BS EN ISO 9080-2012 pdf download.Plastics piping and ducting systems一Determination of the long-term hydrostatic strength of thermoplastics materials in pipe form by extrapolation.
4 Acquisition of test data
4.1 Test conditions
The pipe stress rupture data shall be determined in accordance with ISO 1167-1 and ISO 1167-2. The determination of the resistance to internal pressure shall be carried out using straight pipes.
The mean outside diameter and minimum wall thickness of each pipe test piece shall be determined in accordance with ISO 3126.
For all calculations, the pipes tested shall be of the same nominal dimension and made from the same batch of material and come from the same production run.
For existing materials evaluated according to ISO/TR 9080:1992 or ISO 9080:2003, the initial data set may be complemented by additional data produced from other batches to meet the requirements of 4.2. In such case, the additional data should be spread regularly at each temperature and documented in the test report.
4.2 Distribution of internal pressure levels and time ranges
4.2.1 For each temperature selected, a minimum of 30 observations shall be obtained, spread over the
testing time. Internal pressure levels shall be selected such that at least four observations will occur above
7 000 h and at least one above 9 000 h (see also 5.1.5). In the event of prediction based on the second branch,
a minimum number of 20 observations is required for the second branches, with a minimum of 5 observations
per temperature.
4.2.2 For all temperatures, times to failure up to 10 h shall be neglected.
4.2.3 At temperatures < 40 °C, times to failure up to 1 000 h may be neglected, provided that the number of remaining observations conforms to 4.2.1. In that case, at the selected temperature(s), all points below the selected time shall be discarded. 4.2.4 Test pieces which have not failed above 1 000 h may be used as observations in the multiple linear regression computations and for the determination of the presence of a knee. Otherwise, they should be disregarded, provided that the number of remaining observations conforms to 4.2.1. 5 Procedure 5.1 Data gathering and analysis 5.1.1 General The method is based on multiple linear regression and calculation details given in Annex A. It requires testing at two or more temperatures and times of 9 000 h or longer and is applicable whether or not indications are found for the presence of a knee. 5.1.2 Required test data Obtain test data in accordance with Clause 4 and the following conditions, using two or more temperatures T1, T, ..., a) Each pair of adjacent temperatures shall be separated by at least 10 C and at most 50 DC. b) One of the test temperatures shall be 20 °C or 23 °C.BS EN ISO 9080 pdf download.