Misalignment of thick-walled spiral steel pipe

Spiral steel pipe is a welded pipe made of strip steel coil as raw material, extruded at regular temperature, and welded by automatic double-wire double-sided submerged arc welding process. The spiral steel pipe sends the strip steel into the welded pipe unit, and after rolling by multiple rollers, the strip steel is gradually rolled up to form a circular tube blank with an opening gap. Adjust the reduction amount of the squeeze roller to control the gap between the weld seams at 1~3mm, and make the two ends of the weld joints flush.

The misalignment problem of thick-walled spiral steel pipe (SSAW pipe) refers to the phenomenon that the inner and outer walls of the steel pipe are asymmetrical and misaligned due to the influence of some factors during the steel pipe manufacturing process. This kind of problem often affects the use effect and safety of the steel pipe, and needs to be dealt with accordingly. Common misalignment processing methods include cutting, rolling and welding, and each method has its advantages and disadvantages. Therefore, when choosing a wrong edge treatment method, it is necessary to comprehensively consider the actual situation and handle it strictly in accordance with the operating specifications.

The treatment plan for the thick-walled spiral steel pipe that has been produced and has been misaligned is as follows:

1. Grind the position of the wrong side, and then carry out repair welding.
 
2. If the wrong side often occurs, the only option is to replace the device.

It is very necessary to analyze the reasons for the misalignment after the misalignment of the thick-walled spiral steel pipe. The following are the common reasons for the misalignment.
 
1. The sickle bend of the steel strip is an important factor causing the misalignment of the steel pipe. In the forming of spiral welded pipe, the sickle bend of the steel belt will continuously turn into a forming angle, resulting in changes in the weld gap, resulting in splits, misalignment and even overlapping.
 
2. When the butt welding seam reinforcement of the head and tail of the steel strip is large, if it is not handled properly during overforming, it is easy to cause a large misalignment.
 
3. Due to the poor shape and dimensional accuracy of the head and tail of the untrimmed steel strip, it is easy to cause the steel strip to be hard bent during butt jointing and cause misalignment.
 
4. The poor state of the edge of the steel strip is another important reason for the misalignment.
 
Common wrong edge processing methods

1. Cutting method: Use mechanical or manual cutting to remove the misplaced part

2. Rolling method: Use rollers to roll the misplaced part to restore it to its original shape

3. Welding method: use arc welding or gas welding to weld the misaligned part with the steel pipe body

Comparison of advantages and disadvantages of different wrong side processing methods

1. Cutting method: the operation is simple, but it will affect the overall strength and dimensional accuracy of the steel pipe

2. Rolling method: It can restore the overall strength and dimensional accuracy of the steel pipe, but requires professional technology and equipment

3. Welding method: It can guarantee the overall strength and dimensional accuracy of the steel pipe, but it needs to strictly control the welding quality

Conclusion: The misalignment of thick-walled spiral steel pipe is a common quality problem, and appropriate treatment methods are required to ensure its quality and safety. When choosing the wrong edge treatment method, various factors should be considered comprehensively according to the actual situation, and the treatment should be carried out in strict accordance with the operating specifications.

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