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H.E.P. - KASHMIR, INDIA |
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STEEL
TUNNEL LINING (STL) OF TWIN VERTICAL SHAFTS
WORKSCOPE
Whessoe projects are responsible for the design,
supply, fabrication, installation, and painting
of two 5.0m dia.steel tunnel linings each consisting
of a rectangular to round transition, horizontal
straight, top and bottom 90 degree bends, 200m deep
vertical shaft, bifurcation, horizontal straights,
bends and concentric reducers.
| Project
Data |
| Location |
Kashmir,
India |
| Client |
Kvaerner
Boving Ltd. |
| Owner |
National
Hydroelectric Power Corporation |
| Contract
Period |
1992
- 1996 |
| Contract
Value |
£7.0
million |
| Contract
Tonnage |
3200
te |
| Design
Code |
BS5500 |
| Material
Specification |
LT
boiler Quality Plate - BS1501-223/224-490A
LT30/50 |
| Diameter
Range |
2.75m
- 6.8m |
| Thickness
Range |
20mm
- 80mm |
| Post
Weld Heat Treatment |
Bifurcation
sickle plate assemblies |
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| DESIGN
/ DRAWINGS |
The design was completed by Whessoe
to the Clients specifications with special
consideration given to the finite element
analysis of the bifurcation and bottom
bend sections in order to minimise the
amount of Post Weld Heat Treatment required.
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| METHODOLOGY |
There were many factors to consider
when determining the execution of the
construction works including:
- Remote
location
- Treacherous
transport routes
- Avalability
of skilled labour
- Underground
Handling to limit size of
excavation
- Access
in vertical shafts
- Safety
underground
With
such restrictions it becomes necessary
to ensure the design, fabrication
and installation proceses were
fully integrated. |
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Lobsterback Installation sequence
- bottom bend
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| SITE
ESTABLISHMENT |
As it was not possible to transport
pre-fabricated sections to the
site location, a fabrication facility
was erected on site adjacent to
the installation adit on ground
built up using tunnel spoil. Foundations
were laid and a large fabrication
shop was erected.
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| FABRICATION |
The workshop was serviced by two
EOT cranes, and fitted out with
a vertical plate rolling m/c,
cutting tables, rotators, automatic
welding m/c's preheat facilities,
assembly jigs, and access platforms.
Alongside the workshop a temporary
furnace was constructed to carry
out the PWHT of the bifurcations.
Some plate preparation work required
the use of UK computer controlled
marking and cutting equipment.
This included the transition plate
sections which were fabricated
piece small and trial erected,
in the UK prior to shipping site.
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