Contracting Engineer, Chicago Bridge & Iron Company, New York, N.Y.
Area Welding and QA Manager, Chicago Bridge & Iron Company, Houston, Tex.
Pages: 20 Published: Jan 1982
As energy demands steadily increase, industry will require a new generation of pressure vessels to expand the capacities of existing crude oil refineries and to establish synthetic fuels capabilities. These vessels will be a challenge to fabricators. The probable choice of 2¼Cr-1Mo steel will require special attention during fabrication to maintain metallurgical quality. Many of the vessels will be larger than ever; wall thicknesses of 250 to 410 mm (10 to 16 in.) and total weights of 1800 metric tons (2000 tons) and more will be realities. This may necessitate complete field assembly, including welding, nondestructive examination, and postweld heat treatment.
The sizes of the vessel are formidable, but the complexity of the projects is not new and the technology is available. Shop fabrication of components which are then shipped to the site is the typical approach. However, when site location or size of the pressure vessel prohibits transportation, extensive fabrication and complete assembly in the field is required. Lifting equipment can be tailored to the configuration of the vessel and the demands of the project. Heavy plates can be welded with various techniques that ensure good mechanical properties without sacrificing quality. Nondestructive examination (NDE), including radiography, is the same quality available in the shop. Postweld heat treatment (PWHT) can be accomplished in sections, or the entire structure can be insulated and stress relieved in a single operation.
Fabrication of the new generation of large pressure vessels is a natural extension of previous experience in field-assembled structures. The techniques and technology necessary to build quality vessels on schedule exist now.
pressure vessels, 2¼Cr-1Mo material, heavy wall thicknesses, field fabrications, preheat, postheat, automatic submerged arc welding, stainless steel overlay, nondestructive examination, machining, erection, postweld heat treatment
Paper ID: STP28419S