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Steel pipe defects and the concept of steel pipe defects

Views:0     Author:Site Editor     Publish Time: 2019-05-13      Origin:Site

Steel pipe defects and the concept of steel pipe defects

The friends who work in the rolling mill, must be familiar with the two terms "shortage of steel pipe" and "defect of steel pipe". While there's no such thing as "discolored," these two words make us feel uncomfortable. Because this represents the quality of steel pipe has been wrong.

 

So what are the defects and defects of steel pipe?

 

Imperfection means any inconsistencies or irregularities found in products that have been inspected according to methods provided by applicable standards.

 

Defect refers to a defect of sufficient size that is the basis for rejection of a product in accordance with applicable standards.

 

Yes, defects are more serious than defects, like the difference between illegal and criminal. It all means something is wrong, but not to the same degree.

 

Common defect tube body or pipe end include: pit, crack, folding, bump, bruised, gouge, layered, hairline, etc., if the depth does not exceed 12.5% of the specified wall thickness pipe, available artificial method for grinding to completely remove it, but the remaining wall thickness should be within the prescribed limits, grinding or machining should make the region and the tube body contour smooth transition. If the measured residual wall thickness of the tube body exceeds 87.5% of the total wall thickness of the tube body, it shall be considered as qualified product; otherwise, it shall be judged as unqualified product. At the same time, it should be noted that defects are not allowed to repair welding. Defects or defects found at the tube end shall be marked and the cause identified and mechanically removed as required.

 

Common steel pipe defects include:

 

(1) any quenching crack or arc burn;

 

(2) reduce the net effective wall thickness to below 87.5% for any surface cracking deficiency;

 

(3) any surface cracking defects with an area greater than 260mm2 detected by nondestructive testing (except appearance inspection) as specified in the standard or order;

 

(4) reduce the net effective wall thickness to less than 87.5% for any non-surface cracking defects of any weld within 1.6mm on both sides of the weld;

 

(5) any linear deficiency in any direction and depth of the inner and outer surfaces greater than the values shown in table 1.

 

Therefore, the steel pipe defects or defects, should be the first time to deal with. There are three main ways to deal with it:

 

(1) grinding or machining

 

Grinding or machining is not allowed for any quenching crack on the tube body;

If there are other defects within the specified limit of the residual wall thickness, the defects shall be removed by grinding or machining, and the radius of rounded corners shall be large enough to prevent sudden changes in the wall thickness;

If the grinding depth exceeds 10% of the specified wall thickness, the affected area shall be re-inspected to determine that the defect has been completely eliminated, and the re-inspection shall be: a with the same sensitivity as the inspection equipment used in the original inspection; or; B. Other NDE methods are adopted and the sensitivity is proved to be equal or higher than the original method.

(2) excision (ensure the remaining length is within the required range)

 

(3) rejection

 

Finally, bless you, cherish steel pipe, away from defects.


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