Inspection by an outside body in no way relieves the manufacturer of responsibility to the purchaser. The inspection stages should be varied to suit the design and materials of the heat exchanger, but the following are the main inspection stages (see also particular design and construction code for specific and mandatory requirements, which will of course have to be complied with):

1. Identification of material against material certificates.
2. Checking that the weld procedures and welder approvals have been authenticated by an acceptable inspection body or qualify as necessary. This is also applicable to nondestructive testing procedures and approvals.
3. Examination of part when cut to size and shaped with edges prepared for welding. At this examination attention should be given to the plate edges to ensure that they are free from flaws, cracks, laminations, and slag inclusions.
4. Examination during welding to ensure that the correct procedures are being used and that the parts are within the tolerance specified in the design code.
5. Check to ensure that heat treatments have been carried out as required.
6. Examination of completed welding and witnessing the nondestructive testing where applicable.
7. Examination of tube plates with tube hotes drilled. At this stage consideration should be given to the nondestructive testing of the tube plates to ensure that they are free from any unacceptable laminations.
8. Examination of tube bundle assembled in tube plate(s).
9. Witnessing pressure tests and leak tests where applicable.
10. Final examination and checking of exchanger dimensionally against the drawing.
11. Checking marking and stamping of the exchanger and examination of final documentation.