Process piping refers to the piping systems (including pipes, tubing, fittings, flanges, valves, and pipe supports) typically found in petroleum refineries, chemical, pharmaceutical, textile, paper, semiconductor, and cryogenic plants, and related processing plants and terminals. Process piping is the focus of ASME B31.3-2016 – Process Piping, the third section of the ASME B31 Code.
The ASME B31.3-2016 – Process Piping standard prescribes guidelines for materials and components, design, fabrication, assembly, erection, examination, inspection, and testing of piping. The code is applicable to all types of fluids transferred in processing plants, such as raw, intermediate, and finished chemicals, petroleum products, gas, steam, air, and water, fluidized solids, refrigerants, and cryogenic fluids.
There have been a multitude of changes made to ASME B31.3-2016. Major changes to this latest edition include:
Severe Cyclic Conditions
- “Conditions applying to specific piping components or joints for which the owner or the designer determines that construction to better resist fatigue loading is warranted”. This revision includes guidance on designing piping under these conditions.
MPa Allowable Stresses
- Previously included in ASME B31.3 as information only, either MPa (megapascal) or ksi (kilopound per square inch) units may now be used for compliance with the Code.
- A new section has been added for expansion joints, as the standard now specifies the design of metallic bellows expansion joints, slip type expansion joints, and others. Expansion joints are also addressed in different pipe and leakage guidelines throughout the document.
Flange Joint Assembly
- The revision calls for assembly requirements for bolted flanged joints and flanged joint assembly qualifications to be considered in the engineering design.
Ultrasonic Examination Acceptance Criteria
- ASME B31.3-2016 specifies a transfer method for conducting the ultrasonic examination of welds and other materials in the piping system.
Category M Fluid Service Examination
- The definition for Category M Fluid Service has been revised.
Leak Testing of Instrument Connections
- Threaded joints and tubing joints now do not need to be leak tested in accordance with the ASME B31.3 leak test.
Leak Testing of Vacuum Systems
- Vacuum leak testing is included as an alternative to the internal pressure method.
Leak Testing of Insulated Systems
- The Code now allows some joints to be covered by insulation during leak testing.
Leak Testing of Assembled Piping
- Pipe and related components and assemblies can be tested either separately or as assembled piping.
Of course, these ten alterations are among the most major changes, but they do not encompass all of the adjustments made to the new revision. To assist users, the early pages of ASME B31.3-2016 – Process Piping list the location of each change made to the document.