PROJECT HISTORIES - FRP/GRP PIPES
• Otahuhu Power Station Otahuhu, Auckland, New Zealand.
• Santa Rita Power Plant, Batangas Bay, The Philippines.
• Pelican Point Power Station Adelaide, South Australia.
• Christchurch City Council, Bromley, New Zealand.
• Downer Engineering, Genesis Energy, Huntly, New Zealand.
• MacKay City Council, MacKay, Queensland, Australia.
• Brian Perry, Hutt Valley Water, Upper Hutt, New Zealand.
|COOLING TOWER PIPEWORK
Otahuhu Power Station Otahuhu, Auckland. New Zealand.
Fibreglass and PVC cooling water pipes were supplied to the gas fire Otahuhu Power Station, built by Mitsubishi for Contact Energy.
The majority of the piping was installed in the cooling tower, which was of an induced draught timber construction. There are eight individual bays making up the cooling tower and within the labyrinth of each bay tower the fibreglass piping is circulating the cooling water.
Each bay has it’s own unique piping system consisting of 700
dia. riser pipe and from that the supply lines fed the heat exchangers and spray
nozzles. Approximately 1 km of piping was supplied to Otahuhu Power Station
plus 400m of 400 dia. pipe – supplying the saltwater from the intake at the pump
house to the towers.
Two GRP chemical tanks, 20,000 litres and 5,000 litres, were also supplied to the site for another subcontractor. These tanks are for the chemical dosing of the circulating water.
|COOLING TOWER PIPEWORK
Santa Rita Power Plant, Batangas Bay, The Philippines.
Fossil fuel power plants require vast quantities of cooling water to get maximum efficiency from their steam
turbines. For this reason large power plants are usually located close to the large rivers or the sea. In the case of
Santa Rita, the plant is located on the shores of Batangas Bay enabling the use of seawater for cooling and
delivery of the power plant heating fuel by marine tanker.
The power plant size of 1000MW required twin inlet and outlet pipes of 2.5m dia. with GRP being chosen in
preference to traditional materials such as concrete or steel which were allowed in the tender documents.
GRP pipe is rapidly becoming the industry standard for power plant cooling water applications for the obvious
reasons that dictated it’s choice for Santa Rita:
||The first and most obvious was the total corrosive resistance of GRP pipe particularly for handling seawater.
||Its light weight was a decided advantage at Santa Rita where the pipe runs to the sea were through swampy
lagoons and weak sub-soils. Heavier steel or concrete would have required extra provision to support the
added weight. In most cases with GRP, the net operating weight is less than the original ground weights.
||Santa Rita is located in a high activity seismic zone and directly over fault lines. It was proven that GRP pipe
being inherently flexible and strong in tension required no further provision for earthquake serviceability.
||The availability in lightweight lengths up to 12m enables quick installation allowing the use of lightweight
plant. An aspect that became very important in the flooded Santa Rita site.
||Finally the cost of GRP was competitive.
A prime requirement before work could start was Maskell’s ISO9001 registration and a full evaluation by the Clients consultants and Seimen’s Power Generation, the Project Managers, of the manufacturing facilities and detailed design analysis.
Maskell’s order for the pipe came late in the main contract and because it was so late
there was not time to establish on site so the pipes were manufactured and shipped
from the Auckland plant. This required the chartering of two exclusive vessels to go
“door to door”, with the first ship arriving to pick up it’s cargo four weeks after the date
of order and the final ship six weeks after that.
This gave Maskell’s two and a half months to complete the contract from a standing start. Two weeks to submit full Quality Assurance/Method Statements and detailed design to AWWA C950 standards based on site geotechnical information. The remaining time after approval to manufacture, ready to uplift 2200 meters of 2.5m dia. pipe, complete with two 2.5m dia. 90º mitred duckfoot bends and numerous special fittings! The challenge was met.
New ground was broken in the analysis for seismic activity that is of interest to GRP pipe suppliers and users. The
initial approach by the specifiers was to treat GRP the same as rigid pipe (concrete) and they originally specified a
flexible coupling every 10m of pipe to turn a ‘rigid’ pipe into a flexible one. Maskells pointed out, as so many GRP
pipe manufactures have done before, that GRP pipe is in itself flexible and multiple use of couplings was not
necessary. This was not accepted until an incorrect seismic analysis using the above ground code, appeared to
show that the pipes would separate at the couplings.
Maskell were asked to comment and with the help of one of the worlds leading seismological engineers, were able
to demonstrate that not only was the initial evaluation inappropriate but also develop a completely new analytical
tool for subterranean seismic design. Correct analysis demonstrated that the pipe was sufficiently flexible and
strong to handle the most rigorous Zone 4 seismic loading whether butt strap jointed or installed with couplings.
As so often happens the installation bought it’s own problems. An ingenious approach by the contractor was
to incorporate the pipeline in the bed of the causeway to the wharf. This reduced the excavation considerably
giving a much more efficient installation. It did however require stone support columns in some areas and this
in turn opened up an unexpected aquifer that prevented full dewatering of the pipe trenches. Installation
therefore had to take place in a semi-flooded trench which increased the difficulty considerably.
Maskell engineers worked with the contractor on site throughout the contract to help solve these and any
other issues that arose to ensure a successful and economic installation.
At the time of writing a stage II expansion was about to take place adding a further 500MW of power.
This time a further 1000m of GRP pipe was specified.
|COOLING WATER PIPE LINES
Pelican Point Power Station Adelaide, South Australia.
