The primary purpose of this recommended practice (RP) is to summarize the basic body of knowledge that the source inspector typically needs to know to perform as a source inspector for fixed equipment. A secondary purpose is to assist candidates intending to take the API Source Inspection Examination to become certified source inspectors. This RP outlines the fundamentals of source inspection and may be useful to all personnel conducting such activities to perform their jobs in a competent and ethical manner. This RP covers the process of specifying the necessary quality surveillance of materials, equipment, and fabrications being supplied for use in the oil, petrochemical, and gas Industry, including upstream, midstream, and downstream segments. This RP may be used as the basis for providing a systematic approach to risk-based source inspection in order to provide confidence that materials and equipment being purchased meet the minimum requirements as specified in the project documents and contractual agreements. The activities outlined in this RP are not intended to replace the manufacturer's/fabricator's own quality system, but rather are meant to guide SIs acting on behalf of purchaser to determine whether manufacturers'/fabricators' own quality systems have functioned appropriately, such that the purchased equipment and materials will meet contractual agreements.