Grooved advantage in the field3 November 2011
Unpredictable conditions can make the outdoor installation of pipework more difficult than on construction sites. Grooved piping systems offer advantages in laying pipework cross-country that can make them a good alternative to traditional joining techniques, writes Stephen Morrison.
Installing pipework outdoors can create numerous difficulties for engineers. Many problems may be caused by harsh external conditions, including the weather, difficult terrain, ground swell and landslides. Access to basic amenities is also often an issue. It is not always easy to bring a generator to remote areas in tough climatic conditions, whilst ensuring maximum safety levels are maintained. Delays are a common outcome.
Grooved systems help alleviate many of the problems associated with using traditional joining methods in the field. Mechanical joints are perfect for outdoor, remote use as they can be hand assembled with no need for power tools and can be mounted under any weather conditions, unlike welds which need dry pipe.
Couplings provide visual confirmation of proper installation and there is no need for X-ray testing. With a union at every joint, they offer added flexibility and are more easily adjusted if alterations are needed.
Another benefit of using grooved mechanical piping systems is that their flame-free assembly reduces the risk of fire as well as other hazards during installation. This is very important in installations outdoors in the countryside where the risk of using hotworks in dry conditions is high.
In addition a trench carrying a flanged or welded pipe must be nearly twice the width of a trench carrying a grooved line, so using grooved technology lowers labour and time requirements, as well as the environmental impact. At a recent penstock line installation for Canoe Creek Hydro in Canada, the use of the grooved system successfully narrowed the piping trench from 13m to 6m in the Pacific Rim Rainforest.
Speed and flexibility
Whether the project owner is a public agency or a private company, the speed of implementation is a very important factor. Grooved systems are dramatically faster than conventional solutions even in perfect construction conditions, lowering costs and limiting exposure.
With measurable time savings of between 35% and 50% compared to welding, grooved systems can contribute significantly to meeting tough deadlines. In harsh climatic conditions the difference is even more dramatic. Also pipe misalignments during installation are easier to resolve as angles can be changed more easily.
In addition, the use of flexible couplings in grooved systems have other major advantages. Over a number of years, land may be subject to ground movements and displacement, which can create stresses on pipes and even lead to underground breakages. This is very difficult for engineers to control, but flexible couplings offer additional security and can accommodate these potential misalignments without the need to install expensive and delicate specialised equipment.
Using flexible joints with a grooved system can also allow for contraction and expansion of pipes and associated potential movements with temperature as well as angular deflection.
Maintenance is also much easier with grooved joints, which are easily maintained and easily expandable. It can take all day to unbolt a flanged joint depending on size. Compare this with only few minutes to unlock even a large diameter grooved coupling.
The latest development in grooved technology is for medium to large diameter pipes between 350mm and 1524mm and is ideal for transporting water.
The Advanced Groove System (AGS) developed by Victaulic 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, providing increased coupling-to-pipe engagement.
A typical large-diameter joint that requires several hours to weld can be installed easily in less than an hour using Victaulic AGS couplings. With a two-piece housing and a wedge-shaped groove that delivers pressure ratings up to 2400 kPa, depending on the pipe size and wall thickness, Victaulic AGS couplings offer exceptional assembly speed and reliability.
Previous joining methods for larger-size piping systems required multiple housings to achieve the same results. Victaulic is currently the only manufacturer to offer a two-piece housing for couplings in this size range.
Summing up the benefits there is scope for significant financial savings by using mechanical grooved piping systems. Faster field installation, elimination of hotworks and reduced need for expansion joints all add up to advantages that are particularly important when choosing a system for a project in the current economic environment.
Choosing a high quality and innovative mechanical grooved piping system can bring improvements in productivity. In a sector where margins are increasingly tight, this is an increasingly attractive option for consultants, engineers and system designers alike.
Stephen Morrison is Victaulic WST global market director. For more information on the company visit www.victaulic.com.