Mill Pressure Test and System Pressure Test

Hi There, What you mean of mill pressure test? Are both the pressure test carried out according to the requirements to assess the integrity of design made?

All design are make-up from assumptions based on (or "imaginations") mill operation, experiences, best practices, and parameters and safety factors and guidance from Codes and Standards. These Codes and Standards were written based on a lot of considerations, best practices, experiences, accessment study of type of testings and defects allowed, stresses etc etc. So we will not be able to justify and looking into the broader (or whole) picture of the whole integrity of the system if we think certain testing is not require as we feel or think logically, but there are a lot of considerations that we have not taken into considerations i.e. end-up like no base reference line to make such decision. In addition, the testing on system is to access the integrity and proof testing to compliance as desinged, how do we know the fabricated system meet the design requirements if not tested to requirements?

Mill pressure test is normally tests on operating conditions which they have not simulate the worse conditions that design have considered and therefore is not tested to the stage as required. No doubt the system tested with mill pressure test can run and operate as require for mill but this could have compromised a lot of safety factors and risks and may not handled circumstances when the worse conditiones appear. I don't think the designer is confident to certified and guarantee on the intergity of the system.

If we considered the production of pipe as an example, there is a mill pressure test must be carried out for each pipe -or a sample from each group- inside the mill for certain pressure for a few seconds, governed by the related Codes and Standards. And a mill pressure test or certificate is issued.

For system pressure test, it is the pressure test carried out after completion of welding, fabrication and erection of the piping system under another certain pressures and durations, in according to another Codes and Standards related to fabrication and erection. And a system pressure test certificte is issued.

Please differentiate between pipe & piping.