Issue 1 6. Any imperfection requiring repair during the process of demonstrating experience shall require that the manufacturer start again the complete demonstration process. Subsequently, after demonstration of experience isolated imperfections shall be handled in accordance with 6. However, multiple, systematic or process imperfections shall be investigated, corrected and the full demonstration of experience repeated.
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NOTE 1 This condition may be waived in those cases of different materials, where the hydrostatic pressure test would necessitate a redesign or where the pressure test can lead to an overloading of bolts during the pressure test.
In cases where piping is operated in the creep range, further considerations shall be taken into account. The applied test pressure shall include the amount of any static head acting in service and in testing at the point under consideration. For each piping spool, the test pressure shall be limited to such a level that it does not generate a design stress greater than that given in EN for the test conditions by reducing, if necessary, the test pressure.
For further details, see EN It shall be ensured that the structures, which are not provided by those responsible for the supply of the piping system, are able to support the loads created by the hydrostatic test. Prior to the hydrostatic test, the strength of temporary supports shall be verified. Air pockets in the piping system shall be avoided. Means shall be provided to prevent air pockets in pipe sections under test.
As a general rule, the hydrostatic test shall be performed with water. The quality of the water shall be such as to prevent both corrosion and any residual impurities. NOTE 3 In most cases the hydrostatic test may be performed with general supply water. The pressurizing fluid shall have a temperature sufficiently high that the risk of brittle fracture is avoided, see EN Where a pressurising fluid other than water is used, care shall be taken to identify any additional hazards associated with the fluid.
NOTE 4 For drinking water supply piping, drinking water should be used for the pressure test. Heavy walled piping shall not be pressurised until the metal temperature is approximately equal to that of the pressurisation medium. If the toughness of the material, or of the component, imposes a limit on the test temperature or on the rate at which the pressure is increased, account shall be taken of this and documented in the test data certificate. The piping system shall be held at the test pressure for a period of at least 30 min.
The pressure shall then be reduced to the design pressure and all components and welded joints subjected to a close visual examination of all surfaces and joints. During this examination, the piping shall show no signs of general plastic yielding. During the hydrostatic test, the external surface of the piping system shall be kept in such a condition 9. The hydrostatic test shall be passed if no leakage or visible plastic deformation is observed.
The details of the hydrostatic test shall be documented. The pressure shall be relieved before draining. Where vacuum conditions can occur when draining thin 9. The requirements of 9. If the inner surface is not accessible UT shall be performed before the pressure test. Attention is drawn to the fact that if the gas pressure is reduced to the piping system under test from high pressure storage, its temperature will fall.
Therefore the equipment provided by the piping systems manufacturer shall be such that the temperature of the gas entering the piping systems exceeds the minimum temperature indicated.
The pressure shall then be reduced after 10 min to the inspection pressure pi.
DIN EN 13445-5
DIN EN 13445-5/A1