GB 50661-2011Code for Welding of Steel Structures (English PDF)

2011 Beijing

"Code for Welding of Steel Structures" has been approved as a national standard with a serial number of GB 50661-2011 and shall be implemented from August 1, 2012. 4.0.1, 5.7.1, 6.1.1 and 8.1.8 are compulsory and must be enforced strictly. Authorized by the Research Institute of Standards and Norms (RISN) of the Ministry of Housing and Urban-Rural Development of the People's Republic of China, this code is published by China Architecture and Building Press.

Foreword

This code was jointly prepared by the Central Research Institute of Building and Construction of MCC Group Co., Ltd. and organizations concerned according to the requirements of the Ministry of Construction "Notice on Printing and Publishing 'Development and Revision Plan of National Engineering Construction Standards and Codes (second batch) in 2005' " (Jianbiao [2007] No.126).

This code provides the technical requirements on design of welding connections, manufacture, materials, procedure and quality control of steel structures as well as staffing. Meanwhile, in order to implement technical and economic policies of the nation and reflect the sustainable development concept in the steel structure construction field, this code not only controls the welding quality of steel structures, but also strengthen the requirements on energy conservation, material saving and environmental protection, etc.

During the preparation process this code, we summarized the practical experience and research achievements on steel structure welding in China in recent years, the drafting group conducted multiple monographic studies, sufficiently adopted the new technology, new procedure and new materials practically used in works, and used the international and foreign advanced standards for reference, solicited opinions from all sides, discussed and modified the specific contents repeatedly and finalizes it upon review.

The main contents of this code are: General Provisions, Terms and Symbols, Basic Requirement, Materials, Design of Welding Connections, Welding Procedure Qualification, Welding Procedures, Inspection, Weld Strengthening and Reinforcement, etc.

Provisions printed in bold type in this code are compulsory ones, and must be enforced strictly.

The Ministry of Housing and Urban-Rural Development is in charge of the administration of this standard and the explanation of the compulsory provisions of this code, and Central Research Institute of Building and Construction of MCC Group Co., Ltd. is in charge of the explanation of specific technical contents. All relevant organizations are kindly requested to sum up and accumulate your experiences in actual practice during the process of implementing this code. The relevant opinions and advice, whenever necessary, can be fed back to "Code for Construction of Concrete Structures" Administrative Group of Central Research Institute of Building and Construction of MCC Group Co., Ltd. (Address: No.33, Xitucheng Road, Haidian District, Beijing, 100088; E-mail: jyz3408@263.net) for future reference.

Aeronautical Project and Design Institute, BAOSTEEL Construction Co., Ltd., Baoshan Iron & Steel Co., Ltd., CISDI Engineering Co., Ltd., National Center of Quality Inspection & Testing for Hydro Steel Structure Ministry of Water Resources, Jiangsu Huning Steel Mechanism Co., Ltd., Zhejiang Southeast Space Frame Co., Ltd., Beijing Yuanda International Project Management Consulting Co. Ltd., Shanghai COSCO Kawasaki Heavy Industries Steel Structure Co., Ltd., Shaanxi Institute of Building Research, China Railway Shanhaiguang Bridge Group Co., Ltd., Zhejiang & Jinggong Steel Building (Group) Co., Ltd, Beijing 3j Int'l Steel Building Co., Ltd., Shanghai Baoye Group Construction Co., Ltd., China Construction Steel Structure Corp. Ltd., China Construction First Division Steel Structure Engineering Co., Ltd., Beijing General Municipal Engineering Design & Research Institute, China Electric Power Research Institute, Beijing Shuangyuan Engineering Consultation & Supervision Co., Ltd., Tianjin 20th Metallurgical Steel Structure Manufacturing Co., Ltd., DHI·DCW Group Co., Ltd., Wuhan Iron & Steel Heavy Industry Group Metallurgical Heavy Industry Co., Ltd. and Wuhan Iron & Steel Construction Engineering Group Metal Structure Co., Ltd.

