Special Material Requirements for Refinery Equipment

The use of austenitic stainless steel should be kept to a minimum. When the use of such a material cannot be avoided and where there is danger of transgranular stress corrosion cracking, the use of higher alloy materials such as stabilized Incoloys or ferritic stainless steel such as Type 444 (18 Cr-2 Mo) should be considered. 

For parts to be welded, including tank plates and structural steel, no bottom or side air or enriched air-blown converter steels should be used. Oxygen-blown converter steel may be used only below the creep temperature range. 

The use of copper-based alloys in direct contact streams in which ammonia acetylene or its homologs may be present is prohibited. 

Carbon content and carbon eqnivalent, based on (C + Mn)/6 for any plain carbon or carbon manganese steel that is to be joined by welding, should not exceed 0.25% and 0.41%, respectively. 

In cases where the above requirements are not met, welding procedure qualification tests in accordance with applicable codes should be performed, and welding procedures for the portions subjected to the tests should be submitted for agreement separately. 

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