Page 386 - Pipeline Pigging Technology

Recent advances in piggable Y design

Pipelines Operator Product Size Status Pressure
(inches) (psig)

Piper to MCP-01 Occidental Gas 18 Shutdown 2612

Ula and Gyda to
Ekofisk Statoil Oil 20 Operational 2026

Gyda to Ula wye Statoil Oil 20 Operational 2026

Veslefrikk and
Oseberg C to Statoil Oil 16 Operational 1682
Oseberg A
Beryl and Brae
to St Fergus Mobil Gas 30 Planned 2500

Piper and
Claymore to Occidental Oil 30 Planned 2160
Flotta

Bruce and Frigg
toMCPOl Total Gas 32 Planned 2160

Table 1. North Sea wye junctions.
single forged block with machined straight bores of the same diameter as the
pipeline at a 30° included angle. It was pigged during commissioning but
rarely during operation due to the high quality of the gas. The spare branch
was never connected up, and the pipeline and wye are now shut down.
However, Occidental is to install a further wye of a similar design as part of
the Piper redevelopment. This will be a 30-in block with straight bores at a 22°
angle. It will replace the Claymore tee junction.
In 1986 Statoil installed a wye in the 20-in oil line from Ula to Ekofisk, 4km
from Ula. Illustrated in Fig.3, the bores are curved and enlarged with a 30°
included angle. The enlargement of the bores reduces the drag on the pigs as

367