Welding Procedure Specifications for Steel Structures of JGJ81-2002
Welding procedure specifications, commonly referred to as WPS, are documents approved by qualified welding personnel or welding engineers (often referred to as WPQRs) that contain instructions and procedures for welding process and welding parameters, including welding equipment and consumables; electric arc welding; flux-cored arc welding; and shield metal arc welding. In the welding of steel structures of JGJ81-2002, welding procedure specifications shall be established in accordance with relevant standards.
Firstly, the elements to be determined for the WPS for steel structures of JGJ81-2002 shall include base metal, welded joint type, welded joint details, welding position, welding procedure, welding operation method and welding consumables.
The base metal of steel structures of JGJ81-2002 welding is mainly carbon structural steel, low alloy steel and stainless steel; the main welded joint type includes groove weld and fillet weld.
Groove Welds conformance to dimensional tolerances is based on the tolerances given in the relevant standard and the results of weld joint tests. Particular attention should be paid to the groove angle and root series.
The fillet weld of steel structures of JGJ81-2002 emphasizes the welding operators skill and ability and shall be made in accordance with the position given in the standard. Groove weld should be prefabricated after careful inspection and correction if necessary, so as not to affect the welding quality.
The welding position of steel structures of JGJ81-2002 mainly includes horizontal position, vertical position, overhead position and flat position. The welding position should be noted in the WPS.
The welding procedure of steel structures of JGJ81-2002 should be used for various welding positions, welding processes and welding internal and external welds to achieve Auto Control by providing operating parameters such as welders operating temperature, welding voltage, welding current, welding speed and the sequence of welding and recording any parameters changes in the welding process.
The welding operation methods of steel structures of JGJ81-2002 are mainly arc welding, gas welding and manual welding. For arc welding, it is necessary to take measures to prevent misoperation by the welder, such as requiring the welding rate not be too fast, and welding under the condition of high arc stability. Gas welding should require smooth welding process and strict control of welding temperature to ensure that the molten steel is effectively protected by the shield gas. Manual welding should ensure that the welders are skillful, and the craftsmanship is standardized.
The welding consumables of steel structures of JGJ81-2002 should select welding rods, welding electrodes and welding wires according to the characteristics of steel structures and welding process requirements. For low hydrogen welding wires, measures should be taken to avoid moisture absorption before welding.
In conclusion, when establishing WPS for steel structures of JGJ81-2002, qualified welders, welding engineers and other personnel should pay attention to various factors and requirements, including welding position, welding operation method, and welding consumables, so as to select welding operation, welding process and welding parameters to meet the requirements of mechanical properties of welded joints and their structure dimensions.
