scope:

1. Scope

1.1 This test method describes a procedure for obtaining a hydrostatic design basis for thermoplastic pipe materials, by evaluating stress rupture test data derived from testing pipe made from the subject material. The method is applicable to all known types of thermoplastic pipe and for any practical temperature and medium.

1.2 Unless the data approximate a straight line, when calculated using log-log coordinates, it is not possible to assign a hydrostatic design basis to the material. Data that exhibit high scatter or a "knee" give low (that is, conservative) extrapolated values when evaluated. In addition, the lower confidence level limits are not met and the data are classed as unsuitable.

1.3 The values stated in inch-pound units are to be regarded as the standard.

NOTE 1--Over 1200 sets of data, obtained with thermoplastic pipe and piping assemblies tested with water, natural gas, and compressed air, have been analyzed. None of the compounds in the lists of Recommended Hydrostatic Strengths and Design Stresses for Thermoplastic Pipe and Fittings Compounds in PPI Technical Report TR4, issued at intervals for over 12 years by the Plastics Pipe Institute, exhibit knee-type plots, that is, deviate from a straight line in such a manner that a marked drop occurs in stress at some time when plotted on equiscalar log-log coordinates. Data have been obtained for test periods over 120 000 h. It might be noted that some thermoplastic compounds that are not suitable or recommended for piping components do exhibit knee-type plots at 23°C (73°F); in these cases, very low results are obtained when the data are analyzed by this test method. Futher information on piping compounds may be found in the references at the end of this test method.

1.4 The experimental procedure to obtain individual data points shall be as described in Test Method D 1598, which forms a part of this test method. When any part of this test method is not in agreement with Test Method D 1598, the provisions of this test method shall control.

1.5 General references are included at the end of this test method.

1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.