The B31.3 Code contains requirements for piping typically found in petroleum refineries; chemical, pharmaceutical, textile, paper, semiconductor, and cryogenic plants; and related processing plants and terminals. This code prescribes requirements for materials and components, design, fabrication, assembly, erection, examination, inspection, and testing of piping.

This Code applies to piping for all fluids including:

• (1) raw, intermediate, and finished chemicals
• (2) petroleum products
• (3) gas, steam, air and water
• (4) fluidized solids
• (5) refrigerants
• (6) cryogenic fluids.
• Also included is piping which interconnects pieces or stages within a packaged equipment assembly.