13.2 The following information is for the benefit of the user of this specification:
13.2.1 The reference standards defined in 13.8 are con ‘enient standards for standardization of nondestructive examination equipment. The dimensions of these standards should not he construed as the minimum size imperfection detectable by such equipment.
13.2.2 Ultrasonic examination can he performed to detect both longitudinally and transversely oriented discontinuities. It should be recognized that different techniques should be employed to detect differently oriented imperfections. The examination may not detect short, deep imperfection s.
13.2.3 The eddy current examination referenced in this specification has the capability to detect significant discontinuities. especially of the short abrupt type.
13.2.4 The flux leakage examination refelTed to in this specification is capable of detecting the presence and location of significant longitudinally or transversely oriented discontinuities. It should he recognized that different techniques should he employed to detect differently oriented imperfections.
13.2.5 The hydrostatic test of Section 12 has the capability to find imperfections of a size that permit the test fluid to leak through the pipe wall so that it may he either visually seen or detected by a loss of fluid pressure. This test may not detect very tight. through-wall imperfections, or imperfections that extend into the wall without complete penetration.
13.2.6 A purchaser interested in ascertaining the nature (type. size, location, and orientation) of discontinuitics that can be detected in the specific application of these examinations should discuss this with the manufacturer of the tubular products.
13.3 Time of Examination:
13.3.1 Nondestructive examination for specification acceptance shall be performed after all mechanical processing, heat treatments and straightening operations. This requirement does not preclude additional testing at earlier stages in the processing.
13.4 Surface Conditions:
13.4.1 All surfaces shall he clean and free of scale, dirt, grease, paint, or other foreign material that could interfere with interpretation of test results. The methods used for cleaning and preparing the surfaces for examination shall not be detrimental to the base metal or the surface finish.
13.4.2 Excessive surface roughness or deep scratches can produce signals that interfere with the test (see
13.5 Extent of Examination:
13.5.1 The relative motion of the pipe and the transducer(s), coil(s), or sensor(s) shall be such that the entire pipe surface is scanned, except for end effects as noted in
13.5.2 The existence of end effects is recognized, and the extent of such effects shall he determined by the manufacturer, and, if requested. shall be reported to the purchaser. Other nondestructive tests may be applied to the end areas, subject to agreement between the purchaser and the manufacturer.
13.6 Operator Qualifications — The test unit operator shall be certified in accordance with SNT-TC-1A, or an equivalent, recognized and documented standard.
13.7 Test Conditions:
13.7.1 For examination by the ultrasonic method, the minimum nominal transducer frequency shall be
2.25 MHz.
13.7.2 For eddy current testing. the excitation coil frequency shall be 10 kHz, or less.
13.8 Reference Standti rds:
13.8.1 Reference standards of convenient length shall be prepared from a length of pipe of the same grade, size (NPS or outside diameter and schedule or wall thickness). surface finish and heat treatment condition as the pipe to be examined.
13.8.2 For ultrasonic testing, the reference notches shall he any one of the three common notch shapes shown in Practice E 213, at the option of the manufacturer. The depth of the notch shall not exceed 1 2% of the specified nominal wall thickness of the pipe or 0.004 in. (0. 1 mm). whichever is greater. The length of the notch shall be at least twice the diameter of the transducer(s). The width of the notch shall not exceed the depth.
13.8.3 For eddy current testing, the reference standard shall contain, at the option of the manufacturer, any one of the following discontinuities: Drilled Hole — The reference standard shall contain three or more holes, equally spaced circumferentially around the pipe and longitudinally separated by a sufficient distance to allow distinct identification of the signal from each hole. The holes shall he drilled radially and completely through the pipe wall, with care being taken to avoid distortion of the pipe while drilling. The hole diameter shall vary with NPS as follows.