Ideal Pipe Joining [Mar 2012]

March 22, 2012 5:52 am

During the World War I, mechanical pipe joining was invented by the company now known as Victaulic. Since being made commercially available in 1925, it has become a preferred joining method on many piping applications.  Yet many myths and misunderstandings still exist.  In this article, Pankaj Soni, Victaulic Country Manager – India assesses the technology and its durability
Mechanical grooved pipe joining has been proven through research, testing and extensive evaluation. During its 85-year history, it has stood the test of time in some of the most impressive engineering feats including the Hoover Dam in the United States, and the All England Lawn Tennis Club centre court at Wimbledon, where the state-of-the-art retractable roof over the centre court used grooved technology for the heating and chilled water piping systems in the first project of its type in the world.
Recent work in India, where Victaulic has been operating for nearly five years, includes the fashionable Park Hotel Hyderabad, the Delhi Airport Metro Express, Mumbai Airport and the ICC Marriott in Pune.
Grooved mechanical pipe joining provides an attractive alternative to welding and flanging for engineers, owners and OEMs.  It allows quick, easy, safe installation and maintenance to meet compressed project schedules and reduce labour costs, 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. 
For these reasons more and more OEMs are beginning to manufacture products with grooved ends, as they realise the considerable advantages this gives their own equipment.
For instance, manufacturers of pumps and other related types of equipment have come to realise the advantages of grooved technology, and many now offer a grooved outlet as a standard option. Not only does it make for easier product testing in the factory, but manufacturers know that having a grooved connection reduces the likelihood of additional forces on the equipment that could damage it.
The groove in actionMechanical pipe joining systems comprise of bolted couplings and a gasket seal which engage into grooved pipe without the need for hotworks. Whilst the technique may be relatively new in India, elsewhere this is not the case. Victaulic invented the system over 85 years ago and has continuously made pipe joining faster, easier and more economical with its unflagging focus on quality, research and development, and product innovation.
In addition to increasing installation speed, reducing the need for hotworks brings greater onsite safety, slashing risks, delays and the need for catch up, and also cutting energy consumption and harmful onsite emissions. Victaulic products are manufactured from 90 per cent recycled parts and install rapidly using only hand tools, whilst mechanical couplings enable more convenient maintenance, greater efficiency and lower operational energy requirements.    
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 of the joint allows rigidity and flexibility throughout a system. A mechanical joint also provides noise and vibration attenuation, seismic relief, and accommodates thermal expansion and contraction.
A mechanical joint consists of four elements in total: grooved pipe, the coupling housings, a pair of nuts and bolts and the rubber gasket ring. 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 pressurised.
The flexibility of Victaulic flexible grooved-pipe couplings reduces the transmission of stresses through a piping system, while the gasket damps vibration. When flexibility is not desired, rigid couplings can be used. Both flexible and rigid couplings provide discontinuity at each joint, which helps minimise pipeline stresses.
Roll grooving The preparation method most commonly used today in mechanical piping systems is cold forming a roll groove onto the end of a pipe.
This method – known as roll grooving – was invented by Victaulic 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.
The latest development in grooving technology for medium to large-diameter pipes is the Advanced Groove System (AGS) from Victaulic. Suitable for sizes between 350mm and 1525mm (14 – 60”), AGS offers enhanced strength and reliability through a more robust coupling housing and a patented wedge-shaped roll groove, which results in a 40 percent increase in end-load carrying capabilities compared with previous joining methods.
Does grooving weaken the pipe end? Grooved 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, the availability of flexible mechanical couplings in the Victaulic product line provide a natural solution to noise and vibration attenuation, removing the need for additional flexible connections around pump sets.

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