Engineers at the Glencore-operated Boschmans colliery, in Mpumalanga, have installed 4", 6" and 8" Victaulic Style SC77 flexible couplings in both the pump systems and the large runs of pipes throughout its plant, says Boschmans engineering foreman Danie Botha.

The installation-ready couplings incorporate flexibility for expansion, contraction and deflection and feature a proprietary Grade T nitrile gasket for unmatched performance for temperatures ranging between –29 °C and 82 °C, adds Botha. He explains that the gasket is designed for optimal performance under heat and pressure, and throughout assembly and stress relaxation.

Victaulic Style SC77 couplings are rated to 4 000 kPa on all sizes of shouldered American National Standards Institute-standard thick- wall carbon steel pipes, or heavier. These couplings can join shouldered steel pipes ranging from 50 mm to 200 mm in diameter, says Botha.

Maintenance Under Way

As mining operations first began at the Twee-fontein/Boschmans colliery in the late twentieth century, the original joints on pumps and piping runs caused the pipes to leak, among other problems. As a result, some tunnels were awash with nearly six inches of water and fine slurry.

The leaks presented a maintenance challenge that prompted the site engineers to reconsider the piping technology at the Boschmans colliery. Independent tests on the Victaulic SC77 couplings showed that they achieved a substantial reduction in vibration, which would reduce the risk of leaks.

Test laboratory Nutech Testing Corporation/SE Laboratories used Victaulic mechanical couplings in its testwork and concluded that, for any pipe diameter, less vibration is transmitted with each additional flexible Victaulic coupling installed, says Botha.

Vibration Reduction

“As a critical system in the colliery, the decision was taken to first install the new couplings on the 12 Warman pumps that currently service the deep line, washing plant and sludge pumping,” says Botha.

The pipe runs are being upgraded gradually, as part of regular scheduled maintenance activities, and there is no impact on operations as all installations are being done during normal maintenance downtime.

“The difference between the Style SC77 and the older joints we used before is immeasurable,” says Botha, adding that, when old components were installed, there would be a brief “honey-moon period”, which would soon be followed by vibration and leaking.

He explains that the installation-ready design of the Victaulic shouldered couplings also proved beneficial in terms of saving time. “Each pump switch takes about 20 minutes, but only a fraction of this constitutes changing the coupling. I would say we are saving about ten minutes per installation,” says Botha.

Leakproof
Victaulic facilitated the training of the Boschmans colliery’s employees, who were shown how to assemble a joint. This comprises inserting the new installation-ready coupling onto the pipe ends and tightening the nuts using standard hand tools.

The simplicity of the Victaulic assembly with its no-loose-parts design means that the team was able to carry out the upgrades with minimal assistance and without need for a mechanical contractor.

The coupling’s centring bolt pad design offers metal-to-metal connection that gives a visual confirmation of proper installation, eliminating the need for the time-consuming X-rays and tests of welded systems.

The system was demonstrated once and the installations have since moved ahead smoothly, with an expert only a call away in case there is an issue, says Botha.

“We encountered no problems in installation and when we ran into a [problem regarding]seating alignment, it was quickly resolved with a call to the Victaulic engineer,” he adds.

The Victaulic solution has resolved the original problem of leaks, increased reliability, and reduced on-site work hours. The mine is now significantly safer and is a drier and cleaner environment to work in, notes Botha.

Noting that, in South Africa, engineers commonly refer to all mechanical couplings as ‘Victaulic’, Botha highlights that the gap between imitations and genuine Victaulic couplings is striking. “Maintenance is easier with Victaulic coup-lings and the bottom line is, where we have installed the genuine couplings, there are no longer leaks.”

Botha adds that, while quality and safety are both key considerations in the maintenance of underground pipe systems, older installa- tions are frequently replaced with like-for-like products, which means that the poten- tial benefits of new technology remain unrealised.