The weld defect acceptance/rejection criteria are given in Chapter VI (Inspection, Examination, and Testing) of the ASME B31.1 – 2022 Power Piping Code.
Chapter VI of ASME B31.1 contains the qualification of NDE Personnel and the acceptance/rejection criteria for the weld defects by the following examination methods;
- Visual Examination (Para 136.4.2)
- Magnetic Particle Examination (Para 136.4.3)
- Liquid Penetrant Examination (Para 136.4.4)
- Radiography (Para 136.4.5)
- Ultrasonic Examination (Para 136.4.6)
- In-Process Examination (Para 136.4.7)
Weld defect acceptance/rejection criteria for visual Inspection :
The following indications are unacceptable as per ASME B31.1;
(1) Cracks — external surface.
(2) Lack of fusion on the surface.
(3) Incomplete penetration (applicable only when the inside surface is accessible).
(4) Weld reinforcement more than specified in the below table.
| Reinforcement of Girth and Longitudinal Butt Welds Summary of Table 127.4.2-1 | ||
| Thickness of Base Metal (T) | Maximum Thickness of Reinforcement for Design Temperature | |
| > 400°C (750°F) | ≤ 400°C (750°F) | |
| T ≤ 3 mm (1/8 in.) | 1.5 mm (1∕16 in.) | 2.5 mm (3∕32 in.) |
| 3 mm < T ≤ 5 mm (1∕8 in. < T ≤ 3∕16 in.) | 1.5 mm (1∕16 in.) | 3 mm (1∕8 in.) |
| 5 mm < T ≤ 13 mm (3/16 in. < T ≤ 1/2 in.) | 1.5 mm (1∕16 in.) | 4 mm (5∕32 in.) |
| 13 mm < T ≤ 25 mm (1/2 in. < T ≤ 1 in.) | 2.5 mm (3∕32 in.) | 5 mm (3∕16 in.) |
| 25 mm < T ≤ 50 mm (1 in. < T ≤ 2 in.) | 3 mm (1∕8 in.) | 6 mm (1∕4 in.) |
| T > 50 mm (2 in.) | 4 mm (5∕32 in.) | 6 mm (1∕4 in.) or 1/8 X width of weld whichever is greater |
(5) Undercut — Greater than 0.8 mm (1∕32 in.) deep, or if it exceeds the minimum required section thickness.
(6) Undercut on the surface of longitudinal butt welds
(7) Any other linear indications: Greater than 5mm (3∕16 in.) in length
(8) Surface porosity with rounded indications having dimensions greater than 3∕16 in. (5 mm) or four or more rounded indications separated by 1∕16 in. (1.5 mm) or less edge to edge in any direction.
(9) Arc strikes outside of the weld joint.
To know the acceptance criteria as per ASME Se9ction VIII Divison 1, Please click here.