Surface Quality and Ultrasonic Testing of Seamless Steel Pipe for Structural Use (GB/T 8162-1999)
Seamless steel pipe is widely used in the construction and other industries due to its good strength, corrosion resistance and high temperature resistance. To ensure the quality of high-pressure seamless steel pipe, surface quality and non-destructive testing (NDT) tests are necessary. In this article, the related surface quality and ultrasonic test requirements and standards of seamless steel pipe for structural use GB/T 8162-1999 are introduced.
1. Surface quality requirements
GB/T 8162-1999 requires that the surface quality of seamless steel pipe for structural use should meet the following requirements:
① The surface of seamless steel pipe should be uniform and tidy in appearance, should not have any defects such as pits, dens, bumps and cracks, which affects pipe performance.
② The pipe wall should be smooth and flat, and the pipe body should be symmetrical within the permissible tolerance range.
③The outlet end shall not be inwardly curved and the edges are sharp.
④The surface is free of any cracks, folds, scale and oxide layer shedding.
⑤The surface should be free of any damage or scratches caused by handling, packaging and transportation.
2. Ultrasonic testing requirements
The ultrasonic testing requirements of GB/T 8162-1999 for seamless steel pipes for structural use are as follows:
① The material and billet of seamless steel pipe metal should be tested before pipe forming and piercing.
② The production inspection lot of seamless steel pipe shall meet the requirements of the ultrasonic flaw detection.
③ The steel pipe with an outer diameter greater than 31.8mm shall meet the requirements of ultrasonic flaw detection.
④ The ultrasonic flaw detection value is not more than the upper limit of the product standard.
3. Test conditions
For the ultrasonic testing of seamless steel pipe, GB/T 8162-1999 requires that the test conditions should be in accordance with the following requirements:
①The main measuring frequency used for the ultrasonic testing of seamless steel pipe is 2MHz~5MHz.
②Ultrasonic inspection should ensure reasonable incident angle, which is less than 75 degrees.
③The receiver and sender should hold the testing equipment firmly and parallel to the tube wall to ensure that the distance between the relative sound field formed by the sender and the receiver is within the range of 0~13mm.
④When inspecting long pipe joints, the distance between the testing points should not be less than 1/2 of the diameter of the pipe or 2m, whichever is smaller.
⑤The detection sensitivity should meet the requirements of GB/T 8162-1999.
⑥The requirements of sensitivity calibration and test environment shall comply with the relevant provisions listed in GB/T 8162-1999.
4.Conclusion
In conclusion, seamless steel pipes for structural use must meet the requirements of surface quality and ultrasonic testing. The surface should be tidy and uniform in appearance, without any defects such as pits, dens, bumps and cracks. For the ultrasonic testing of steel pipe, the main measuring frequency used for the ultrasonic testing is 2MHz~5MHz and the detection sensitivity should meet the requirements of GB/T 8162-1999. The requirements of sensitivity calibration and test environment shall also comply with the relevant provisions listed in GB/T 8162-1999. Following the standard of GB/T 8162-1999, the surface quality and ultrasonic testing of seamless steel pipe for structural use can be carried out successfully and its quality as well as safety can be ensured.
