TPT November 2012

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Blasting and coating
November 2012 99
Duratrim solves welding problems
A COMMON problem in the HF welding
process for coated materials is the
inclusion of oxides in the weld zone: this
can cause premature weld failure and
quality control rejects. This can lead to
huge costs in scrap and ultimately loss
of reputation with the end customer.
Duratrim is a new edge conditioning
system specifically designed to solve the
problem with aluminised and galvanised
tubular products.
It works by removing a very small
amount of material from the top, bottom
and sides of the strip prior to entry into
the forming mill. The unique design
differs from other edge preparation
systems as Duratrim allows the strip
to ‘float’ through the unit rather than
‘forcing’ it through scarfing inserts (like
other systems). This is made possible
by four pairs of carbide scarfing inserts
mounted in specially designed tool
holders. The tool holders operate with
continuous positive pressure on the strip
moving in both vertical and horizontal
directions, thus ensuring small variations
in strip profile, width and thickness are
taken care of automatically.
The system requires only compressed
air to operate and has individual pressure
adjustment of all eight scarfing inserts
making it possible to individually adjust
the amount of material removed. Insert
and tool holder design give an edge
profile at the welding point which can
reduce the inside and outside welding
bead. Less ‘squeeze’ out is required
leading to significant benefits including:
reduction of strip width offering material
savings; increased production ‘uptime’;
higher weld integrity; increased life from
ID/OD scarfing tools; and increased life
from impedors.
The unit is positioned at the entry end
of the mill between the accumulator
exit and mill forming bed. The strip is
then simply fed through the Duratrim
and the insert tool holders adjusted
prior to starting. After starting no further
adjustment is normally required and
standard cross welds will comfortably
pass through without disruption to
production. Duratrim can also be used
offline for edge treatment in a ‘coil to
coil’ process; typically this would be for
TIG mills where one unit is utilised for
multiple process lines.
While Duratrim is particularly effective
for aluminised and galvanised strip it
can also be used for regular steel as
well as non-ferrous materials such as
stainless, brass and aluminium.
Superior Technologies Europe – UK
Website:
Reducing problems with welding