TPT January 2008

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Coating, Jacketing & Galvanizing Technology
83 January 2008 ›
The Metallizing Equipment Company
(MEC), India, is a thermal spray equipment
manufacturer and supplier. Arc spray
is user-friendly, and one of the more
cost efficient thermal or metal spraying
processes for applying metal coatings on
base materials. Any electrically conductive
material in wire form can be arc sprayed.
During the process, a wire
feeder pushes two electrically
charged metallising wires to
the gun. The wires meet at the
head of the gun and melt in the
electric arc, with the molten
mass then atomised and
blown onto the substrate with
compressed air. The particles
cool to ambient temperature
and coalesce into a high quality
metal coating.
A rollforming machine draws
hot or cold rolled steel through
successive stations and shapes the
material into a tube. Electric resistance
welding closes the seam left by the butted
edges.
Although no filler metal is added that
would change the chemical composition,
the welding process applies temperatures
high enough to sacrifice some corrosion
resistant properties of the base metal. The
process may also vaporise aluminium or
galvanised coating previously applied to the
rolled steel.
A contoured/scarfing tool or smoothing
mandrel removes weld spatter or excess
material from the outer diameter of the
tube surface. Many tube makers install
a two-wire electric arc spray process
directly down line from the scraping tool or
smoothing mandrel.
The spray process applies coatings of
aluminium, zinc or properties of the tubing.
Applying the spray material while the weld
seam is still hot assures a metallurgical
bond of the sprayed material with the
substrate. It improves both the deposit
efficiency and density of the sprayed
material and allows the coating to blend.
M/s Metallizing Equipment – India
Fax: +91 291 2746359
Email:
Website:
Launch of new all-terrain
pipe coating
Saint-Gobain Pipelines, UK, is a supplier
of ductile iron pipes, fittings, valves,
access covers and gratings, and also
produces cast iron drainage systems for
above and below ground. The company
has introduced a new coating solution that
offers total protection, no matter what the
soil conditions.
The TT (Total Terrain) external coating
system comprises thick, organic coatings
which provide a complete barrier between
the pipe and the surrounding soil. The
system extends the capability of Saint-
Gobain’s water and sewer pipes to all soil
conditions.
The company’s product manager,
Mr Nigel Ward, explained, “ PAM Natural
and PAM Integral Plus with their 85 per
cent zinc and 15 per cent aluminium
alloy coating are suitable for use in 85
per cent of all soil conditions. However,
in extreme situations, tape wrapping
has traditionally been used for a higher
degree of protection. The TT coating
is an external protection system that
provides a total barrier coating, which
offers cost savings through quicker and
easier jointing techniques onsite.”
The TT coating system consists of an
efficient PEC (polyethylene) or PUX
(polyurethane) coating. DN80-700 pipes
are supplied with the PEC coating, which is
a 2mm thick extruded polyethylene coating
applied over 200g/m² zinc using a heat
bonding adhesive co-extrusion technique
which is electronically tested to ensure it is
holiday free.
When assembled, the joint area is protected
by either an easily fitted rubber sleeve
or heat-shrink wrap. DN800-2000 pipes
are supplied with the PUX coating, 900
microns thick with the joint area protected
by a holiday free epoxy paint requiring no
further protection.
Conforming to BS EN 545 and BS EN
598, the robustness of the coating system
ensures the minimum risk of damage
during transportation and installation.
Saint-Gobain Pipelines – UK
Fax: +44 115 932 9513
Email :
Website:
Automatic zinc coating plant for tube seam
fi The arc spray process
› MEC manufactures and supplies thermal spray equipment