+1 vote

Considerations when designing the pigging system

asked Sep 3, 2014 in Piping by Normandy (21,040 points)

See pig trap safe orientation in another post.

2 Answers

+1 vote
answered Sep 3, 2014 by Normandy (21,040 points)

When designing the pigging requirements, the design should be based on type and size of pigs, as well as space restraints.  Consideration should be given to the following points:

  • Construction
  • Commissioning
  • Normal operation
  • Drainage and spillage
  • General safety and human factors (i.e., equipment height, location, accessibility, etc.)
  • Future requirements
  • Contractual requirements (if applicable)
  • Space should be provided for pig storage, when applicable
  • Sour service material selection should be in accordance with NACE MR0175
  • Piping should be designed and fabricated in accordance with ASME B31.3, ASME B31.4, ASME B31.8, API RP 14E, API SPEC 6D
  • The pig storage space design should provide sufficient room to allow safe lifting and handling of pigs (possibly by more than one person depending on pig weight) so that operators can lift the pigs near the body and without twisting
  • Sufficient space should be provided around the launcher/receiver traps to safely handle, load, and unload pigs into and from the launcher/receiver traps
  • Gauges, displays, etc. should be arranged appropriately for their sequence of use
  • Controls and gauges/displays should be located appropriately with respect to each other
  • Gauges/displays should be located so they can be seen clearly from the operator's normal working position(s) without the operator having to assume unsafe, awkward, or uncomfortable body positions
  • Controls should be located so they can be operated without the operator having to assume unsafe, awkward, or uncomfortable body positions
0 votes
answered Sep 4, 2014 by ekwuemesam (3,660 points)

Pig traps should be designed to be horizontal and for bi-directional flow. Vertical receiving traps have proven to be of limited success and should not be considered except in smaller sizes.

The followings should be considered when developing the pigging system design:

  • Pig sizing
  • Hydrostatic test
  • Scale and/or wax removal
  • Solids/debris removal
  • Condensate removal
  • Pipeline internal inspection
  • Dewatering
  • Drying
  • Geometric survey
  • Pipe defect survey
  • Product segregation
  • Inhibitor batching