Timing for Implementing Nondestructive Testing of High-Pressure Reactors

　　The specific timing for performing non-destructive testing on the welded joints of the high-pressure reactor assembly:

　　1. The weld joints of the high-pressure reactor shall undergo inspection for shape, dimensions, and appearance; only after passing these inspections can they proceed to non-destructive testing.

　　2. The welded end closure shall undergo nondestructive testing after forming. If nondestructive testing has already been performed before forming, then after forming, additional nondestructive testing must also be conducted on the transition zone from the arc to the straight edge segment.

　　3. Materials with a tendency toward delayed cracking shall undergo nondestructive testing at least 24 hours after welding is completed. Materials with a tendency toward reheat cracking shall undergo an additional nondestructive test following heat treatment.

　　4. For high-pressure reactors made of low-alloy steel with a minimum specified tensile strength of 540 MPa or higher, after testing, the welded joints shall also undergo non-destructive testing.

　　5. For high-pressure reactors assembled and welded on-site, before the pressure test, the weld joints shall undergo surface non-destructive testing in accordance with the relevant standards. After the pressure test, surface non-destructive testing shall be conducted again according to the applicable standards. If defects such as cracks exceeding the allowable limits are detected, supplementary inspections shall be carried out as specified in the standards. If the weld joints still fail to meet the requirements after these supplementary inspections, a full-surface non-destructive examination of the weld joints shall be performed.