1、 General requirements for radiographic testing personnel
1) Personnel engaged in radiation testing should receive training on radiation safety knowledge and obtain a radiation worker certificate before taking up their positions.
2) The uncorrected or corrected near and far visual acuity of X-ray testing personnel should not be less than 5.0 (with a decimal record value of 1.0), and the testing method should comply with the provisions of GB11533.
3) It is worth noting that personnel engaged in film evaluation should have their vision checked once a year.
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2、 General requirements for radiographic testing equipment
1) Viewing lamp
a) The maximum brightness of the viewing lamp should meet the requirements for film evaluation.
b) The main performance indicators of film viewing lamps, in addition to brightness, include: uniformity of brightness, shell temperature, noise, insulation degree, etc., which should meet the standard requirements.
When the blackness within the film evaluation range is ≤ 2.5, the brightness of the viewing lamp should not be less than 9400cd/m ²、 When the blackness within the film evaluation range is 2.5 ＜ D ≤ 4.0, the brightness of the viewing lamp should not be less than 100000cd/m ²。
2) Blackness meter
a) The maximum blackness that can be measured by the blackness meter should not be less than 4.5, and the error of the measured value should not exceed ± 0.05.
b) The blackness meter should be calibrated at least once every 6 months. The standard blackness film used for calibrating the blackness meter must be within its validity period and approved by the metrology department (2 years). Newly purchased standard blackness films are also allowed as long as they are within their validity period.
3) Intensifying screen
a) Lead screen intensifying screen is used for X-ray photography and Ir-192 ray source.
b) The thickness of the front and rear screens of the lead screen intensifying screen for Ir-192 radiation source should not be less than 0.1mm.
c) The thickness of the front and rear screens can be the same or different.
4) Image quality indicator
a) The quality of the negative image is measured using a linear image quality indicator. The model and specifications of linear image quality indicators should comply with the provisions of JB/T7902. The wire diameter, wire number, and other contents not included in JB/T7902 should comply with the relevant provisions of HB7684.
b) The material of the image quality indicator can be carbon steel or austenitic stainless steel.
3、 Surface requirements and timing of radiographic testing
1) Before radiographic testing, the surface of the butt welded joint should undergo visual inspection and be qualified. The irregular state of the surface on the negative film should not obscure or interfere with the defect image, otherwise the surface should be appropriately trimmed.
2) To prevent delayed crack tendency, radiographic testing should be conducted 24 hours after welding is completed.
4、 Radiation Protection for Radiographic Testing
1) When conducting X-ray testing on site, control areas and management areas should be designated and warning signs should be set up in accordance with GB16357. Testing personnel should wear personal dosimeters and carry dose alarms.
2) Conduct on-site γ During radiographic testing, control and supervision areas should be designated and warning signs should be set up in accordance with GB18465. During testing operations, radiation levels should be measured around the boundaries of the control area. Testing personnel should wear personal dosimeters and carry dose alarms.
5、 Radiographic testing and radiographic arrangement
1) Choose the center method and the double wall single shadow method for transparency.
2) During radiographic examination, the center of the ray beam should generally point vertically towards the center of the radiographic area. If necessary, a direction that is conducive to detecting defects can also be selected for radiographic examination.