scope:

Thick wall pressure vessels are the heart of hydroprocessing units in today's modern petroleum refinery. These large reactor vessels range up to over 1000 tons in weight and some have wall thickness of about 1241-1. Similar reactors, even larger in size. are now being proposed for processing synthetic fuels derived from coal, shale, and tar sands . Low alloy steels are required for resistance to internal attack by hydrogen that is absorbed in the hydroproprocess. Low alloy steels are required for resistance to internal attack by hydrogen that is absorbed in the hydroproprocess environment. The leanest alloy offering suitable resistance in most hydroprocessing environments is the 21/4% chromium 1% molybdenum composition which also has attractive mechanical properties and responds to heat treatment in very heavy sections.