Submerged arc steel pipe welding control measures

Submerged arc steel pipe welding control measures:

Submerged arc steel pipe has become the steel pipe for large-scale oil and gas transportation projects at home and abroad due to its large wall thickness, good material, and stable processing technology. In large-diameter submerged arc steel pipe welded joints, the weld and heat-affected zone are prone to various defects, while welding undercut, porosity, slag inclusion, lack of fusion, incomplete penetration, weld flash, burn through, and weld cracks It is the main form of welding defects, and it is often the origin of accidents in submerged arc steel pipes. The control measures are as follows:

A. Control before welding:

1. First, we must close the raw materials, and only after passing the inspection can we officially enter the construction site, and resolutely use unqualified steel.

2, followed by the management of welding materials. Check whether the welding materials are qualified products, whether the storage and baking system is implemented, whether the surface of the issued welding materials is clean and rust-free, whether the coating of the welding rod is in good condition, and whether there is mildew.

3. Again, the cleaning management of the welding area. Check the cleanliness of the welding area, and there must be no contamination such as water, oil, rust, and oxide film, which plays an essential role in preventing external defects of the weld.

4. The principle of first test welding and then welding should be implemented to choose the appropriate welding method.

B. Control during welding:

1. Check whether the specifications of the welding wire and flux are correct according to the welding procedure specification, to prevent welding accidents caused by the wrong use of welding wire and flux.

2. Supervise the welding environment. When the welding environment is not good (the temperature is lower than 0°C and the relative humidity is greater than 90%), corresponding measures should be taken before welding.

3. Before pre-welding, check the groove size, including the gap, blunt edge, angle, and misalignment, to determine whether it meets the process requirements.

4. Whether the welding current, welding voltage, welding speed, and other process parameters selected in the automatic submerged arc internal and external welding process are correct.

5. Supervise the welding personnel to make full use of the length of the arc-striking plate at the pipe end of the steel pipe during automatic submerged arc internal and external welding, and enhance the use efficiency of the arc-striking plate during internal and external welding, which helps to improve the pipe end welding.

6. Supervise whether the welding personnel clean up the slag before repairing welding, whether the joint has been processed, and whether there is oil, rust, slag, water, paint, and other dirt on the groove.