Safety and compliance are priorities for the design and operation of pipeline pig launchers and receivers, also known as traps. During design, different codes and standards can be applied depending on the product that will be transported and where the equipment will be located. Because of code interpretation, an operator or equipment provider may over or under design the equipment for their pipeline.

This paper focuses on the codes that influence the materials and designs of pipeline traps, including the transitions from one design code to another, so called “spec breaks”. The spec break is the interface at the connecting mainline valve and hence this can permit the use of a pipeline code versus a pressure vessel code. Such spec break designs can result in designs that are simpler, easier to acquire material, have less lead time and lower cost.

In addition, this paper will discuss the lengths of traps, reducer types and closure integration, flanged or welded. The codes and standards that are discussed include ASME BPVC Section VIII, ASME B31.3, B31.4, B31.8, API 5L and CSA Z662.