The effectiveness of nondestructive testing (NDT) is enhanced by rope access, as it ensures the rapid deployment of skilled technicians to carry out this critical inspection work, posits industrial rope access specialist Skyriders.
NDT is an ideal form of preventive maintenance, and is used extensively by State-owned power utility Eskom during shutdowns.
Rope access is the most cost effective and efficient means of gaining access to difficult-to-reach areas such as boilers during shutdowns, Skyriders marketing manager Mike Zinn explains. These are categorised as either intermediate shutdowns (of nine to ten days’ duration for inspections) or general outages (which can take up to 16 days for the inspections).
In general, power station shutdowns have a limited duration, during which time critical components are inspected, in addition to any trouble spots identified from previous inspections. Following this, the necessary repairs or maintenance is carried out.
“The first step is understanding the client’s specific requirements. In terms of power stations, Eskom already has a Wear Failure System in place for inspection purposes. This guides us in our particular scope of work, which can range from visual inspection only to ultrasonic wall-thickness measurement (UT), dye penetrant or magnetic particle testing, and NDT. All these inspection methods are aimed at determining any defects with the various components,” Zinn points out.
Skyriders is able to carry out the full suite of inspection services using rope access. Its in-house expertise runs the gamut from NDT to concrete repair, confined spaces, painting, bolting, rigging and welding, and work-at-height. “Our main differentiator is that we use rope access, whereas other companies use the more traditional means of access.”
Most of Skyriders’ scope of work for Eskom is based on UT wall-thickness measurement and visual inspection, with dye penetrant and magnetic particle testing both a close second. These hi-tech methods are favoured as the human eye cannot detect all possible cracks.
“If a power station boiler has a rupture of a tube due to wear, it can result in extensive damage, which necessitate a shutdown for inspection and repair. This can translate into load losses for the national grid.” Thus, the major advantage offered by rope access is the cost- and time-saving, which is critical to limit the duration that a power station is out of commission.
“Erecting and dismantling the more traditional access means can take up a sizable portion of the shutdown programme. With rope access, the minute the permit is cleared and it is safe to enter, our technicians carry out the necessary rigging in order to gain immediate access. This means that we can have skilled personnel anywhere in a boiler within an hour, or within two hours at most for hard-to-reach places,” Zinn elaborates.
All Skyriders’ technicians have either Level 1, 2 or 3 accreditation from trade organisation the Institute of Working at Height, the governing body that regulates the work at height industry in South Africa. Level 3 is the most advanced, requiring about 2 000 hours of experience, in addition to rigorous training and evaluation. Level 1 and 2 technicians cannot work unsupervised and must be accompanied by a Level 3 technician.
“While rope access appears extremely adventurous to the untrained eye, there are strict standards and regulations, including ISO, which means that fatalities are virtually zero,” Zinn stresses.
He emphasises that rope-access technicians have to be switched on and highly motivated.
Progress at Eskom
Skyriders is powering up inspection and maintenance on a project at Eskom, the company noted in a March announcement.
Skyriders has had a permanent rope access maintenance and inspection team at a large Eskom power station near Ogies in Mpumalanga for 12 years.
The rope-access specialist has assisted the electricity utility with various tasks, such as internal boiler inspections, PF pipe inspections, coal bunkers, terrace bins, precipitator hoppers and ducting, Zinn explains. It has also carried out maintenance work on the roof and side sheeting, bucket elevators and smoke stacks.
In addition to a permanent crew, Skyriders also has a large multiskilled team available to carry out other essential maintenance and inspection tasks during any planned or unforeseen outages at Eskom’s fleet. “What gives us our competitive edge is our extreme flexibility and responsiveness in this regard,” Zinn comments.
This has resulted in Skyriders enjoying a close relationship with Eskom for over 15 years, carrying out work at most of Eskom’s 13 power stations. While the more traditional means of access have been used in this sector, Zinn argues that rope access is the ideal solution, as it provides efficient and quick access to high-elevation structures. It also enhances overall site safety during shutdown periods.
“The rapid rigging and de-rigging of self-sufficient teams allows trained technicians the flexibility to complete tasks much quicker. Time is of the essence during any kind of shutdown situation at a power station, as it impacts on the national electricity grid,” Zinn emphasises. “Our technicians are responsible for the full remit. Rope access also allows a single team to undertake numerous tasks at various locations.”
Skyriders’ recent scope of work at various Eskom power stations has involved the application of protective coatings to two 250 m smoke stacks, steel-erection rigging and bolting, concrete repair and grouting on water-treatment plants.
Apart from the boilers themselves, power stations have additional structures that require regular inspection and maintenance. These include smoke stacks, cooling towers, turbine halls, ash-handling plants, coal storage facilities and piping.
Skyriders offers a variety of rope-access- aided services to numerous industries, such as power generation, petrochemicals, mining, heavy industry and facilities management. These services include NDT and inspection, concrete inspection, maintenance and repairs, application of coating systems, work at height safety systems, welding, and confined space rescue and standby, among others.