Fossil fuel power plants require vast quantities of cooling water to get maximum efficiency from their steam turbines. For this reason large power
plants are usually located close to the large rivers or the sea. In the case of Pelican Point Power Station the plant is located on the Outer Harbour
close to the Port of Adelaide. Cooling water from the sea inlet is circulated though the heat exchanges and returned back to the sea.
The power plant size of 500MW required twin inlet pipes of 2.2m diam. and an outlet pipe of 2.8m diam. Alternative materials and international and
local suppliers were evaluated before the contract was given to Maskell’s in early October for full delivery by the end of the year.
Maskell design engineers worked closely with the contractor and his consulting engineers to establish the most economical installation and
backfill materials required for the satisfactory performance of the pipe. This required full evaluation of bore samples taken at the site and geotechnical reports and advising on the optimum trench widths and depths
Maskell engineers associated on the selection and evaluation of properties of bedding and backfill materials attending site on a number of
occasions.This enabled economic use of excavated native material for backfill both onshore and offshore.
The pipe was manufactured in our Melbourne factory and delivered to site by road. A trench was excavated and dewatered between sheet piling
to take the inlet and outlet pipes.
Crushed rock bedding was prepared and the pipe placed in and joined by butt strap welding. Flexible couplings and rocker pipes were used
at all connections to fixed structures. Temporary bulkheads were installed in the pipes to enable controlled filling when the time came to flood
The 2.8m diam. outlet pipe ran about 150m into the sea to distribute the warm water though a 50m by 2.2m diam. diffuser with multiple jet outlets.
Both the outlet pipe and the diffuser were fully preassembled on land and floated out into position with carefully controlled buoyancy before being
sunk into position in a prepared trench. The outlet system was then backfilled completing this portion of the contract in good time.
The under water section of the outlet pipe was then connected to the shore section by a coupling ready for flooding and removal of the isolation
bulkhead when the time was right.
|PRESSURE SEWER PIPING
Christchurch City Council, Bromley, New Zealand.
Fibreglass pipes and fittings were supplied to the Pump Station 11 upgrade. This is the final pump station before
the sewer lines go into the Bromley Waste water treatment plant and the existing pump station had to remain
operational during the building of the new pump station.
GRP pipe was used because of the long lifespan and the
ease of site running large diameter pipe from pump station to the valve chamber and then connection with existing
DN1200 pipe cast into concrete walls
with puddle flanges and mitred joints
used to lay pipe to valve chamber.
DN1200 pipe from valve chamber to
existing pipe with GRP pipe spigot
directly into rubber ring jointed
|COOLING WATER PIPING
Downer Engineering, Genesis Energy, Huntly, New Zealand.
Fibreglass and PVC cooling water pipes were supplied to the gas fired Huntly Power Station, for two projects, the
addition of a cooling tower to the existing plant and the construction of a new power station.
The cooling tower pipe work ranged in size from DN1800 down to DN400 and included swept bends, flanges and
both buried and above ground pipe. DN1200 pipe connected the cooling tower to the pumps. Full face fibreglass flanged connections were used for non-return
valves and valves.
Cooling water pipe work ranges from
DN50 up to DN500 with pressure rating of 10Bar for the plant room of the new gas fired Huntly Power Station.
Maskell Productions supplied pipe to site in transportable spools and supplied site staff to join the spools on site and make any adjustments. Flanges for this contract were provided with galvanised steel backing rings.
|SCOPE OF HUNTLY PROJECT
|Pipe DN900 to DN1800:
|Flanges DN900 to DN1800:
|Pipe DN50 to DN500:
|Flanges DN50 to DN500:
|Joints DN50 to DN500:
|WASTE WATER RISING MAIN
MacKay City Council, MacKay, Queensland, Australia.
This project was designed to recycle most of Mackay's wastewater to better protect the Great Barrier Reef from
250 tonnes of nutrients entering the system every year, and protect and rehabilitate over committed ground water
resources which are at risk of seawater intrusion.
The Bakers Creek waste water treatment plant was built to treat and recycle waste water to allow use for irrigation.
A 6.1km DN650 pipeline to transport recycled water from the plant to a reservoir was installed using GRP
(fibreglass) pipe. The pipeline was supplied in 11.5m lengths with dual rubber ring joints to allow swift installation.
In addition the rubber ring joints could be fully pressure tested for seal integrity as they were laid.
The challenge was to supply 6.1km of DN650 pipe to site at MacKay. Pipe was delivered in several
shipments to allow a start on the straight lengths of the pipe run with several areas
started at the same time. This was done to avoid laying pipe during the approaching
wet season, up to 250m a day was installed.
To allow maximum flexibility with the installation Maskell Productions supplied staff to site
to laminate joint (butt and strap) minor direction changes in the pipe line. Where greater
changes in direction were required swept bends were welded into the line with axially
restrained pipe one either end of the bends extending out until soil friction allowed rubber
|PRESSURE SEWER PIPING
Brian Perry, Hutt Valley Water, Upper Hutt, New Zealand.
Fibreglass pipes and fittings were supplied to the Silverstream emergency overflow facility.The pipe work was used to connect the outlet of the pumps to the overflow tank, bell mouth opening were cast into
the concrete wall of the tank.
DN500 GRP pipes were connected via full face
GRP flanges to pump outlets with a 10m rise to
DN760 GRP pipe was used to deliver to the
tanks and the pipes were installed in cradles attached to
the tank walls.