Precision and hydraulic special service equipment manufacturer Power Team says its SPX bolting system, which it supplies to contracting companies in the South African wind energy sector, enables these companies to significantly increase windmill erection speed, reduce construction costs and ensure accurate torque and tension levels on every bolt.
“The SPX bolting system for windmills was introduced prior to the accelerated programme to erect wind farms in the country; however, we have made large investments and continue to develop the system to ensure that SPX bolting products remain at the edge of bolting technology,” says Power Team South Africa GM Ian Bennett.
“The system ensures accurate torque and tension levels on every bolt, enabling engineering, procurement and construction management (EPCM) companies to efficiently complete construction,” he adds.
He notes that EPCM companies are under significant pressure to find the best installation techniques and equipment available to reduce costs and enhance safety.
“Because of the [limited] timeframes allocated for windmill installations, speed is the main benefit of the SPX bolting system,” says Bennett, adding that the system includes a hydraulic torque wrench high cycle (TWHC), the PE 45 continuous pressure pump, a compact pump, an electric pump and wind tensioners.
Unlike standard two-stage hydraulic bolting systems that drop to a low pressure for second- and third-stage torqueing, the SPX bolting system introduces infinite-stage pump technology, which results in the pressure dropping in carefully controlled intervals, says Bennett.
“This means that, when it is time for the second and third rounds of progressive torqueing, wrenches have exactly the correct pressure, which enables significantly faster bolting – up to 200% faster. This technology is unique to the SPX bolting system.”
Bennett says the SPX bolting system’s TWHC has a longer service life – up to three times that of standard torque wrenches. “Better designs and workmanship have given the SPX torque wrench a life of about 30 000 cycles at full torque. So, for windmill applications at an average of 60% of the maximum torque capacity, the SPX can perform for up to 50 000 cycles.”
The cost of the system varies according to the equipment that is required, “which can range from R45 000 for a single wrench to more than R500 000 for a complete system, including the hydraulic torque system and the hydraulic tensioning system”, he says.
He adds that, for the first time, EPCM companies can install multiple wind farms using the same tool set, owing to the SPX bolting system. “At a price premium of about 15%, in addition to a standard wrench, which is still significantly competitive, compared with other products, companies can further achieve significant cost savings using the SPX bolting system’s products through economies of scale, which similarly applies to turbine maintenance and the retorque of bolts.”
The wrench features a 35º stroke, which is a larger segmental stroke than that of most available wrenches, and comes standard with a multiswivel connection to prevent tool and hose damage, says Bennett.
In combination, the wrench and pump system, “referred to as a power pack”, reduces erection time by days on an average-sized windfarm, which means EPCM companies can realise substantial savings in terms of crane hire and access hire, as well as labour costs, he says.
The SPX bolting system’s range includes a compact pump, which is ideal for wind tower maintenance and checking bolt torque integrity. “It weighs less than 18 kg and has a cooling fan and is suitable for continuous operation in ambient temperatures of between –25 ºC and 50 ºC,” explains Bennett.
He adds that wind tower tensioners, with fully enclosed load cells, antislip grip and piston stroke indicators, further reduce operator fatigue and increase safety when tightening bolts in and around reduced clearance areas.
Bennett says the SPX bolting system has been used on the Hopefield wind farm, situated 100 km north of Cape Town. Construction on the wind farm started in 2012, with the farm having started commercial operation at the beginning of this year.
Meanwhile, Bennett says it is important for EPCMs, windmill manufacturers, construction teams and bolting contractors to be satisfied with the quality of bolting equipment only when they have the right torque levels that can be applied consistently throughout a windmill.
“That is why Power Team has spent R250 000 on a test bench for the SPX bolting system. The test bench is connected to a computer that prints out certificates based on successful test completion, ensuring that only work of a high quality is produced.”