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8 Volstruis StreetRant-en-DalKrugersdorpGautengTel:+2782 963 3667www. victaulic.com

AN INTRODUCTION TO GROOVED MECHANICAL PIPE JOININGGrooved mechanical pipe joining systems provide an attractive alternative to welding and flanging for engineers, installers and owners alike. They allow quick, easy, safe installation and maintenance to meet compressed project schedules, along with maximum operating efficiency and built-in sustainability. Above all, the benefits combine to give a lower total installed cost over the life of the system.

Using grooved systems dramatically reduces the amount of installation time and saves 10 to 30 percent on total installed costs as compared to welding, threading or flanging and is now used extensively in many markets. They can be found globally in HVAC, plumbing, fire protection, water and wastewater treatment, oil field operations, mining, industrial processes, power plants, military and marine systems, and other demanding fluid-handling applications.

The method has not only stood the test of time, but has been used in some of the most innovative engineering projects in recent years. Grooved mechanical products are used in the Olympic Stadium in Beijing, the Burj Khalifa in Dubai and the All England Lawn Tennis Club centre court at Wimbledon. In South Africa they can be found in projects as varied as Boschman’s Colliery and the Springbok water by-pass pipeline.

A mechanical joint consists of four elements: grooved pipe, the coupling housings, a pair of nuts and bolts and the rubber gasket. This 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 pressurized.

Couplings fall into two categories: flexible and rigid. Rigidity is achieved with rigid couplings. The unique angled pad design provides positive clamping of the pipe to resist torsional and flexural loads. Flexible couplings allow controlled angular, linear and rotational movement, which accommodates pipeline deflection as well as thermal expansion and contraction.

Both types of couplings provide the security of full circumferential engagement of the coupling into the groove for high pressure and end load performance.

The grooved-end products comprise a complete system that includes, besides rigid and flexible couplings: adapters, valves, fittings, gaskets, tools and accessories. The system accommodates most piping materials, including lightwall, standard and extra-heavy steel, stainless, aluminium, PVC, ABS and plastics, as well as FRP and high-density polyethylene (HDPE). Products come available in various sizes, ranging from ¾-60” (20-1525 mm).

Grooved mechanical pipe joining systems can achieve working pressures of up to 4,000 psi / 276 bar depending on coupling style, pipe diameter and wall thickness. With correct gasket selection, systems can handle temperatures from -34 °C up to 121 °C, making grooved products ideal for HVAC as well as industrial markets.

System advantages

The grooved system delivers numerous benefits - the system provides a union at every joint for ease of system maintenance and expansion – plus enhanced design versatility to allow rigidity and flexibility throughout a system. A mechanical joint also provides noise and vibration attenuation, seismic relief, and accommodates thermal expansion and contraction.

The anatomy of a grooved mechanical joint

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8 Volstruis StreetRant-en-DalKrugersdorpGautengTel: +2782 963 3667www. victaulic.com

The use of flexible couplings reduces the transmission of stresses through a piping system, while the gasket dampens vibration. When flexibility is not desired, rigid couplings can be used. Both flexible and rigid couplings provide discontinuity at each joint, which helps minimize pipeline stresses.

In addition to increasing installation speed, reducing the need for hotworks brings greater onsite safety. As a flame-free method, grooved mechanical pipe-joining removes the many health and safety concerns associated with welding. It eliminates the risk of fire and the need for special fire safety precautions during installation and maintenance.

Hazards caused by compressed gases and welding equipment leads are also eliminated and because no electricity is used in the joining process, energy consumption and costs are reduced. The method causes zero emissions: pipe fitters – and other workers - are not exposed to toxic fumes, which can cause serious health problems.

In addition, grooved mechanical pipe joining systems are manufactured from 90% recycled parts and install rapidly using only hand tools, whilst enabling more convenient maintenance, greater efficiency and lower operational energy requirements

Roll grooving explained

The preparation method most commonly used today in mechanical piping systems is cold forming a groove onto the end of a pipe. This method – known as roll grooving - was invented in the 1950s and is used on 90 per cent of grooving applications. Fast and clean, it is suitable for a wide variety of pipe sizes and standard wall thicknesses. Roll grooving is suitable for carbon steel, stainless steel, copper and aluminium pipe or tubing.

With pipe that is roll grooved, any potential increase in pipe hardness, reduction in tensile strength or reduction in elongation has no effect on the integrity of the joint. Pipe material changes are comparable to any other cold-forming manufacturing operations.

Of course when it comes to specifying systems, reliability is a top priority for engineers.

Mechanical grooved pipe joining has been a reliable and rugged component of a wide range of mission-critical applications, including data centres and flammable chemical cleaning. It has also met the rigorous system demands required for high-pressure performance in power applications and in hydraulic elevators.

System behaviour is very similar to welded or flanged systems, with all piping remaining in strict alignment and not subject to deflections during operation. This makes grooved systems ideal for use with pumps and valves, or where rigid pipe runs are critical. In addition, flexible mechanical couplings provide a natural solution to noise and vibration attenuation, removing the need for additional flexible connections around pump sets.

Tests have also shown that grooved piping systems – using a combination of flexible and rigid couplings – have advantages over traditional joints in seismic conditions. Rigid couplings offer strength whilst flexible couplings can bare deflection and move with pipes, which reduces damage from vibration. These same qualities make them also highly suited for accommodating sway in tall buildings.

And because mechanical piping systems require no flame for joining, there is greatly reduced risk to surrounding workers onsite, and nearby work can continue during installation. There are fewer injuries, business risk is minimised, and insurance costs and chance of potential litigation are lowered. Being substantially faster, exposure is reduced as well.

Cut grooving removes less metal, to less depth, than threading, thus maintaining pipe integrity.

Grooved piping systems have a union at every joint for flexibility and ease of maintenance.

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8 Volstruis StreetRant-en-DalKrugersdorpGautengTel:+2782 963 3667www. victaulic.com

Works worldwide

Mechanical grooved pipe joining has been proven through research, testing and extensive evaluation. It has proven its worth in some of the most impressive global engineering feats including the Hoover Dam in the United States and the Alexandria Library in Egypt.

Grooved systems are verified by independent approval agencies worldwide including Factory Mutual Approvals (FM), Lloyd’s Register of Shipping, Loss Prevention Certification Board Ltd. (LPCB), Underwriters Laboratories Inc. (UL), American Society of Mechanical Engineers (ASME), and many more. These are the same agencies that recognise welded, flanged and threaded systems.

Confidence in grooved mechanical piping systems comes from more than 85 years of research and development, exhaustive field observations, and extensive independent and manufacturer testing. Correctly used and installed, the products are safe and effective.

Engineers can be assured that grooved technology has been robustly tested in the laboratory as well as in the field to demonstrate its consistent strength and reliability. Details about the grooving process, the strength of grooved pipe, and flow characteristics are further explained in published reports from independent agencies.

Also, both static and dynamic post-manufacturing tests are conducted to assure adherence to quality standards. Continuous test loops simulate extended-life conditions at varying temperatures, while regular hydrostatic testing of production samples ensures top-quality standards are being met.

The pressures being placed on building and plant construction may be increasing, but accelerated schedules are also an opportunity for project managers and contractors to look at alternatives to the traditional time-intensive welded pipe.

Coupling and fitting sizes range from 25mm to 1525mm, with its latest product, the new Advanced Groove System (AGS), accommodating sizes 350mm – 1525mm.

The All England Lawn Tennis Club centre court at Wimbledon featured Grooved mechanical pipe joining systems components in its revolutionary retractable roof.

Mechanical pipe joining offers quick, easy and safe installation