Mechanical joints are increasingly being used in the transport of water, owing to the advantages offered by grooved piping systems in laying pipework cross-country, which make them superior to traditional joining techniques, mechanical pipe-joining systems manu-facturer Victaulic regional manager Barry van Jaarsveld tells Engineering News.

“Victaulic’s latest development in grooved technology is for medium- to large-diameter pipes between 350 mm and 1 524 mm and is ideal for transporting water,” he says.

Van Jaarsveld says the Advanced Groove System (AGS), which Victaulic is continuously upgrading, is designed to offer enhanced strength and reliability through a more robust coupling housing and a patented wedge-shaped roll groove that is deeper and wider than those of other couplings in the market, providing increased coupling-to-pipe engagement.

Victaulic, in January, expanded its AGS range in South Africa with the introduction of the AGS Vic-Ring system, which consists of Style W07 rigid AGS couplings, the Style W77 flexible AGS couplings and specially designed rings containing a patented AGS profile.

“The rings are butt-welded to the pipe ends, and the coupling is assembled on two rings — one on each pipe end — to complete the joint. “Style W07 couplings create a completely rigid joint, while Style W77 couplings allow limited linear and angular pipe movement at the pipe joint. These couplings can be used to accommodate thermal expansion and contraction, vibration, seismic movement and applications requiring flexibility,” explains Van Jaarsveld.

In addition, Van Jaarsveld states the Victaulic Style 77 flexible coupling underwent a significant upgrade in the past year, and its new two-piece design reduces excess handling concerns and enables simplified installation.

Style 77 is rated for 300-pounds-a-square-inch (psi) service from 350 mm to 550 mm, and for 250 psi service in the 600 mm pipe size. The two-piece Style 77 coupling was previously only available for pipes sized 20 mm to 300 mm. A multipiece housing was required for pipes with larger diameters. Style 77 is available with a grade E ethylene propylene diene monomer rubber gasket for water services, or a grade T nitrile gasket for the handling of air with oil vapours.

Van Jaarsveld notes that installing pipework outdoors can create numerous difficulties for engineers.
“Many problems may be caused by harsh external conditions, resulting from bad weather, difficult terrain, ground swells and landslides. Access to basic amenities, such as electricity, is also often a challenge. It is not always easy to bring a generator to remote areas in tough climates while ensuring maximum safety levels are maintained. Therefore, delays are a common outcome,” he says.

However, Victaulic says its grooved systems help alleviate many of the problems associated with using traditional joining methods in the field.
Van Jaarsveld points out that mechanical joints are perfect for outdoor and remote use as they can be assembled by hand without power tools and can be mounted under any weather conditions, unlike welding which requires dry conditions.

“Couplings provide visual confirmation of proper installation and there is no need for X-ray testing. “With a union at every joint, the couplings offer added flexibility and are more easily adjusted if alterations are needed,” he says, adding that another benefit of using grooved mechanical piping systems is flame-free assembly. This reduces the risk of fire, as well as other work-related hazards during installation, which is important for installations in dry conditions, where the risk of using hot-works outdoors in the countryside could lead to veld fires.

Further, Van Jaarsveld notes that a typical large-diameter joint that requires several hours to weld can be installed easily in less than one hour using Victaulic AGS couplings.

“With a two-piece housing and a wedge-shaped groove that delivers pressure ratings up to 348 psi, depending on the pipe size and wall thickness, Victaulic AGS couplings offer assembly speed and reliability,” he asserts.

Previous joining methods for larger-sized piping systems required multiple housings to achieve the same results.

“Victaulic is the only manufacturer in the world to offer a two-piece housing for couplings in this size range,” boasts Van Jaarsveld.

He explains that in 2011 leaks were discovered in a major 500-mm-diameter welded pipeline serving the Springbok area, in Gauteng. The Sedibeng Water Board contracted consulting and design engineer BVi Consulting Engineers to design the rehabilitation and replacement work on the existing main water supply pipeline. As a temporary replacement for part of the aging but vital 54-km-long pipeline, BVi designed a 14 km bypass surface pipeline that accommodated continuous water supply over difficult terrain. It comprised 300 mm carbon steel medium pipe on concrete plinths.

“BVi, initially acting as project manager and later as a consultant, relied on Victaulic grooved mechanical pipe-joining solutions to ensure continuous water supply to local areas. “The Style 77 couplings allowed fast installation using local labour and delivered considerable benefits over the flanged or welded alternative,” says Van Jaarsveld.

Green Aspects

“Even before the evolution of green building, the grooved piping system has been providing a more efficient, cleaner and safer system, compared with other pipe-joining methods, such as welding, soldering or brazing,” he states, adding that by reducing the need for these techniques, air quality is improved, less particulate matter is released into the atmosphere and fire risk is decreased.

Further Van Jaarsveld says pipes that are joined by welding or soldering require vast amounts of electricity for prolonged periods, consuming up to 4 000 W/h of energy on a 200-mm-diameter nominal joint.

“A Victaulic grooved mechanical pipe joint does not require the use of electricity during installation, reducing the draw on burdened power resources,” he explains.

During installation, Victaulic mechanical grooved piping systems significantly reduce or eliminate waste and emissions, such as lead oxide, carbon monoxide, volatile organic compounds and hydrochloric acid, in addition to many other harmful particles and gases, and noise pollution on the jobsite, providing a safer and healthier environment.

Victaulic is a member of the Green Building Council of South Africa and is involved in the world’s foremost environmental assessment method and rating system for buildings, the Building Research Establishment Environ-mental Assessment Method.