Most companies have a detailed general specification for the construction of pressure vessels, which defines the overall quality of fabrication required and addresses specific items such as:
• Code compliance
• Design conditions and materials
• Design details
• Vessel design and tolerances
• Vessel connections (nozzle schedules)
• Vessel internals
• Ladders, cages, platforms, and stairs
• Vessel supports and lifting lugs
• Insulation supports
• Shop drawings
• Fabrication
• General
• Welding
• Painting
• Inspection and testing
• Identification stamping
• Drawings, final reports, and data sheets
• Preparation for shipment
A copy of this specification is normally attached to a bid request form, which includes a pressure vessel specification sheet such as the one shown in Figure 12-4. This sheet contains schematic vessel drawings and pertinent specifications and thus defines the vessel in enough detail so the manufacturer can quote a price and so the operator can be sure that all quotes represent comparable quality. The vessel connections (nozzle schedules) are developed from mechanical flow diagrams. It is not necessary for the bidder to know the location of the nozzles to submit a quote or even to order material.
