Limitations on the halogen content of materials that contact austenitic stainless
steels during fabrication, testing, shipping, and storage should be considered.
Austenitic stainless steels are susceptible to corrosive/pitting attacks by
halogens. Types of materials that should be considered for halogen limits are
cleaning agents, labels, markers, coatings, lubricants, insulations, oils,
adhesives, sealants, gaskets, wrapping, packaging, and packing materials.
Corrosion testing of austenitic stainless steels and nickel-based alloys should be
considered for process services that cause intergranular attack. For example,
hot nitric and formic acids are process services that cause intergranular attack of
stainless steels and nickel-based alloys. ASTM A262 , Standard Practices for
Detecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels,
provides guidance in how to perform these type of tests.
For buried metallic structures, use of cathodic protection, external coatings,
reducing or eliminating corrosion concerns in corrosive soils. Cathodic protection
systems should be installed at the same time as the structure being protected
and activated as soon as feasible. Delays in installation and activation of a
cathodic protection system may lead to early corrosion problems.
Use of internal cathodic protection systems and/or coating of the inside of
metallic water storage tanks should be considered depending on water
corrosivity. Determination of water corrosivity (calcium and sodium content) is
recommended in order to make an adequate determination.
Possible microbiological-influenced corrosion (MIC) of piping systems conveying
natural waters or tanks containing natural waters should be considered. The
common type of organisms that cause MIC are sulfate-reducing and iron- and
manganese-reducing bacteria. Both ferrous and nonferrous metals can be
affected and may suffer pitting or under-deposit corrosion.
Dissimilar metal connections in certain environments may be prone to
accelerated corrosion (galvanic corrosion). Analysis of the process conditions,
including the external conditions and the particular metals in contact, should be
considered to avoid excessive corrosion of the materials.