This recommended practice (RP) provides recognized industry practices, requirements, and guidance for the installation, in-service inspection, and repair assessment of refractory lining installed into equipment that is used in general refinery services. Refinery equipment included in the scope of this standard includes, but may not be limited to, Fluid Solids Units—including Fluid Catalytic Cracker Units (FCCUs), Reforming Units, Fired Heaters, Incinerators, Sulfur Recovery Units, Flue Gas Ducts, Calciners, Steam-Methane Reformers (SMRs), Cracker Furnaces, Boilers, Hydrogen plant and transfer lines, and Flue Gas Stacks.

Inspection and quality control for design and installation of new, patch repair or replacement lining systems are covered in separate API documents, including:
• API Standard 936, Refractory Installation Quality Control—Inspection and Testing Monolithic Refractory Linings and Materials
• API Standard 975, Refractory Installation Quality Control—Inspection and Testing of Refractory Brick Systems and Materials
• API Standard 976, Refractory Installation Quality Control—Inspection and Testing of Fiber Linings and Material
Proper inspection and assessment of the refractory linings is essential to maintain equipment reliability, operating efficiency, personnel safety, and operational process safety.