1 General Provisions

1.0.1 This code is formulated with view to implementing national technical and economic policies in the steel structure welding, to achieving technical advancement, economic rationality, safety and usability, and to ensuring quality and energy conservation and environmental protection. 1.0.2 This code is applicable to the welding of structures bearing static load or dynamic load and with steel thickness not less than 3mm in industrial and civil steel structure engineering. The applicable welding methods in this code include shielded metal arc welding, gas-shielded arc welding, flux cored wire self-shield arc welding, submerged-arc welding, ESW, EGW, stud welding and their combination. 1.0.3 Steel structure welding must comply with the current relevant provisions of the nation on safety technology and labor protection, etc. 1.0.4 Steel structure welding shall not only comply with this code, but also shall comply with those specified in the in the current relevant standards of the nation.

2 Terms and Symbols

3 Basic Requirement

3.0.1 The welding difficulty in steel structure engineering may be classified into four levels, i.e. A, B, C and D according to those specified in Table 3.0.1. The carbon equivalent (CEV) of steels shall be calculated according to Formula (3.0.1). Note: this formula is applicable to non-hardened and tempered steel. Notes: a The overall welding difficulty is determined according to the most difficult level of the influencing factor in this b Steel classification shall meet the requirements of Table 4.0.5 in this code. 3.0.2 The design and construction organizations if steel structure welding engineering shall have the qualification corresponding to the engineering structure type. 3.0.3 The construction organization undertaking steel structure welding engineering shall meet the following requirements: It shall have corresponding welding quality management system and technical standards; […]

1 Welding technicians shall receive specific welding technology training and have

welding engineering or practical construction experiences of more than one year;

2 Welding technical leaders shall not only meet the requirements of Clause 1 in this article, but also shall have the technical titles above the intermediate level. As for the construction units undertaking the welding engineering Level C and Level D in term of difficulty, their welding technical leaders shall have senior technical titles;

5 Welders shall take technical qualification examination according to the requirements

of the steel type, welding nodal point form, welding method and welding position of the steel structure that they are engaged in, and shall obtain corresponding qualification certificate, their welding scope shall not be beyond the requirements of the qualification certificate.

6 Welding heat treatment personnel shall have corresponding profession skill. When using electrical heater for heating, operation personnel shall have received professional training. 3.0.5 The responsibilities of relevant personnel for steel structure welding engineering shall meet the following requirements:

1 Welding technicians are responsible for conducting welding procedure qualification, preparing welding process scheme and technical measures and instructions for welding operation or welding procedure sheet, as well as handling the welding technology problems during construction;

2 Welding inspection personnel are responsible for the inspection and control of the butt weld operation during the whole process and issuing inspection report;

3 Non-destructive testing personnel shall conduct flaw detection on the tested positions

according to the detection method and specified in the design document or corresponding specifications, and shall issue testing report;

4 Welders shall weld according to the requirements of welding procedure document; 5

Welding heat treatment personnel shall operate according to the heat treatment instruction and corresponding operation specifications. 3.0.6 The safety, health and operating environment of relevant personnel for steel structure welding engineering shall comply with those specified in the current relevant safety and health standards of the nation.

4 Materials

4.0.1 The steels and welding materials used in steel structure welding engineering shall 4.0.2 The re-inspection of chemical composition and mechanical property of steels and welding materials shall meet the requirements of the relevant current quality inspection and acceptance standards of the nation. 4.0.3 The selected steels shall be provided with complete weldability data, guiding welding procedure, hot working and heat treatment procedure parameters, welding joint property data of corresponding steels, etc.; new materials may be used in the engineering only after they pass the expert demonstration, review and welding procedure qualification. 4.0. […]

5 Design of Welding Connections

6 Groove form and size shall be selected according to different welding procedure

methods. 5.1.2 The identified weld symbol in the design drawing and detailed production drawing shall meet the relevant requirements of the current national standards "Weld Symbolic Representation on Drawings" (GB/T 324) and "Standard for Structural Drawings" (GB/T 50105). In the construction drawing of steel structure design, the following welding technology requirements shall be specified clearly:

2 The symmetrical groove or groove bias toward side plate [Figure 5.5.1-1 (b)] should

be adopted for the angle joint;

1 Where the joint strength requirements are met, the welding materials with good

deposited metal plastic performance should be selected; the welding materials with too high strength of deposited metal shall be avoided;

2 The low-hydrogen or ultra-low hydrogen welding materials and welding method

should be adopted for the welding;

