AS NZS 1462.29 pdf download

AS NZS 1462.29 pdf download.Methods of test for plastic pipes and fttings
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 T 1 , T 2 , …, T n : a) Each pair of adjacent temperatures shall be separated by at least 10 °C and at most 50 °C. b) One of the test temperatures shall be 20 °C or 23 °C. c) The highest test temperature T t,max shall not exceed the Vicat softening temperature, VST B50 , determined in accordance with ISO 2507-1:1995 minus 15 °C for glassy amorphous polymers, or the melting temperature determined in accordance with ISO 11357-3 minus 15 °C for semi- crystalline polymers. d) The number of observations and the distribution of internal pressure levels at each temperature shall conform to 4.2. e) To obtain an optimum estimate of σ LPL , the range of test temperatures shall be selected such that it includes the service temperature or range of service temperatures. Failures resulting from contamination may be disregarded, provided that the number of remaining observations conforms to 4.2.1. All valid data points shall be used in the calculations. For most materials, the test environment and test temperatures are specified in the relevant product standards.5.1.3  Detection of a knee and validation of data and model Use the procedure given in Annex B to detect the presence of any knee. After detecting a knee at any particular temperature, split the data set into two groups, one belonging to the first branch (data type A), the other belonging to the second branch (data type B). Fit the multiple linear regression as described in Annex A independently, using all first-branch (type A) data points for all temperatures and all second-branch (type B) data points for all temperatures. When studying the data for the occurrence of a knee, attention should be paid to the occurrence of a degradative failure. Such data (usually characterized by a nearly stress-independent line and visually recognizable) should not be considered for the calculation, but should only be used for determination of the extrapolation time (see 5.1.5).