ISO 10893-7:2019 Non-destructive testing of steel tubes – Part 7: Digital radiographic testing of the weld seam of welded steel tubes for the detection of imperfections.
4 General requirements
4.1 Unless otherwise specified by the product standard or agreed on by the manufacturer and the purchaser, a radiographic inspection shall be carried out on welded tubes after completion of all the primary manufacturing process operations (rolling, heat treating, cold and hot working, sizing and primary straightening, etc.).
4.2 This inspection shall be carried out by trained operators who are certified (e.g. Iso 9712) or qualified (e.g. ISO 11484 or ASNT SNT-TC-1A), and supervised by competent personnel nominated by the manufacturer. In the case of third-party inspection, this shall be agreed on between the manufacturer and the purchaser.
The operating authorization issued by the employer shall be according to a written procedure. Nondestructive testing (NDT) operations shall be authorized by a level 3 NDT individual approved by the employer.
NOTE The definitions of levels 1, 2 and 3 can be found in the appropriate standards, e.g. ISO 9712 and ISO 11484.
4.3 The tubes under test shall be sufficiently straight and free of foreign matter as to ensure the validity of the test. The surfaces of the weld seam and adjacent parent metal shall be sufficiently free of such foreign matter and surface irregularities, which would interfere with the interpretation of the radiographs.
Surface grinding is permitted in order to achieve an acceptable surface finish.
4.4 In cases where the weld reinforcement is removed, markers, usually in the form of lead arrows, shall be placed on each side of the weld such that its position can be identified on the radiographic image. Alternatively, an integrated automatic positioning system maybe used to identify the position of the weld.
4.5 Identification symbols, usually in the form of lead letters, shall be placed on each section of the weld seam radiograph such that the projection of these symbols appears in each radiographic image to ensure unequivocal identification of the section. Alternatively, an integrated automatic positioning system may be used to identify the position of each radiographic image along the pipe weld.
4.6 Markings shall be displayed on the recorded radiographic images to provide reference points for the accurate relocation of the position of each radiograph. Alternatively, the automated measured image position may be displayed on the digital image viewing screen by software for accurate position relocation.
4.7 When the detector size is smaller than the applicable weld length, the pipe or the detector shall move into start-stop mode and digital radiographs shall be taken when the pipe is not moving.
WARNING — Exposure of any part of the human body to X-rays or gamma-rays can be highly injurious to health. Wherever X-ray equipment or radioactive sources are in use, appropriate safety measures shall be applied.
Local, national or international safety precautions when using ionizing radiation shall be strictly applied.
5 Test equipment
The following digital imaging methods can be used in replacement of radiographic film:
a) CR with storage phosphor imaging plates (e.g. EN 14784-1 and EN 14784-2);
b) radiology with DDAs (e.g. ASTM E2597-07 and ASTM E2698).ISO 10893-7 pdf download.