TPT January 2008

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Coating, Jacketing & Galvanizing Technology
99 January 2008 ›
The work involved was
especially complex as
welding can cause material
shrinkage and distortion.
Because the overlay cladding
process requires vessels
to go through two welding
cycles, there were risks that
needed to be assessed and
addressed.
The Arc Energy welding and
fabrication teams therefore
needed to take considerable
care, both with the initial
setup and the welding
sequences, to ensure that allowances
were made for distortion. It was essential
that the customer received the vessel to
the exact specification ordered.
A second contract won by Arc involved
cladding four very large elbows as part of a
bigger project for Langfields Ltd, one of the
UK’s leading component fabricators. The
project at Shell’s Stanlow Refinery required
overlaying four 36" carbon steel elbows
with stainless steel.
Shell’s senior welding engineer, Mr Wayne
Griffiths, states “The technical skills
and knowledge of welding procedures
required were so demanding that not many
companies can, or even want to, handle
this type of work. Arc Energy Resources
were able to ship the elbows to their
factory in Gloucestershire for weld overlay
cladding.”
Elbows are always difficult to handle
but to accommodate the unusually large
diameters for this project Arc Energy also
needed to design and build two special
jigs.
To meet the tight delivery schedule both
workstations operated 24 hours a day for
the duration of the contract. In addition,
Arc Energy was responsible for proving
the quality of its cladding prior to delivery,
by 100 per cent non-destructive testing.
Arc Energy’s third big contract involved the
corrosion-proof cladding of an 8.65m-long,
16" diameter superduplex riser for Mardale,
a leading supplier of pipeline packages for
the oil and gas industries.
The pipe is destined for a sour oil reservoir
located approximately 10km offshore
in the Gulf of Suez. Oil and gas from
the field will initially be produced from a
single, unmanned nine-slot platform with
a 16" multiphase pipeline. The riser is a
vital component, connecting with onshore
facilities.
Because media temperatures of 120ºC in
the splash zone create a very corrosive
environment, the project required Arc
Energy to fully clad the riser externally
using 16 plates of 3mm alloy 59. The
new procedures had to be qualified in
accordance with ASME IX and other
international standards. The test welds
and subsequent mechanical testing was
witnessed by independent inspectors.
Following completion of the seal welding,
the cladding was subjected to 100 per
cent DPI followed by a pressure test
using an inert gas at a pressure of 1 bar.
The pressure test was held for 15 minutes
minimum and the sealing weld was visually
examined to ensure that no leaks were
evident.
Arc Energy Resources – UK
Fax: +44 1453 823623
Email :
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