

b) The orifice plate pattern has been modified (see

4.2.24 in Table 2,.2005 version);

c) A double blind flange drawing has been added (see

4.2.26 in Table 2);

d) The following have been removed. threaded pipe caps (pipe plugs), through-hole fittings (watertight), through-hole fittings (non-watertight), single-sided pipe seat plates, and double-sided pipe seat plates (see...). (Table 2, 2.2.25, 2.2.28~

2.2.31 in the.2005 edition)

e) The graphic symbols for ball valves and straight-through hose connector valves have been changed (see Table 4,

4.4.12 and 4.4.35; Table 4,

2.4.12 in the.2005 edition). 4.4.33);

f) The graphic symbols for the straight-through and right-angle cocks have been changed (see Table 4,

4.4.39 and 4.4.40; Table 4,

1 Scope

GB/T 4791-2025 is the Chinese national standard covering the symbols on a ship's piping diagram - the valves, strainers, traps and fittings, each with one agreed figure, so that a diagram drawn in one yard is read the same way by the crew and the surveyor years later. Issued on 31 October 2025, it has been in force since 1 May 2026, replacing GB/T 4791-2005.

This document specifies the graphic symbols for ship piping accessories. This document applies to the identification of graphic symbols for piping fittings in the design, construction, inspection, and repair of ships.

2 Normative references

This document has no normative references.

3 Terms and Definitions

This document does not contain any terms or definitions that need to be defined.

4 Graphic Symbols

4.1 Basic symbols are as per Table 1. Table