For pipelines carrying flammable and explosive media, is it acceptable to use magnetic particle testing for the welds?
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For pipelines transporting flammable and explosive media (newly laid, not yet in use, with a working pressure of less than 2.5 MPa and a diameter of 2”), the construction party plans to use magnetic particle testing on the welds. They claim that it is possible to use magnetic particle testing due to the thin wall thickness of these pipes – is there any standard that supports this claim?
2-inch pipes can be subjected to radiographic testing; our 1-inch pipes are tested using the penetrant method, with a design pressure of 1.7 Mpa
Use X-ray testing for flaw detection; magnetic particle testing is not reliable.
No, it’s not possible. Magnetic particle testing and penetrant testing are both used to detect surface defects in welds, while RT is a method for detecting internal defects in welds; therefore, the two cannot be used interchangeably. Then, the major problems are usually internal defects rather than surface defects. Then, as for how non-destructive testing is carried out, it’s not up to the construction party to decide; first and foremost, it depends on the design documents, and if those are not available, then relevant standards apply.
The design documents specify the testing methods and the acceptable quality levels. . .
Both PT and MT are used for detecting surface defects; they have nothing to do with the thickness of the pipe wall. In theory, RT or UT should be used, as otherwise internal defects such as inclusions and lack of fusion cannot be detected