【国外标准】 Standard Test Method for Pressure Rating Poly(Vinyl Chloride) (PVC) Plastic Pipe Fittings, Schedule 40 and 80 Socket-Type

4.1 The procedure for establishing the long-term pressure rating of fittings starts with an extrapolation of a regression line that is based on fitting failure data with respect to time, when assemblies are tested in accordance with Test Method D1598. The pressure-versus time to failure data are obtained using water at 73 °F in assemblies that are immersed in a water or air environment. The extrapolation is made in such a manner that the long-term hydrostatic pressure rating is determined for these conditions.4.2 The pressure design basis is determined by considering the following items and evaluating them in accordance with 6.3.4.2.1 Long-term hydrostatic pressure-strength at 100 000 h,4.2.2 Long-term hydrostatic pressure-strength at 50 years4.3 The fitting pressure rating may be calculated by multiplying the pressure design basis (PDB) by the appropriate design factor (DF).1.1 This test method covers a procedure for establishing Pressure Rating for PVC schedule 40 and 80 socket-type fittings by evaluating fitting failure test data derived by testing water-filled assemblies of pipe and fittings.1.2 Unless the data approximates a straight line, when calculated using log-log coordinates, it is not possible to assign a pressure rating to that product or sample of product. Data that exhibit high scatter, or a downward curve, due to low long term data, will give low extrapolated values that are more conservative when calculated using log-log co-ordinates. In addition, this downward curve will show as higher scatter, and where the lower confidence level limits are not met the data shall be classified as unsuitable. (See Note 1)NOTE 1: This test method is similar to that used in Test Method D2837, which has been used for about 30 years to establish the HDS of plastic pipe materials and is the basis for all pressure ratings assigned to plastic pipes.1.3 The products covered by this test method are schedule 40 or 80 molded PVC fittings that conform to Specifications D2466 or D2467.1.4 The pressure ratings developed using this test method applies only to fittings identical to the ones that were tested. Some variables that will affect the pressure rating are – pipe size, pattern, mold design, material, and molding conditions.1.5 The values in inch-pound units are to be regarded as the standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.1.6 The testing procedure used to obtain the fitting failure data shall be as described in those sections of Test Method D1598, that are referenced in Section 6 of this test method.1.7 The products covered by this test method are intended for use in the distribution of pressurized liquids at 73 °F. When appropriate, the design engineer must consider the effects of elevated temperature and chemical compatibility of the liquid with the fitting material and apply necessary design factors.1.8 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.NOTE 2: Pressurized (compressed) air or other compressed gases contain large amounts of stored energy which present serious safety hazards should a system fail for any reason.1.9 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.