A Sedibeng Water Board pipeline installation is set to become the benchmark for rapid and robust piping installations for municipal water supplies and similar applications in South Africa, says developer and pro- ducer of mechanical pipe joining systems Victaulic.

After the discovery of leakages in a major 500-mm-diameter welded pipeline serving the Springbok area, the Sedibeng Water Board chose consulting engineer BVi Consulting Engi-neers to design the rehabilitation and replacement work on the existing main water supply pipeline.

As a temporary replacement for part of the ageing but vital 54-km-long pipeline, a 14 km bypass surface pipeline was designed for continuous water supply over difficult terrain. It involved 300 mm carbon steel medium pipe (300 NB) on concrete plinths.

BVi, acting first as project manager and later also as consultant, relied on Victaulic grooved mech- anical pipe joining solutions to ensure continuous water supply to local areas. Employing Victaulic products allowed fast installa- tion, using local labour, and delivered considerable benefits over the flanged or welded alternative.

Traditionally, flanged or welded piping would be used on such a water distribution pipeline. However, the decision to install a grooved mechanical piping system from Victaulic was based on the speed and ease of installation and the flame-free assembly this allowed, resulting in savings on total installed cost.

Not only was the Victaulic system faster to install but its ease of assembly also allowed the use of a local workforce and created jobs in the area, says the company. Another key advantage of the mechanical pipe joining system is that it enables rapid assembly and disassembly, making tasks such as maintenance and system rerouting considerably more convenient.

Some of the major advantages of installing Victaulic products are derived from their simplicity, says the company, adding that the design of a mechanical pipe joint makes it inherently easier to work with during installation than other, more traditional, joining methods.

A mechanical joint, or coupling, comprises four basic but robust elements: the pipe groove, the gasket, the coupling housings, and the nuts and bolts. A pipe groove is formed by cold-forming or machining a groove into the end of a pipe – using an easy to use Victaulic grooving tool, it is pos- sible to do this on site, as at Sedibeng, or off site in a workshop enabling prefabrication.

The coupling gasket is pressure responsive and is encased by the coupling housing when it engages in the groove around the circumference of the pipe. The gasket then creates a seal unified joint that is enhanced when the system is pressurised.

Grooved piping systems are dramatically faster and easier to assemble than their welded or flanged equivalents. Systems in which Victaulic products are installed are also considerably faster to disassemble than other pipe joining methods, with dramatic time and labour savings, says the company.

At Sedibeng, this meant that while the process of replacing, or rehabilitating, the existing main line was in progress, the temporary bypass line could be assembled in a fraction of the time required for a welded or flanged system.

In the future, once the original line is replaced and fully func- tional, the bypass may then be dismantled in a fraction of the time required for a more traditional joining method, and parts can then be reused.

BVi-specified 300 mm Victaulic Style 77 flexible couplings and 2 333 couplings were subsequently installed on the project. Victaulic Style 77 flexible couplings feature a two-piece design that creates a flexible joint, while also reducing handling and enabling easier and quicker installation.

The coupling can withstand pressures of up to 800 psi, or 5 500 kPa, and are commonly used for a variety of industrial applications, including water and air applications.

The main reason why BVi-specified Style 77 flexible couplings were used is that, over time, the terrain may be subject to displacement and ground movements, creating potential stress on pipework and even resulting in breakages. All these stresses are difficult for engineers to manage, says the company.

Flexible couplings are especially designed to allow controlled linear and angular movement at each joint that can accommodate pipeline deflection. They offer security while also accommodating potential misalignments without the need to install the expensive and delicate specialised equipment that is necessary with flanged or welded systems.

“It did not take long to convince the Sedibeng Water Board, who soon realised the benefits of the Victaulic grooved system,” says BVi consulting engineer Winston Cloete, adding that the system clearly delivered significant advantages. “We were all confident it was the right choice.”

The ability to offer a totally secure leak-free joint, speedy installation and ease of maintenance secured the decision for all involved. “I would definitely use the Victaulic system again in a flash,” boasts Cloete.

Contractor View
Contractor NMC North was awarded the contract to install the pipework after a successful tender. They had worked closely before with both the Sedibeng Water Board and BVi.

“The biggest challenge from our perspective was the difficult terrain,” says NMC North contract manager Dallas van der Westhuyzen, adding that once the installation had started, the com- pany realised just how easy and fast the work could be completed with Victaulic couplings, despite the uneven ground.

For the local crew, learning to use the grooving tools and couplings was easy, says Victaulic, adding that simple and easy-to-understand training lasted under an hour, and from the start, teams were taking only ten minutes to complete a perfect joint. On average, the crews were completing 25 lengths of 6 m pipe each day, and by the end of the project, they were managing 37 pipe lengths each day.

The entire initial 6.5 km pipe run was completed on time, although challenges occurred with the deliv- ery of materials from other sup- pliers. In addition, the next phase of 7.5 km was completed four weeks earlier than the expected completion date.

A flanged system would have required around 16 M30 bolts and nuts to be installed and tightened at each joint, and the handling of the pipe would have been more difficult owing to the added weight.

The Victaulic grooved system offered the added advantage of reducing health and safety risks. As less time is spent on the joint, there is less exposure to worksite risks, reducing the likelihood of injuries to fingers, compared with installing a flanged system.

The crew also found it easy to check if installation was correct and the joint was securely in place simply by looking at the bolt pads and making sure they met each other without any gaps.

Meanwhile, the company says that installing a Victaulic grooved system in Sedibeng made for easier maintenance, reduced materials handling and risk of injury to workers on site, as well as reduced total installed costs.

“The grooved system saved substantially on labour and I cannot imagine reaching the same productivity level with a flanged or welded system,” says Van der Westhuyzen.

The Victaulic team also pro- vided full support with on-site training, continued site visits and technical support.

“I am convinced that this is the fastest, easiest and most trouble- free way to join pipes,” says Cloete, adding that the considerable maintenance advantages this will offer the Sedibeng authority in the future are quite clear.

“We will recommend this method for our future projects, and look forward to working with Victaulic again soon,” he concludes.