What is a specification and why does an engineer need to write one before purchasing heat transfer equipment? A specification details the technical requirements for the equipment and, together with data sheets and drawings, forms an inquiry package to be sent to suitable vendors. Most equipment is covered by code and standard requirements; so, what should the specification contain over and above these requirements?

Engineers are increasingly concerned with not only more detailed client requirements and quality control but also package plant and skid-mounted units. Documentation and certification considerations now take up a large percentage of engineering time, especially for hazardous plant.

This section gives a brief introduction to some of the problems a contractor's engineer dealing with heat transfer equipment may face and suggests how the process of writing job specifications and assessing vendors' quotations should be handled. Typical checklists, by no means all-inclusive, are included.

Presentation of vendor bid analyses will differ from company to company. Obviously, it is useful to tabulate information on standard forms in order to compare bids. This not only assists in checking at the purchase order stage that the scope of the job is fully covered but also provides a record of exactly what was bought. Two typical bid analyses are given to illustrate this.

The terms contractor, client, and vendor are used throughout the section. A contractor will normally act on behalf of the client to design, engineer, and construct a plant. The client will normally be an end producer of (say) petrochemicals or power from that plant. The vendor will normally design and fabricate particular equipment, such as heat exchange equipment, for the plant. The term engineer is used in the text to denote the person responsible for the contractor's engineering.