TPi January 2017

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58 TUBE PRODUCTS INTERNATIONAL January 2017
Schoeller Werk GmbH & Co KG – Germany
Careful testing of control and
injection pipes
The offshore industry uses such pipes as hydraulic control
lines for safety valves as well as for pumping chemicals into
an oil reservoir. In this way, they support the entire extraction
process. The injection pipes make it possible for rig operators
to use chemicals in targeted fashion to liquefy the oil and thus
improve its flow properties.
During the complex manufacturing process, the pipes
undergo various tests in order to ensure the special quality
of the products before they are installed. Strips of metal are
welded with a longitudinal seam using the tungsten inert
gas (TIG) welding process and rolled into tubes. Apart from
the obligatory eddy current testing, the tubes subsequently
undergo an air under water (AUW or ‘bubble’) test. The tubes
are submerged in water and filled with air to a pressure of up
to 210 bars. A visual inspection is made along the entire length
of the tubes to check that they are airtight.
So that Schoeller Werk can supply its customers with the
required lengths of 15,000m and more, individual pipes are
orbitally welded together and an X-ray is made to check
that the orbital weld is airtight and free of any pores. Before
delivery to customers, Schoeller Werk also subjects the
control and injection pipes to a hydraulic test. This involves
filling the finished coils with hydraulic fluid and subjecting
them to pressures of up to 2,500 bars to simulate the extreme
conditions sometimes experienced in offshore work.
Service offering supplements
manufacturing skill
Apart from pure manufacture of pipes, Schoeller Werk offers
its customers from the offshore industry a comprehensive
service package that includes, for example, encapsulation
of pipes with plastic sheathing in so-called flat packs. This
means that bundles of pipes can be attached to the extraction
tubes and protected from buckling and squashing.
Other services include flushing and filling of pipes. Here, the
insides of the pipes are flushed with hydraulic fluid until the
fluid reaches the specified ISO or SAE purity classification.
The fluid filtered in this way can remain in the pipes if the
customer requires, meaning that users obtain a product that
is ready to use. It is also possible to equip the pipe bundles
with electrical wiring or stainless steel support cables. Thanks
to the smooth internal surface, plug-drawn pipes are also
suitable for use as ducting for optical fibre cables transmitting
signals using light.
Offshore – a global market
In its work with the offshore industry, Schoeller Werk has
joined an international market. Apart from Norway and Great
Britain around the North Sea in Europe, Russia, Saudi Arabia,
UAE, Africa, Asia, Australia and South America all count
among the key target regions for use of the Schoeller control-
line and chemical-injection pipes.
Photo credit: Schoeller Werk
TIG orbital weld from inside: in order to supply lengths of
15,000m and more, individual pipes are orbitally welded together
Schoeller Werk’s service
package includes ‘flat
packs’, in which pipes are
sheathed in plastic
Injection pipes allow
chemicals to be used in
the extraction process
in targeted fashion to
liquefy the oil