Page 17 - GlobalEyes Edition 9 - November 2012

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Step 4
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The open root TIG welding of each joint was extremely difficult and introduced
many challenges due to the restricted physical access to the root itself. After
overcoming the root and hot pass issues we then entered an even more
difficult phase of the fabrication which included full penetration weld fill out
with Flux Cored Wire - FCAW. This was performed in the horizontal position
but posed new challenges with positioning and torch angle and access.
As the finished product departed for the east coast we were able to look back and reflect on lessons learned and the
knowledge we gained in the manufacture of this complex component. We now have a much better insight into the
magnitude and complexity of this type of project and we look forward to applying this knowledge to our next opportunity.
Following re-inspection of the welds after heat treatment the assembly was
prepared for the hydro testing stage. Special cover hardware was bolted
to the operating ends of the valves and cover plates were welded over the
suction and discharge openings sealing the unit for the hydro test at 1570
The assembly came through with flying colours and the hydro test hardware
was disassembled prior to cleaning and coating.
Because this assembly was being shipped on a flatbed truck, we had to build
a special support to ensure its safety while in transit and shrink wrap the
entire unit to protect it from the elements during its long journey.
The final destination for these units will be the Hudson Power Plant in New
Jersey which provides electricity for a large part of that region. The timing
of the plant shutdown for installation provided an extremely tight window
for delivery; the consequences of missing the window would have been
devastating. Due to the efforts of all Bradken operational, engineering and
management employees at the Tacoma facility going above and beyond to
overcome technically challenging obstacles, delivery was achieved within the
required timeframe.
All full penetration welds were then inspected with Magnetic Particle
Examination - MPE and then radiographed. The assembly was then ready for
post weld heat treatment which was accomplished using a localised stress
relief utilizing resistance heating coils and insulation.
The valve assembly is readied for Post Weld Heat Treatment using resistance heating coils, insulated with thermal blankets.
TIG welding of a joint
Welding of the Hydro Test seal covers
Red protective paint was applied to prevent rust prior to installation
Polyurethane shrink wrap was used to protect the assembly during transport.
Finished product departs for its final destination