Page 404 - Pipeline Pigging Technology

Pigging through Yfittings

PIGGING CHARACTERISTICS OF
CONSTRUCTION, PRODUCTION AND

INSPECTION PIGS THROUGH PIGGABLE

WYE FITTINGS

RESULTS OF pigging tests are presented for various construction, produc-
tion and inspection pigs which demonstrate their pigging characteristics
while passing through a lOin x lOin x lOin piggable wye fitting. Detailed
results are presented for inflatable and soluble spheres, a dual-diameter
scraper pig, squeegee(cup-type) pig, foam pigs, dual-diameter gauging pig
and an intelligent pig. Details of the test facility, procedures, and data-
reduction techniques are also presented and discussed.

INTRODUCTION

Piggable wye fittings used for high-pressure, underwater pipeline applica-
tions were introduced in the North Sea nearly ten years ago. Since then, other
areas such as the Gulf of Mexico, Adriatic Sea and Middle East have also seen
applications. The main reason for using piggable wye fittings is to allow lateral
connections to trunklines that can be pigged from either the lateral side or
through the trunkline.
There are several reasons for designing a piggable lateral connection. For
oil pipeline applications, the main interest has been to allow scraper pigs to
be used where accumulated paraffin deposits can lead to plugging of the
lateral pipeline. For gas or two-phase liquid/gas transmission applications, the
interest is usually to allow running pigs for removal of liquids that increase
pressure losses or cause internal corrosion. There is also a growing interest in
the use of inspection pigs that can be used to examine the lateral pipeline.
Prior to the introduction of piggable wye fittings, on many gathering
systems it was necessary to bring the pipeline to a platform, up a riser and into

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