when required by the contract or purchase order, the third party inspector witnesses low pressure air test and pays attention to the following points:
• Specialized testing of seats, the seals, by-passes, etc., may be required by purchase order.
• A minimum of 2 gauges with correct working ranges are used. The calibration of the gauges are checked.
Similarly, If the third party inspector is not in the hold or witness point in the ITP for this inspection stage, then he/she will review the valve manufacturer quality control report in his/her coming visit or on the final inspection day.