GB/T 23711.6-2019Test method for pressure vessels lined with plastics—Part 6:Anti pressure testing (English PDF)

5.3.2 Tightness test

5.3.2.1 For the plastic-lined shell, a safety test shall be performed before the tightness test of the steel pressure vessels lined with plastics.

5.3.2.2 The tightness test is performed after the lining is completed. The test pressure shall be determined according to Formula (2). For the selected test pressure, it shall fully consider the non-metallic sealing material and the permanent plastic deformation after the body is pressurized, so as to evaluate its influence on the subsequent sealing performance.

The meanings of pt, p, [sigma], [sigma]lt in the formula are shown in formula (1).

5.3.2.3 The test shall be carried out according to the following procedures and steps:

a) Inject water into the sample and exhaust the air in the closed cavity.

b) After the sample is filled with water, slowly increase the pressure; the pressure increase rate per minute is 10% of the test pressure; when the pressure is increased to 30% ~ 50% of the test pressure, stop the pressure increase for preliminary inspection; when there is no abnormal condition, continue to increase the pressure to the designed pressure and check for abnormal conditions. Continue to increase the pressure to the test pressure when there is no abnormality; the holding time of the test pressure shall be not less than 30 min. Under test pressure, no one shall be near the sample.

c) During the test, observe the pressure gauge at any time; pay attention to possible leakage, especially the connection and seal; during the pressure holding process, maintain the pressure unchanged.

d) After the sample tightness test is completed, release the pressure, and drain the water in the closed cavity. When discharging water, firstly open the pipe orifice above the position of the test sample; then, open the lower outlet; when releasing water, slow down the pressure release rate as much as possible, so as to prevent the vacuum sucking down the plastic lining.

5.5 Gas-liquid combined pressure test

5.5.1 For samples that cannot be filled with liquid due to load bearing and other reasons, inject some liquid first according to the load-bearing capacity; then, inject the gas, so as to perform a gas-liquid combined pressure test.

5.5.2 The test pressure shall be determined according to Formula (3); the holding time shall be not less than 10 min.

5.5.3 The test method shall be carried out according to the methods that are specified in 5.3 or 5.4, respectively.

5.5.4 After the gas-liquid combined pressure test, perform a spark testing in accordance with the method that is specified in GB/T 23711.1.

6.1 Hydraulic test

6.1.1 During the pressure holding process, the indicated value of the pressure gauge shall have no obvious change, and the sample shall have no abnormal sound.

6.1.2 During the test, use naked eyes to observe the sample; there shall be no visible deformation, no leakage or cracks.

6.1.3 If it meets the requirements of 6.1.1 and 6.1.2, it is judged as qualified.

6.1.4 If there is leakage in the flange part of the sample, after the pressure is released, tighten the fasteners on the flange to eliminate the leakage; perform the re-inspection according to 5.3.

6.2 Gas pressure test

In the pressure-holding process, there shall be no obvious change in the indicated value of the pressure gauge; the sample shall have no visible deformation, abnormal sound, or damage. If there is no leakage in the soap liquid or other leak detection liquid through test, it is judged to be qualified.

6.3 Gas-liquid combined pressure test

The gas-liquid combined pressure test shall be determined in accordance with the provisions of 6.1 and 6.2.