【国外标准】 Standard Practice for Flux Leakage Examination of Ferromagnetic Steel Tubular Products

5.1 This practice outlines a procedure for examining ferromagnetic tubular products using the flux leakage method. If properly applied, this method is capable of detecting the presence and location of significant longitudinally or transversely oriented discontinuities, such as pits, scabs, slivers, gouges, roll-ins, laps, seams, cracks, holes, and improper welds in ferromagnetic tubes under inspection. In addition, the severity of a discontinuity may be estimated and a rejection level set with respect to the magnitude of the electromagnetic indication produced by the discontinuity.5.2 The response from natural discontinuities can be significantly different from the response for artificial discontinuities, such as drilled holes or notches of equivalent depth. For this reason, sufficient work should be done to determine the conditions necessary to detect and mark natural discontinuities whose characteristics will adversely affect the serviceability of the tube, in order to establish acceptance criteria between the supplier and purchaser.1.1 This practice covers the application and standardization of equipment using the flux leakage test method for detection of outer surface and inner surface discontinuities in ferromagnetic steel tubular products (Note 1) of uniform cross section, such as seamless and welded tubing. While this method may be sensitive to subsurface discontinuities, it is not the primary method used to identify these types of discontinuities. A secondary method, such as Ultrasonic Testing, should be considered for assessment of these types of discontinuities.NOTE 1: The term “tube” or “tubular product” will be used to refer to both pipe and tubing.1.2 This practice is intended for use on tubular products having outside diameters from approximately 1/2 to 24 in. (12.7 to 610 mm) with wall thicknesses to 1/2 in. (12.7 mm). These techniques have been used for other sizes, however, and may be so specified upon contractual agreement between the purchaser and the supplier.1.3 This practice does not establish acceptance criteria; they must be specified by the using parties.1.4 Units—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.1.5 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.1.6 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.