NACE SP0170-2012

This standard practice provides mitigation methods to protect austenitic stainless steels and other austenitic alloys from PTA SCC that can occur during a shutdown of refinery equipment.

For the purposes of this standard, a shutdown includes the actual downtime period and the contiguous periods required to shut down and start up the equipment.

For the purposes of this standard, the term austenitic materials includes austenitic stainless steels and other austenitic alloys.

For the purposes of this standard, the term other austenitic alloys refers to those alloys of nickel, iron, and chromium that may be susceptible to PTA SCC.

For the purposes of this standard, the term purging is defined as a flow of inert gas (in this case dry nitrogen) to free the system of impurities (oxygen).