Technical Specifications for Structural Welding of Building Steel Structures JGJ81-2002 (19th)
1 Introduction
Structural welding is an integral part of the fabrication of most building steel structures, and the welding process is used to join two or more members of the same or different materials to form a complete joint. This document addresses the welding quality requirements of building steel structures. It provides comprehensive technical provisions for the quality assurance of structural welding for building steel structures. The regulations are intended to ensure that the quality of the welds is of sufficient strength, ductility and toughness to meet the design requirements of the particular structure and work environment.
2 Scope
These regulations cover the welding of the common building steel structures such as industrial and civil buildings, bridges and other structures made of steels, gray cast iron, aluminum-magnesium alloys, copper-nickel alloys, and other non-structural materials. It also covers welding preparations, welding symbol principals, pre-heat and post heat treatments, and protection of welds.
3 Definitions
3.1 weld: The joining of two or more pieces of metal through the fusion of the interfaces of the pieces
3.2 welding: The fusion of two or more pieces of metal by using an energy source such as a flame, electric arc, laser, or electron beam
3.3 base metal: The material being welded
3.4 filler metal: The material added to the weld that provides additional strength and stability
3.5 root pass: The initial pass for welding in a joint
3.6 seam weld: A weld made between two pieces in which the edges of the pieces are parallel in the same plane
3.7 welding symbol: A graphic representation of a weld used to identify the essential information about the weld
3.8 welder: The person who is responsible for the welding of structures
3.9 welding engineer: The person responsible for the quality control and approval of the welds
4 General Requirements
4.1 The welding of building steel structures shall comply with the current standards and regulations of the Peoples Republic of China.
4.2 The welding shall be performed by qualified welders under the guidance of a welding engineer.
4.3 The welding engineer shall be familiar with the design of the building steel structure, the welding method and the welding materials used, and possess the necessary qualifications and experience.
4.4 The welder shall possess the necessary certificates, qualifications and experience.
4.5 The welding materials shall comply with the relevant national standards.
4.6 The requirement for pre-heat and post-heat treatments shall comply with the relevant national standards.
5 Welding Symbol Principal
The welding symbol principal is used in the welding of building steel structures. The Welding Symbol Principal consists of three primary elements: a reference line, an arrow line and a symbol. The symbol indicates the type of weld or weld size while the arrow indicates the direction of weld. The symbol also includes symbols that indicate weld size, root pass, surface type and any other relevant information. The reference line is used to order the welds and is placed in the opposite direction of the arrow.
6 Preparation for Welding
6.1 The welding joints of the building steel structures shall be in accordance with the relevant national standards. The welding grooves and the end clearance shall comply with the requirement of the relevant national standards.
6.2 The welding experience and competence of the welders shall be verified.
6.3 The welding materials shall be inspected and qualified.
6.4 The welding procedure specification (WPS) shall be prepared as per the welding requirements of the building steel structure. The WPS shall be approved and implemented in accordance with the relevant national standards.
7 Pre-heat and Post-Heat Treatments
7.1 Pre-heat and post-heat treatments are normally performed to improve the weld quality, especially if the welding is done in high temperatures or with large welding currents.
7.2 Pre-heat and post-heat treatments shall be conducted in strict accordance with the relevant national standards. The pre-heat temperature shall be recorded and the condition of the weld shall be checked after the welding is completed.
7.3 The temperature for pre-heat and post-heat treatments shall be determined based on the material grade, joint thickness, welding current, ambient temperature and other relevant factors.
8 Protection of Weld
8.1 The exposed welds shall be protected from corrosion.
8.2 The painted surfaces of the structure shall be protected from welding spatter and heat damage.
8.3 The welding process shall produce no harmful fumes that are detrimental to the health of operators or the environment.
9 Quality Control
9.1 The welding of the building steel structure shall be supervised and inspected in strict accordance with the relevant national standards.
9.2 The welding engineer shall closely supervise the welding operations and inspect the welded joints after the welding is completed.
9.3 The welding engineer shall analyze the welding process and report any evidence of defective welds.
10 Final Acceptance
10.1 The welding of the building steel structure shall be inspected and accepted according to the relevant national standards and the specifications of the construction drawings.
10.2 The welds shall be tested in accordance with the relevant national standards.
10.3 The welds that pass the tests shall be considered acceptable.
11 Documentation
11.1 The welding documentation shall include the Welding Procedure Specification, the Welder Qualification Certificate, the Inspection Records, the Qualification Test Reports, the Final Weld Inspection Report, the Material Purchasing Checklist, the Material Qualification Certificates, and any other applicable records.
11.2 All welding documentation shall be stored for future inspections and reference.
These regulations provide comprehensive technical provisions for the quality assurance of structural welding for building steel structures. The regulations are intended to ensure that the quality of the welds meet the design requirements of the particular structure and work environment and comply with relevant national standards. The welding engineer shall closely supervise the welding operations, inspect the welds and documented evidence of quality. The welds that have passed all tests shall be considered acceptable.
