API RP 581 - 3rd Ed.2016 - Add.2-2020 - Risk-Based Inspection Methodology

3-54 API RECOMMENDED PRACTICE 581
Table 4.7M—Leak Durations Based on Detection and Isolation Systems
Detection System
Rating
A
A
A
B
B
C
Isolation System
Rating
A
B
C
A or B
C
A, B, or C
Maximum Leak Duration,
ld
max
20 minutes for 6.4 mm leaks
10 minutes for 25 mm leaks
5 minutes for 102 mm leaks
30 minutes for 6.4 mm leaks
20 minutes for 25 mm leaks
10 minutes for 102 mm leaks
40 minutes for 6.4 mm leaks
30 minutes for 25 mm leaks
20 minutes for 102 mm leaks
40 minutes for 6.4 mm leaks
30 minutes for 25 mm leaks
20 minutes for 102 mm leaks
1 hour for 6.4 mm leaks
30 minutes for 25 mm leaks
20 minutes for 102 mm leaks
1 hour for 6.4 mm leaks
40 minutes for 25 mm leaks
20 minutes for 102 mm leaks