Page 469 - Pipeline Pigging Technology

Pipeline Pigging Technology

Although there is a growing awareness of the need for greater efficiency,
it is probable that if intelligent pigs had not been developed, this evolutionary
process would have continued. Intelligent pigs have highlighted the need for
more research and development into conventional pigging.
All intelligent pigs need a clean line for optimum performance, and this
requires the development of highlyxffective conventional pigs and pigging
programmes.
The results of an intelligent pig run often show that the pigs and/or
programmes which had been routinely used, were totally inadequate. It is
now accepted that regular, effective pigging, coupled with a sound inhibition
programme, is much cheaper than replacing a pipeline.
But what is effective pigging? At this moment, no-one knows. There are lots
of theories, but few, if any FACTS.
In most, if not all cases, pig manufacturers’ recommendations for optimum
performance are basedon “experience”, Normally, experience is perhaps the
best possible way of establishing performance parameters, but in this case it
should be remembered that it is not the manufacturers that have the
experience - but the operators .....
A certain amount of this operational experience is fed back to the
manufacturer, often in the form of complaints, but the majority is not. Indeed,
many operators regard the results of a pig run as confldential, and so very little
actual experience is shared. The manufacturers’ recommendations therefore
rely heavily on the limited amount of information which does filter back to
them, together with perhaps some very modest research or observations of
their own. This is clearly inadequate, and is the reason why the first step in any
study must be to make a concerted effort to gather as much experiential
information as possible before deciding on the R&D programmes that will be
required.
In December 1990, On-Stream Systems Ltd was contracted by CALtec Ltd,
a subsidiary of the BHR Group, to work with it in carrying out a detailed study
of the current state-of-the-art in conventional pipeline pigging. Apart from
being a valuable guide in its own right, this study will point to the areas in need
of a concerted R&D programme. It may also point to the form that such
research should take.
The study, which is funded by a consortium of major pipeline operators,
is scheduled for completion in July, 1991.
At this time it is impossible to tell which aspects of conventional pigging
will be found to be in need of a formal R&D programme, or what their order
of priority might be, but it is likely to include some or all of the following:
the effects of velocity, and determination of optimum pig speeds;
design of pigs capable of performing in widelydiffering diameters;

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