【国外标准】 Standard Practice for Microwave Examination of Polyethylene Butt Fusion Joints

5.1 Polyethylene piping has been used instead of steel alloys in the petrochemical, power, water, gas distribution, and mining industries due to its resistance to corrosion, erosion, and reliability. Recently, polyethylene pipe has also been used for nuclear safety related cooling water applications.1.1 This practice covers microwave (MW) examination of butt fusion joints made entirely of polyethylene for the purpose of joining polyethylene piping or vessel parts.NOTE 1: The notes in this practice are for information only and shall not be considered part of this practice.NOTE 2: This practice references HDPE and MDPE for pipe applications as defined by Specification D3350.1.2 MW examination detects differences between the dielectric constant(s) of the materials being examined. These differences may be due to material construction (expected) or flaws such as voids, cracks, or foreign material intrusion (unexpected).1.3 The butt fusion joining process can be subject to a variety of flaws including, but not limited to, lack of fusion, particulate contamination, inclusions, and voids.1.4 This practice is intended for use on polyethylene butt fusion joints of pipe diameters of 4 in. to 65 in. (100 mm – 1650 mm) and wall thickness of 0.5 in. to 4 in. (12 mm – 100 mm). Greater and lesser thicknesses and smaller diameters may be tested using this standard practice if the technique can be demonstrated to provide adequate detection on mockups of the same wall thickness and geometry.1.5 This standard practice does not address microwave examination of electrofusion joints, socket joints, or saddles.1.6 This standard details inspection requirement only. Accept/reject criteria must be established contractually and is typically done using multiple samples with mechanical test (that is, tensile test) validation.1.7 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.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.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.