Define the expected environmental conditions. Likely conditions to be
considered are embedment in soil or concrete, exposure to corrosive
atmospheres, use of thermal insulation, or attachment of electrical or steam-heat
Determine the need for material decontamination if the process service is
radioactive. Consideration should be included for enhanced surface finishes or
materials suitable for decontamination solutions.
Identify any historical materials documenting performance experience with similar
process streams and operating conditions. Successful past usage may indicate
suitable service, but careful comparison of the process conditions should be
Welding, Fabrication, Examination, and Testing . Fabrication processes, including
welding, forming (hot and cold), bending, threading, etc., should be controlled or
restricted based on the type of material used and the intended process service. The
following factors should be addressed:
Certain metallic materials may be susceptible to cracking during or following
welding. For example, aluminum bronzes and some aluminum alloys may suffer
air-hardenable and may need elevated preheat temperatures to avoid weld-metal
and heat-affected-zone cracking. It is important to distinguish between weld-
deposit cracking and heat-affected zone or base-metal cracking.
Some process services may require special heat treatments to reduce the risks
of stress-corrosion cracking. For example, a heat treatment may be required for
carbon-steel welds and cold bends in carbon steel exposed to caustics,
hydrogen sulfide, or amines.
Welding, hot forming, and heat treatment operations on certain materials may
degrade their corrosion resistance. Austenitic stainless steels and some nickel
alloys are examples of materials that can become susceptible to stress-corrosion
cracking in certain environments as a result of these operations. Limitations and
controls on welding and hot forming operations may be needed. Additionally,
special heat treatment may be required to prevent stress-corrosion cracking.