TPT July 2015

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Straightening
82 July 2015
New solution for mechanical
bonding of CRA lined pipes
CRA lined pipes or CRA clad pipes are
corrosion-resistant pipes consisting of
a corrosion-resistant inner pipe and a
carbon steel outer pipe that can withstand
internal and external pressure.
Potential applications for pipes with
CRA material are subsea pipelines
for sour gas and oil, water reinjection
systems, saltwater pipelines, and
process pipes in the chemical industry.
CRA lined pipes are mainly used as flow-
lines, riser pipelines, interfield pipelines
and water injection pipelines.
There are two methods of bonding
the CRA material to carbon steel:
metallurgical bond (CRA clad pipes) and
mechanical bond (CRA lined pipes).
The metallurgical bond between two
different metals (bonding of plates) is
achieved by hot rolling, co-extrusion,
weld overlay or explosive bonding. A
disadvantage is the limited number
of suppliers due to the demanding
and complex manufacturing process
of metallurgically bonding the plates,
which creates high costs.
Mechanical bonding between the
backing steel pipe and the CRA pipe
by use of spring back variation can be
performed by means of hydroforming or
by a full length pipe expander.
There is growing demand for CRA
lined pipe due to the fact that corrosive
conditions are expected to increase
as produced fluids contain higher
water cuts and greater concentrations
of H2S and CO2. In addition, these
increasingly corrosive products need to
be transported over longer distances,
with higher pressures, and in an
environmentally friendly way.
Fontijne Grotnes has found a solution
to bond the backing steel pipe and the
CRA pipe with the company’s full length
pipe expander, for which a patent is
pending. The company has more than
40 years’ experience in designing and
manufacturing full length pipe expanders
for the LSAW pipe industry.
The expander head, actuated by the
main cylinder and horn and drawbar
expands the pipe sections from
the inside. This ensures a constant
production process according to API 5L
through calibration of the pipe over the
full length in roundness and diameter;
straightening of the pipe; testing of
the pipe weld seam; stress relief of
material in way of the weld zone; and
improvement of mechanical properties
by exceeding the material yield strength.
For bonding CRA lined pipes by
means of a full length pipe expander,
the inner and outer pipe are telescopic
aligned and subsequently positioned on
the infeed and outfeed loading cart. The
pipe is fed incrementally with the use of
the loading cart over the expander head.
Fontijne Grotnes Group – Netherlands
Website: