GB/T 12770-2025 Welded stainless steel tubes for mechanical structures English, Anglais, Englisch, Inglés, えいご
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ICS 77.140.75
CCS H 57
National Standard of the People's Republic of China
GB/T 12770-2025
Replaces GB/T 12770-2012
Welded stainless steel tubes for mechanical structures
Issue date: 2025-08-29 Implementation date: 2026-03-01
Issued by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
the Standardization Administration of the People's Republic of China
Contents
Foreword
1 Scope
2 Normative References
3 Terms and Definitions
4 Classification and Designations
5 Ordering Information
6 Manufacturing Process
7 Technical Requirements
8 Test Methods
9 Inspection Rules
10 Packaging, Marking and Quality Certificate
Welded Stainless Steel Tubes for Mechanical Structures
1 Scope
This document specifies the classification and designations, ordering information, manufacturing process, technical requirements, test methods, inspection rules, packaging, marking and quality certificates for welded stainless steel tubes used in mechanical structures.
This document applies to welded stainless steel tubes (hereinafter referred to as "steel tubes") for mechanical, automotive, railway vehicles, marine engineering, oil and gas engineering, and other structural applications.
2 Normative References
The following documents contain provisions which, through reference in this text, constitute provisions of this document. For dated references, subsequent amendments (excluding corrigenda) or revisions to these documents do not apply. For undated references, the latest edition of the document (including any amendments) applies.
GB/T 222 Steel and alloy - Permissible variations of product chemical composition
GB/T 223.4 Iron, steel and alloy - Determination of manganese content - Potentiometric or visual titration method
GB/T 223.9 Iron, steel and alloy - Determination of aluminium content - Chrome azurol S spectrophotometric method
GB/T 223.11 Iron, steel and alloy - Determination of chromium content - Visual titration or potentiometric titration method
GB/T 223.18 Chemical analysis methods for iron, steel and alloy - Determination of copper content - Sodium thiosulfate separation-iodine titrimetric method
GB/T 223.19 Chemical analysis methods for iron, steel and alloy - Determination of copper content - Neo-cuproin-chloroform extraction photometric method
GB/T 223.23 Iron, steel and alloy - Determination of nickel content - Dimethylglyoxime spectrophotometric method
GB/T 223.25 Chemical analysis methods for iron, steel and alloy - Determination of nickel content - Dimethylglyoxime gravimetric method
GB/T 223.26 Iron, steel and alloy - Determination of molybdenum content - Thiocyanate spectrophotometric method
GB/T 223.28 Chemical analysis methods for iron, steel and alloy - Determination of molybdenum content - α-Benzoinoxime gravimetric method
GB/T 223.36 Chemical analysis methods for iron, steel and alloy - Determination of nitrogen content - Distillation-neutralization titration method
GB/T 223.37 Iron, steel and alloy - Determination of nitrogen content - Distillation-indophenol blue spectrophotometric method
GB/T 223.40 Iron, steel and alloy - Determination of niobium content - Sulfochlorophenol S spectrophotometric method
GB/T 223.59 Iron, steel and alloy - Determination of phosphorus content - Bismuth phosphomolybdate blue and antimony phosphomolybdate blue spectrophotometric methods
GB/T 223.60 Iron, steel and alloy - Determination of silicon content - Gravimetric method
GB/T 223.63 Iron, steel and alloy - Determination of manganese content - Sodium periodate (potassium periodate) spectrophotometric method
GB/T 223.84 Iron, steel and alloy - Determination of titanium content - Diantipyrinylmethane spectrophotometric method
GB/T 223.85 Iron, steel and alloy - Determination of sulfur content - Infrared absorption method after combustion in an induction furnace
GB/T 223.86 Iron, steel and alloy - Determination of total carbon content - Infrared absorption method after combustion in an induction furnace
GB/T 228.1 Metallic materials - Tensile testing - Part 1: Method of test at room temperature
GB/T 242 Metallic tubes - Drift-expanding test
GB/T 245 Metallic materials - Tubes - Flaring test
GB/T 246 Metallic materials - Tubes - Flattening test
GB/T 2102 Acceptance, packaging, marking and quality certificate for steel tubes
YB/T 4395 Steel - Determination of molybdenum, niobium and tungsten contents - Inductively coupled plasma atomic emission spectrometry
YB/T 4396 Stainless steel - Determination of multi-element contents - Inductively coupled plasma atomic emission spectrometry
3 Terms and Definitions
The terms and definitions established in GB/T 30062 apply to this document.
4 Classification and Designations
4.1 Steel tubes are classified into 3 types according to delivery condition, with the types and designations as follows:
a) Welded state WW
b) Cold-drawn (cold-rolled) state WC
c) Heat treatment state T
4.2 Steel tubes are classified into 5 types according to surface condition, with the types and designations as follows:
a) Ground state SP
b) Polished state SB
c) Shot-blasted state SS
d) Picked state SA
e) Un-treated state SNB (or no designation)
4.3 Steel tubes are classified into 2 grades according to dimensional accuracy, with the grades and designations as follows:
a) Ordinary grade PA
b) High grade PC
