It is essential that wrought and cast fittings and valves that are normally purchased outside are subjected to the prescribed inspection and testing requirements, for on occasion tire documentation of these components and the relevant inspection has been overlooked with consequent delivery difficulties.

It is of considerable assistance to the inspection authority if the manufacturer sends copies of suborders to facilitate such inspections. Irrespective of the arrangements made for inspection, valves and fittings should be subjected to the necessary checks before fabricating or fitting into the heat exchanger. The degree of inspection is normally defined in the applicable construction standard.