Giant nuts pose huge challenges for mining, energy and hazardous industrial spaces
Industries such as mining, shipbuilding, and power generation have particular requirements for extremely large nut and bolt fasteners.
These pose huge difficulties with applying specified bolt tensions because, for example, a nut weighing thirty kilograms is not going to be tightened with hand tools. These are installed or removed with sledgehammers, stud heaters, or torque wrenches, which might weigh as much as the person using them.
Installation of such large fasteners is extremely time-consuming, can be hazardous to workers, and frequently may not result in even tightening of every fastener to the precise tension required for long and safe joint life. Disassembly for maintenance can be equally slow, hazardous, and damaging to equipment and production schedules.
A proven best-practice solution is the use of the Technofast EziTite® family of hydraulic fasteners, which are proven in service to tension large bolts. Assembly and removal times are some 15-20 times faster than conventional means, while also cutting downtime and enhancing safety and joint precision.
The fasteners are so efficient and swift in operation – including operating in hazardous, hot, underground, and confined spaces – that they are used in nuclear energy plants where short exposure times to workers are of critical importance. The Technofast fasteners are commonly in use in some of the largest and most difficult critical bolting applications in machinery used in electricity generation, mining, quarrying, materials handling and high-temperature processing applications throughout Australasia, SE Asia, and the USA.
Technofast retains the NQA-1 nuclear manufacturing standard for supply to the Korean Hydro and Nuclear Power (KHNP) organisation and supplies operationally critical bolting for nuclear-fuelled electricity generating plant.
EziTite® nuts are tensioned simultaneously. An EziTite® hydraulic bolt, centre, and the operational principle, right. Technofast produces its rugged and quickly actuated precision bolt tensioning systems for demanding global uses, including mining and quarrying, generators, turbines, dragline, tunnelling, manufacturing, vibrating screens and sieves used in materials handling, piping, electricity reactor joints and covers, autoclaves for composite materials curing and foundation bolts, and construction tasks.
“EziTite technology replaces conventional mining and energy methods in situations where time is money, and safety is paramount,” says Technofast Founder and CEO, John Bucknell.
An example of their performance is their use for tensioning of boiler feed pump bolting at electricity generating plants in South Korea. The application involved 12 large M110 X 4.0 studs, which were 110mm (4.33in) in diameter with an outside diameter of 200mm (7.87in). EziTite® TR High-Temperature Hydraulic Nuts were used as an alternative to the former method of large torque wrenches weighing more than 125kg.
Four times faster installation
The Technofast EziTite method resulted in a total installation time of approximately one to two hours, using two personnel, compared with eight hours and three or four personnel using the previous method.
“Large nuts of this diameter can require terrific torque forces to achieve the desired tensioning or require multiple jack bolts on each stud to bring the job within the power range of hand tools.
“Really big nuts – such as those widely used in the mining, energy, and other industries – can easily have 24 jack bolts in total per nut, as did the nuts at the electricity generating plant in Korea.”
All of these jack bolts have to be tightened in a time-consuming correct sequence to ensure even gasket compression. This can add days of downtime to a typical maintenance operation.
“Also, when jack nut fasteners need to be removed, operations staff must untighten the jack bolts in a strict sequence to avoid failure. If they don’t, individual jack bolts can break and then the entire assembly would need to be cut off.”
In addition to vastly simplified tensioning, the EziTite nuts can overcome multiple issues experienced with heavy torque wrenches, including:
- Horizontal stud position, which makes handling difficult
- Torque-induced damage to studs, nuts, and spot face surfaces.
- Irregular torque readings that prove difficult to relate to tensions applied (a result which can be caused by common issues such as corrosion, thread damage and other factors where multiple tensioning is involved).
“Particularly in underground mines, the duty of care for safety is magnified even further – and the deeper you go, the more difficult and confined it is to get down to fix things quickly if the equipment is not reliable and productive,” says Bucknell.
Non-spark performance
Bucknell says another advantage of hydraulic nuts is that the installations are non-spark. “Coal mines, especially, don’t allow the use of methods which might generate sparks and ignite methane seeps or coal dust.”
“This non-spark requirement eliminates the use of methods such as hammering unless you have a beryllium copper sledgehammer, which still does not overcome fatigue hazards and is too slow and imprecise where a series of fasteners require even pressure across a series of nuts or bolts.”
The Technofast family of products, proven internationally over three decades, includes EziJac bolt tensioners, LiftaJac, CamNuts, EziTite clamp nuts, head nuts, bearing setters, and custom designs for specialised applications. They are distributed globally, with Technofast offices in both Australia and the US.