Sch 2 para 6 Experimental design methods
(1) The design of the equipment may be validated, in all or in part, by an appropriate test programme carried out on a sample representative of the equipment or the category of equipment. (2) The test programme must be clearly defined prior to testing and accepted by the approved body responsible for the design conformity assessment module, where it exists. (3) The test programme must define test conditions and criteria for acceptance or refusal and the actual values of the essential dimensions and characteristics of the materials which constitute the equipment tested must be measured before the test. (4) Where appropriate, during tests, it must be possible to observe the critical zones of the pressure equipment with adequate instrumentation capable of registering strains and stresses with sufficient precision. (5) The test programme must include— (a) a pressure strength test, to check that, at a pressure with a defined safety margin in relation to the maximum allowable pressure, the equipment does not exhibit significant leaks or deformation exceeding a determined threshold, for which the test pressure must— (i) be determined on the basis of the differences between the values of the geometrical and material characteristics measures under test conditions and the values used for design purposes; (ii) take into account the differences between the test and design temperatures; (b) where the risk of creep or fatigue exists, appropriate tests determined on the basis of the service conditions laid down for the equipment, for example hold time at specified temperatures, number of cycles at specified stress-levels; (c) where necessary, additional tests concerning other factors referred to in paragraph 4 such as corrosion and external damage.