nroom yields results
expertise in working with
titanium from past projects.
In 2015, LEWA used titanium
materials to build pumps and
piping systems for the largest
chemical injection module in
the company’s history used on
a Floating Production, Storage
and Offloading (FPSO) vessel.
“For the sulphur recovery
plant project, we built on this
expertise and added in-house
titanium piping manufacturing
to the portfolio of LEWA’s own
capabilities,” explains Nathan.
The customer wanted a
system that was suited for
the sodium hypochlorite
application, and as a result,
very high requirements were
placed on manufacturing the
components. “All the titanium
welding processes had to
be carried out in a separate
welding room with its own
special climate control,” says
Nishar Parakkunnath, Head of
production at LEWA Nikkiso
Middle East. “The surfaces
being welded were supposed
to have a temperature of at
least 15 °C and no more than
90°C. After the welding,
all welding joints had to be
checked by a visual inspection
before any cleaning.” The
inspection focused specifically
on the heat-affected zones
(HAZs) and on the potential
surface contamination of
the welding joint. “Based on
prior experiences with other
manufacturers, the customer
had laid out very stringent
acceptance criteria with respect
to the discoloration of the
joint during welding,” explains
Venkatesh Chidambaram, QC
Manager at LEWA Nikkiso
Middle East. “For this reason,
the joints had to be pure silver
in colour before brushing.”
To meet the required
criteria, LEWA Nikkiso Middle
East built its own 45 m² clean
room at its factory in the UAE.
Furthermore, the company
purchased special welding
equipment and accessories for
the titanium welding process.
“After that, we adapted the
direct and indirect welding
parameters for the gas tungsten
arc welding method that was
used,” says Parakkunnath.
“These parameters included
“After all inspections were conducted, the total rejection rate
amounted to a mere 1.18%”
energy input, travel speed, gas
flow rate for inert, return and
follower gas, as well as the
preheating and intermediate
flow temperature.”
The welders paid special
attention to the gas shield
around the connection. Without
specific precautions, titanium
material becomes contaminated
right away from the atmosphere.
“This type of contamination
potentially reduces the service
life of the welding and base
material. Our customer wanted
to eliminate any chance of
this happening by imposing
stringent specifications,”
explains Chidambaram. This
is why it was critical to protect
the welding pool adequately by
consistently maintaining the gas
shielding to cool down metal
surfaces and prevent oxygen
ingress.
HIGH-QUALITY WELDING
RESULTS
The results of these welding
tests were monitored in each
case by the welding supervisor
and quality inspectors. Based
on these results, LEWA
Nikisso Middle East worked
out improvement criteria to
attain the required welding
joint quality. This is how
the company subsequently
reached such an outstandingly
high proportion of flawless
welding joints: 335 out of
339 in the project. “After all
inspections were conducted,
the total rejection rate
amounted to a mere 1.18%,”
says Chidambaram. “This
result has been recognized and
validated by our customers.”
The titanium welding work
was completed in a time frame
of 30 days and the complete
chemical injection package
was delivered early 2019.
The package will be in full
operation in 2020.
LEWA GmbH
www.lewa.de
0049 7152 14-0
www.fastening-solutions.co.uk 29
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