Page 189 - Pipeline Pigging Technology

Pipeline Pigging Technology

turbulence of the degreaser, the scouring action of the brush pigs, the
entrainment of the loosened material by the debris gel, the suspension of
particles in the degreaser, and the use of mechanical pigs and separator
gellypigs to displace material in the pipeline, all support the theory to use a
lower volume of degreaser.
4. Mechanical pigs: Enduro brush pigs - these are very aggressive cleaning
brush pigs. They comprise two doughnut-shaped brushes, which are self-
adjusting as they become worn, between two cups.
Poly pig (RCQ w/brushes - these foam pigs have a durable red plastic
coating in a criss-cross pattern, which contains straps of wire brushes, for light
brushing. These foam brush pigs help reduce the chances of a stuck pig, but
still provide a good seal and light brushing, if they do not deteriorate. The poly
pig with brushes was used between the first separator and debris gel slugs, to
provide some brushing action prior to the first debris gellypig, but without the
high risk associated with more rigid brush pigs.
Super pig cup pig - standard four-cup Super pigs and unicast five-cup pigs
comprised of polyurethane cups were used for efficient wiping, interfacing,
displacing and sealing, in various parts of the pig train. It was used behind the
degreaser, and as the final pig in the train to provide a good seal.
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2* poly pig - this is a very lightweight foam pig (21b/ft ), sometimes used
as an interface between gellypigs to help prevent intermingling, or in
conjunction with other mechanical pigs in an attempt to provide a better seal.
These are typically options for use in gellypig trains. It is also used to absorb
liquids during drying operations.
5. Nitrogen - was used to launch all mechanical and poly pigs, as well as a
pad of nitrogen at the front and rear of the train. The nitrogen was an added
safety precaution, since the trains were to be driven with air, and light
hydrocarbons existed in the pipeline.

EXECUTION

The gellypig services were performed in two distinct phases, as previously
discussed. Phase 1 began mixing gellypigs on 19th November, 1989. The train
was launched from the W.Alton meter station on 21 st November, and the pigs
were received at the Chantilly Station on 22nd November. All equipment was
moved from W.Alton to Auburn Station, to begin Phase 2.
Phase 2 began mixing gellypigs on 28th November. The train was launched
from Auburn Station on 30th November, and the pigs were received at
Curryville Junction on 2nd December.

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