The previous sections deal with inspection and testing during the fabrication of pressure vessels (including heat exchangers), embracing dimensional control, radiography, ultrasonics, magnetic and dye penetrant crack detection, and final testing. It is therefore necessary for the fabricator to have in operation an overall quality program, run by qualified and experienced personnel, which has been approved by an independent organization.

In the United States the organization concerned with the approval of companies for particular fabrications is the American Society of Mechanical Engineers (ASME) through its boiler and pressure code. This organization will approve fabricating companies outside the United States as well as American companies.

The system involves the submission of a quality control manual by the fabricator, which is reviewed, together with an audit of the company’s facility. Registered fabricators are authorized to construct fabrications to the appropriate code and stamp their vessels with the code stamp.

Similar schemes are in existence in other countries; for example, in the United Kingdom the approved scheme is operated by the Pressure Vessel Quality Assurance Board (PVQAB). In all cases the pressure vessel fabricator is overseen by an authorized inspector, who must be suitably qualified. Certain authorities will only allow pressure vessels to be installed and operated in their country if they have conformed with the above systems.

Total quality systems are all basically similar and in general must conform to the following requirements, which are summarized in the company’s quality manual.