The issue of test pressure for jacketed tubes
Thread Content
GB50235 specifies that the test pressure for the inner tube of a jacketed tube shall be determined based on the highest value of the internal or external design pressure. Article 11.5.4.3 of GB50316 states that the inner tube of a double-clad pipe shall be subjected to an internal pressure test at the test pressure corresponding to the higher of the internal and external pressures. It seems that the regulations for the two are not consistent; the test pressure is generally 1.5 times the design pressure, which is a significant difference. I would appreciate some advice from those who are more experienced.
Domestic standards often conflict with each other; this is a characteristic of the country. For our jacketed tube, the design pressure of the inner tube is 25 MPa, while that of the outer tube is 1.0 MPa. If pressure testing is carried out in accordance with the standards, just think about what the results will be. The test pressure is 25*1.5=37.5 MPa; how are such tests carried out on site? As a result, 100% flaw detection and leak testing were used in their place.
GB50235 specifies that it should be determined based on the higher internal and external design pressures; it does not state that testing should be carried out using the design pressures.
The original poster seems to have misunderstood the meaning of the statement that \"the test pressure for the inner tube of the double-wall tube should be determined based on the highest value between the internal and external design pressures.\" What this means is that the maximum of these two values should be used as the basis for the test pressure; this maximum value must then be multiplied by a test coefficient (such as 1.5). It does not mean that the maximum value itself should be used as the test pressure
Please take a closer look, OP – the two standards mean the same thing; you’ve misunderstood it.
The original poster misunderstood～～The inner tube is subjected to a hydrostatic test at 1.5 times its own height, while the outer tube does not need such a test；it is only tested at 1.5 times the design pressure of the outer tube. This is because the inner tube is subject to both internal and external forces