Using the piping inspection RAGAGEP API 570, one of the first steps in our piping inspections/testing is to establish the “Class” our piping fits into. In most cases, I advise my clients to classify their PSM/RMP-covered piping as Class 1. However, there is a possibility that some flammable liquid piping could be classified in a lower class (although I would never recommend it). This came up with a newly built process, and I thought I would use their discussion as a teachable moment.
The argument was to classify their flammable liquids piping as Class 2 rather than Class 1. The differences between these classes can lead to significant reductions in inspection/testing frequency, which drives much of the debate. Had this been a small system/process (e.g., NOT covered under PSM), I would have agreed, as their flammable liquid clearly met the Class 2 definition.
API 570 states the following regarding how we establish the piping class, which then dictates the frequency and extent of inspections.