7 For the vertically connecting weld of welding combination of H-beam and column

only bearing the static load, where web thickness is greater than 25mm, the full-penetration weld or partial penetration weld should be adopted [Figure 5.6.1-6 (b), (c)]; 8 The full-penetration weld [Figure 5.6.1-7 (a)] shall be adopted for the welding of box column and partition; where the electric arc welding cannot be adopted for the weld, the ESW should be adopted, and the weld should be arranged in symmetrical way [Figure 5.6.1-7 (b)]; 9 For the longitudinal and horizontal weld of composite column of steel pipe and concrete, the double-side or single-side full-penetration joint type (excluding the high-frequency welding) shall be adopted, the type of welding joint of longitudinal weld is shown in Figure 5.6.1-8; 10 In the pipe-ball structure, where the non-ribbed and ribbed types are adopted for the hollow ball welded by two half balls, the structure is shown in Figure 5.6.1-9. […]

1 As for members bearing dynamic load need not to undergo fatigue assessment, where

plug welding and groove welding are adopted, the spacing between edge of hole or groove and edge of member in the direction perpendicular to stress shall not be less than 5 times the thickness of this member and 2 times the width of hole or groove; […]

4 Surfacing welding shall not be adopted for blocking weld access hole.

6 Welding Procedure Qualification

8 The changes of current value and voltage value actually adopted for welding exceed

the recommended scope specified in product description for welding electrode. 6.3.2 As for consumable gas shielded arc welding, requalification shall be conducted where one of the following conditions changes:

1 Transformation between solid welding wire and flux cored wire; 2 The type of single shielding gas changes; the type and mixture ratio of multiple shielding gases change;

3 Shielding gas flow rate increases by above 25% or decreases by above 10%; 4 Swing amplitude of welding torch exceeds ±20% the acceptance value; 5 The change of current value, voltage value and welding speed actually adopted for welding exceed 10%, 7% and 10% the acceptance values respectively;

5 The change of current value and welding speed actually adopted for welding exceed

25% and 50% the acceptance values respectively;

5 The condition that current voltage characteristic of welding source being constant

9 Change of flux charge weight exceeds 30%.

6.3.6 As for EGW, requalification shall be conducted where one of the following conditions changes:

1 Model and diameter of welding wire change; 2 Type or mixture ratio of shielding gases change; 3 Shielding gas flow rate increases by above 25% or decreases by above 10%; 4 Welding current polarity changes; 5 The change of current value, wire feed speed and voltage value actually adopted for welding exceed 15%, 30% and 10% the acceptance values respectively;

6 Change of deviation from vertical position exceeds 10°;

8 Preheat temperature reduces 20℃ compared with that of acceptable welding process

10 Where arc welding is adopted, welding consumable changes.

6 The structure type of various prequalified welding nodal point welding nodal points

9 Where the variation range of welding procedure parameters exceeds the requirements

of Section 6.3 in this code according to Table 6.6.2-4 and Table 6.6.2-5, it shall not be prequalified. Note: the parameters in this Table are applicable to flat and horizontal welding position; the current of vertical welding shall be less than that of the flat and horizontal welding by 10%~15%. 6.6. […]

7 Welding Procedures

4 The repair welding shall meet those specified in Section 7.11 of this code.

4 It shall be ensured that the steel backing and weld metal is well-fused.

8 Welding procedure parameters, including welding current, welding voltage, welding

speed, welding layer and weld pass distribution;

9 Range of preheat temperature and interpass temperature range; 10 Post-weld stress relief treatment procedure;

11 Other necessary requirements.

7.10.2 As for shielded metal arc welding, solid welding wire gas shielded arc welding, flux-cored wire gas shielded arc welding and submerged arc welding (SAW), the breadth depth ratio of each weld shall not be less than 1.1. 7.10.3 Except the reinforced fillet weld used for groove weld, if the design requirements are met, the minimum fillet weld size shall be adopted and such size shall meet the requirements of Article 5.4.2. 7.10.4 As for shielded metal arc welding, semi-automatic solid welding wire gas shielded arc welding, semi-automatic flux-cored wire gas shielded arc welding, flux cored wire self-shield arc welding and automatic submerged arc welding, the maximum weld size of single pass welding should meet the requirements of Article 7.10.4. 7.10.5 Continuous welding shall be adopted for multilayer welding; after the completion of each pass, the welding slag and splash on the surface shall be timely cleaned; […]

8 Inspection

3 The Grade III weld shall be tested according to design requirements.