GB/T 12459-2025 Steel buttwelding piping fittings—Types and parameters
1 Scope
This document specifies types and codes, pressure design, dimension, surface profile, end groove, tolerance, marking and product quality certificate of DN 8 to DN 3400 (NPS 1/4 to NPS 136) steel buttwelding pipe fittings.
This document is applicable to steel buttwelding seamless and welded pipe fittings. Buttwelding pipe fittings made of other metal materials shall be used by reference.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 9124.2 Steel pipe flanges - Part 2: Class designated
GB/T 13401 Steel buttwelding pipe fittings - Technical specification
GB/T 28708 Specification for size selection of seamless and welded steel pipe used in piping engineering
3 Terms and definitions
No terms and definitions are listed in this document.
4 Types and codes
See Table 1 for types and codes of steel buttwelding piping fittings (hereinafter referred to as pipe fittings).
Table 1 Types and codes of pipe fittings
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5 Pressure design of pipe fittings
5.1 Pressure ratings (rated values)
The allowable pressure rating of pipe fittings designed and manufactured in accordance with this document can be calculated based on seamless straight pipes of the same specification, material and wall thickness that are connected to them. The nominal size (or outer diameter of the end), material grade and wall thickness (or pipe gauge number) marked on the pipe fitting represent the marking of the pressure grade.
5.2 Design of pipe fittings
5.2.1 The pipe fittings shall be designed with the same internal pressure endurance capability as their connected seamless straight pipes with the same specifications, materials and wall thicknesses.
Contents
Foreword II
1 Scope
2 Normative references
3 Terms and definitions
4 Types and codes
5 Pressure design of pipe fittings
6 Dimensions of pipe fittings
7 Surface profile
8 End groove
9 Tolerance
10 Marking
11 Product quality certificate
Annex A (Normative) Design verification test
Annex B (Normative) Design and calculation of pipe fittings
Bibliography
