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Grooved Mechanical Pipe-Joining Systems: Boosting the Bottom Line

By Dave Hudson, Victaulic

Grooved mechanical piping systems have been changing the way contractors do business for more than 85 years. In its nearly century-long existence, grooved piping has become the preferred pipe-joining method for installing commercial HVAC and fire protection systems, and an increasingly popular option for installing plumbing and other piping systems within commercial buildings. Despite its history, the pipe-joining method is still misunderstood by some in the commercial building industry. It’s time to demystify the method.

Benefits to contractors include ease and speed of installation, reduced total installed costs, safer installations and ease of system maintenance and expansion. The multiple benefits gained through the use of grooved piping products can easily become a competitive advantage for contractors and a boost to their bottom line.

Contractors can benefit from the simplicity and reliability of grooved piping. The four elements of a grooved mechanical pipe joint are the grooved pipe, a gasket, the coupling housing, and nuts and bolts.

The pipe groove is made by cold forming or machining a groove into the end of a pipe. A gasket encompassed by the coupling housing seals around the two ends of the pipe, and the key sections of the coupling housing engage the groove. The bolts and nuts are tightened with a socket wrench or impact wrench. In the installed state, the coupling housing encases the gasket and engages the groove around the circumference of the pipe to create a leak-tight seal in a self-restrained pipe joint.

Grooved pipe joints utilize one of two coupling styles: rigid or flexible. Rigid couplings produce a rigid joint and do not allow movement. They can be used wherever immobility in the pipe joint is needed, similar to a flanged or welded joint.

Flexible couplings allow a limited amount of linear and angular movement. They are capable of handling thermal expansion and contraction, deflection, differential settlement between structures and seismic movement. They can also attenuate noise and vibration. As such, flexible couplings are ideal wherever movement is likely, such as joints around equipment connections, changes in direction and building expansion joints.

Flexible couplings played an important role in constructing London’s Wembley Stadium. The 90,000-seat venue with sliding roof will be the largest host of the soccer tournament at the 2012 London Olympic Summer Games. To accommodate the retractable roof design, the project team required a piping solution capable of handling the potential movement. The Victaulic grooved system was chosen for chilled, condenser and heating water lines due to its ability to accommodate for thermal movement as well as building movement. In addition, the use of flexible couplings enabled the design team to layout the piping to follow the curvature of the stadium.

Although the upfront materials cost of a grooved mechanical piping system may be greater than other pipe-joining methods, grooved systems offer a reduction in total installed costs because they reduce labor time, which is the largest cost variable in the field for contractors. Victaulic estimates show that jobs requiring welding applications demand up to 45 percent more man-hours on average over grooved piping solutions, and at a much higher labor rate.

Managing construction schedules and meeting deadlines are critical elements directly linked to project success and profitability, especially when schedules are tight and deadlines are paramount. Contractors can help their bottom line and competiveness with the ease and speed at which grooved mechanical piping systems are installed.

Standard grooved couplings are up to five times faster than welded joints and up to three times faster than flanged joints to assemble. Joining pipe with a grooved mechanical coupling is much faster than welding because the gasket and coupling housing simply need to be positioned on the grooved pipe ends, and the bolts and nuts tightened with standard hand tools. No flame, heat or specialized tools are required during installation.

In addition, most grooved systems can be visually inspected following installation. Metal-to-metal bolt pad contact confirms that the mechanical grooved coupling has been properly installed and secured into place. Welding, on the other hand, often requires X-ray inspections to ensure a sound joint, increasing both time and costs.

The combination of grooved piping systems’ simplicity of installation, elimination of hotworks, and ability to construct in any weather condition offers a dramatic reduction in the construction schedule and project calendar days.

Injuries pose a significant cost to contractors. Failure to maintain a good safety record increases costs and reduces business opportunities. As a flame-free joining method, grooved mechanical piping is one of the safest ways to connect piping systems because it eliminates the fire and fume hazards typically associated with welding. Welding is one of the most dangerous industrial activities. Its hazards include fire risk, electric shock and compressed gases, exposing workers to noxious fumes and particulate matter, as well as potential burns and eye damage.

In addition, welding activities require a fire watch during and following work, which can slow the construction schedule and increase costs. Welding risks are a greater concern during expansion and/or retrofit projects during which buildings such as hospitals, schools and apartments may remain open and operating. Grooved mechanical pipe joining can decrease the risks to workers, building inhabitants and onsite employees.

Maintenance concerns are easily addressed with grooved mechanical pipe-joining systems. With a union at every joint, grooved piping systems enable quick and simple routine maintenance, system expansion and retrofits. A service worker simply loosens two nuts and bolts and removes the housing and gasket to access a system. A flanged joint, with its multiple bolts, is tedious and time-consuming to disassemble and then reassemble. Even more cumbersome, a welded joint would need to be cut to provide access to the system, exposing the worker to safety hazards similar to those encountered upon initial assembly.

Contractors have made the switch to grooved mechanical piping for countless reasons, including the benefits to their bottom line, increased safety for their employees and others, ease of installation and maintenance, and the long-term life of the system.

In addition, grooved mechanical piping holds a place in many contractors’ toolkits due to engineering benefits such as accommodation of thermal expansion and contraction, deflection and seismic movement, and noise and vibration attenuation. In short, grooved mechanical piping leads to successful builds and projects.

About the Author
David L. Hudson is a senior engineer for Victaulic Company, Inc. He is a practicing mechanical engineer with more than 31 years of experience. He can be reached at dhudson@victaulic.com.