Those pipes need to be inspected using radiographic testing

Check the relevant regulations for pressure pipelines!

Refer to the relevant provisions in GB150 and the Safety Technical Supervision and Inspection Regulations for Pressure Vessels.

In accordance with the provisions of the **standard GB 50235-97 \"Code for Construction and Acceptance of Industrial Metal Piping Projects\" of the People’s Republic of China, radiographic inspection and ultrasonic inspection of pipelines shall comply with the following requirements: 1. The internal quality of pipeline welds shall be inspected by radiography or ultrasonic testing as specified in the design documents. The methods and quality grading criteria for radiographic inspection and ultrasonic inspection shall comply with the provisions of the current **standard, \"Code for Construction and Acceptance of Welded Works on Field Equipment and Industrial Pipelines\". Radiographic inspection or ultrasonic inspection of the 2-pipe welds should be carried out promptly. During sampling inspections, random checks should be conducted on the welds welded by each welder at a specified ratio, and the inspection locations shall be determined jointly by the quality inspection personnel from the construction unit and the employer. 3 The number of radiographic inspections for pipeline welds shall comply with the following provisions: 3.1 The following pipeline welds shall undergo 100% radiographic inspection, and their quality shall not be lower than Grade II: (1) Pipelines transporting highly toxic fluids ； (2) Pipelines for transporting flammable or toxic fluids with a design pressure of 10 MPa or more, or a design pressure of 4 MPa or more along with a design temperature of 400°C or more ； (3) Pipelines for non-flammable and non-toxic fluids with a design pressure of 10 MPa or higher and a design temperature of 400 °C or higher ； (4) Low-temperature pipelines with a design temperature of less than –29°C. (5) Other pipes for which the design documents require 100% radiographic inspection. 3.2 For welds of non-flammable fluid pipelines and non-toxic fluid pipelines with a design pressure of less than or equal to 1 MPa and a design temperature of less than 400°C, radiographic inspection may be omitted. 3.3 Other pipelines shall be subject to sampled radiographic inspection, with a sampling rate of not less than 5%, and their quality shall not be lower than Grade III. The sampling ratio and quality grade shall meet the requirements of the design documents. 4 With the consent of the construction unit, ultrasonic testing may be used in place of radiographic testing for the inspection of pipeline welds, and the number of inspections shall be the same as that for radiographic testing. For the 5 pairs of welds for which no internal quality inspection is required, the quality inspectors shall conduct visual inspections on all of them in accordance with the provisions of this specification. 6 When inspections reveal that the weld defects exceed those specified in the design documents and these specifications, repair must be carried out. After the welds are repaired, they shall be inspected using the methods specified originally. 7 When no weld defects requiring repair are found in the sampling inspection, the batch of welds represented by that sample shall be considered to be fully qualified ； When sampling inspections reveal weld defects that require repair, in addition to repairing such welds, further inspection shall be carried out using the original specified methods as follows: 7.1 For each defective weld found, two additional welds from the same batch welded by that welder shall be inspected. 7.2 When both of these welds are qualified, the batch of welds represented by this inspection shall be considered qualified. 7.3 When these two welds fail the inspection again, each failed weld shall be followed by two additional welds from the same batch performed by the same welder. 7.4 When all the welds re-inspected are qualified, it can be considered that the batch of welds represented by this inspection is qualified. 7.5 If failure is detected again upon re-inspection, all welds welded by that welder in the same batch shall be inspected. 8 For welds that require heat treatment, the hardness of the welds and the heat-affected zones shall be measured after heat treatment, and these hardness values must comply with the specifications stated in the design documents. When the design documents do not specify otherwise, carbon steel should not exceed 120% of the hardness of the base material ； The hardness of alloy steel should not exceed 125% of that of the base material. The number of inspections should be no less than 10% of the total number of heat-treated welds. 9 For pipe welds that require heat treatment, a “Heat Treatment Report” shall be filled out in the format specified in these specifications.

Do liquid nitrogen pipelines with a DN15 size and a design pressure of 0.5 MPa require flaw detection?

Simply put, it needs to be done in every area where there are welds

The one from 97 has expired; there’s no such regulation in the one from 2010