Regarding the issue of the proportion of fittings for regular inspection of pressure pipelines.
Thread Content
During regular inspections, how is the base figure for the sampling rate of pipe fittings calculated? For example, if there are 30 elbows and 20 tees, and the sampling rate is 20%, then (1) 20% of each type of fitting is sampled, which means 30*20% = 6 elbows. ； The number of tee joints is 20*20% = 4. (2) The total number of elbows and tees to be drawn is (30+20)*20% = 10; in this case, there might be 10 elbows and 0 tees ； 9 elbows, 1 tee, etc. Which of the two algorithms mentioned above is correct?
Of course, for the first option, in addition to having a sampling ratio, it is also necessary to cover various types