Page 473 - Pipeline Pigging Technology

Pipeline Pigging Technology

Fig.2. Slippage of product past a spheroid of varying size.
of 0.02-0.04% of the total volume displaced. Thus the 'flow back'
from front to rear of a properly-sized spheroid is minimized, but it
can never be eliminated".

It should be pointed out that the bore of a meter prover cannot be
compared to the surface roughness of an average pipeline, and oversizing a
sphere by 1% in a pipeline would simply result in unnecessary wear. It is now
generally accepted that spheres should be sized to the line ID.
Spheres were first used in multi-phase pipelines in 1958[2], and at about
the same time as Barrett was doing his work (1959), David W.Bean and
H.Norman Eagleton of Colorado Interstate Gas Co did some studies [3] on the
use of spheres for the control of liquid holdup in an 8-in multi-phase pipeline.
In 1963, Natural Gas Pipeline Co of America conducted tests using spheres
to control liquid holdup on a 13-mile section of 10-in pipeline. These
experiments formed the basis for a mathematical model designed to predict
the performance of multi-phase pipelines, which was developed in 1964 by
Alvis E.McDonald and Ovid Baker of Socony Mobil Oil Co Inc[2].
For reasons which are not apparent little, if any, further research seems to
have been done for another 14 years. Then, in 1978, Kara et al of Nippon
Kokan KK published a paper[4] which described their experiments using
spheres in a 4-in, 1300-m test line to determine the pressure drop for different
products when transported through a pipeline, separated by spheres. Among

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