TPT November 2010

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104 November 2010 ›
Blasting, Coating & Galvanizing
METALLISATION provides metal spraying
and anti-corrosion protection systems
around the globe, and boasts a number
of successes within the tube and pipe
industries.
Metallisation equipment and processes
are thought particularly effective in
re-coating weld areas of pre-coated
tubes produced by a tube-forming mill.
Tubes can be produced using pre-coated
steel strip, which is available with zinc
coating (galvanised), aluminium coating
(aluminised) or Zn/Al Alloy coating,
available under various trade names. The
tube is formed by electrical resistance
welding (ERW) of the longitudinal
seam. During the welding process the
heat generated, coupled with the tooling
operation to remove the weld fins, destroys
the tube coating around the weld area,
which, unless re-protected, will corrode.
The re-protection of weld damage is
achievedbyapplyingametal sprayeddeposit
that matches the tube coating. Metallisation
can metal spray the weld damaged area
with pure zinc, pure aluminium or a zinc/
aluminium alloy. This is believed to be the
only method of in-line repair that offers
the flexibility of producing tube with zinc,
aluminium or Zn/Al coatings.
The Metallisation Arcspray 528E-ICC
is a heavy duty high performance pistol,
specially designed to work reliably in severe
and extended operating conditions.
To apply the metal spray to the ERW
seam, the Metallisation weld repair system
is installed on to the tube mill. The spray
pistol must be located as close as possible
to the fin removal tool and, ideally, within
one metre of the welding coil. When
spraying a zinc coating the pistol needs
to be around 30mm from the arc point.
The spray current, which relates to the
spray rate of the pistol, can be varied in
accordance with the line speed to ensure
an even coating on the seam, even when
the line speed changes, eg during ramp-up
and ramp-down. Typical line speeds of 60
to 110 metres per minute are normal when
arc spraying, but speeds outside of this
can be catered for. It should be noted that
the coating quality may be affected by the
mill line speed and size of the tube and
slight adjustments may be required.
The main benefit of the Metallisation
Arcspray 528E-ICC system is its reliability
in automated applications. In the Arcspray
process, the raw material – a pair of metal
wires – is melted by an electric arc. The
molten material is atomised by a cone of
compressed air and propelled onto the
ERW seam. This spray solidifies when it
hits the surface of the tube to form a dense
coating, which re-coats the tube weld area
to protect against corrosion.
Major advantages of the Arcspray
process are that the coatings are available
for almost immediate use, with no drying or
curing times; there is no risk of damaging/
distorting the component and the use of
only compressed air and electricity mean
more economic coatings.
Metallisation – UK
Fax: +44 1384 237196
Email:
Website:
Stopping seam corrosion
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Forming machines of butt-weld pipe fitting.
Beveling machines for pipe fittings.
Pipe end beveling machine for
Prefabricated pipe plant.
Pipe fittings for fire protection,
petro-chemical &pulp industry, etc.
Auto threading m/c for socket &nipple.
Transfer machine & special purpose m/e.
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