Mechanical Piping Systems: Keeping Your Structure Safe and Maintainable

By Dave Hudson

Piping systems in structures both large and small will nearly always require some degree of system maintenance. The efficiency and life of pumps can be reduced greatly by floating debris in the system, and boilers, water heaters and pressure reducing valves in larger buildings are all subject to wear and tear, increasing maintenance obligations.

Erosion can happen over time in bearings and impellers, requiring pump maintenance. In addition, a piping system would need maintenance or replacement if the lines become corrupt. These concerns are easily addressed in piping systems that have been installed with grooved mechanical pipe joining products, as these products, compared to other joining methods, are inherently easier to work with during maintenance activities.

Periodic inspections, physical changes or expansion to the piping system, as well as unscheduled repairs, are three of the most common types of piping system maintenance. Periodic inspections ensure that the system is intact and that water softeners, filters and water heaters are operating at maximum efficiency. Physical changes are performed to adjust existing installations, replace old piping or expand an existing system. Unscheduled repairs are the most time sensitive, because they usually need to be done immediately and often require a system shutdown.

Grooved mechanical pipe joining systems offer many maintenance benefits, including the ability to reduce unscheduled maintenance time, due to ease of disassembly and reinstallation, as well as improvements in safety, system reliability and reduction of system fatigue. A quick look at the details of a grooved mechanical coupling reveals how grooved mechanical piping systems make piping system maintenance faster, easier and safer than other joining methods.

Grooved mechanical joints

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

Grooved pipe joints can employ one of two basic coupling styles: flexible or rigid. Flexible couplings allow a limited amount of linear and angular movement, while rigid couplings create a rigid joint and do not allow movement, similar to a flanged or welded joint. There are benefits to both styles. A rigid coupling can be used wherever immobility in the pipe joint is needed. Flexible couplings are designed to accommodate piping expansion, contraction and deflection, and thus are ideal as joints around equipment connections, for changes in piping direction and in the building of expansion/seismic joints.

Grooved mechanical systems are available in a broad range of sizes for a wide variety of piping applications; they are most widely used, however, in fire protection, HVAC and plumbing applications including potable water systems, storm water systems, roof drain systems, vacuum plumbing systems and rain, waste and vent systems. Grooved copper systems are most commonly used for joining domestic water systems in 2 – 8" /50 –200mm sized copper tubing. Grooved stainless steel systems offer an alternative to copper in many applications.

Safety

One of the many maintenance benefits of grooved piping is the increased safety during installation and maintenance, decreasing the risks to the contractor and building occupants.

Grooved mechanical piping systems are safer than other pipe joining methods. They enable contractors to assemble piping flame-free within the facility, eliminating the fire hazards typically associated with soldering and brazing. Those methods, like welding, are rife with hazards, including fire risk, electric shock and exposure to compressed gases and toxic fumes. They also require personal protection for the eyes, hands, feet and body. Welding, soldering and brazing also involve many time-consuming steps to join pipes correctly and require a fire watch during these procedures. This can slow the schedule and increase costs.

Because no flame, arc or gases are required to join a pipe with grooved couplings, the grooved system does not require additional man-hours or jobsite preparation and does not introduce toxic fumes to the facility.

Safety on the jobsite is always important; it becomes even more critical, however, during maintenance projects in buildings such as hospitals and schools, which often must remain open and operational during maintenance.

Ease of maintenance

Among the most important benefits of grooved mechanical piping systems is the reduction and ease of maintenance. The design of grooved systems allows for less routine and scheduled maintenance. The C-shaped cross section seal on the gasket is very durable and can handle significant compressive and cyclical loading. Workers can pressurize and depressurize a system repeatedly for many years without fatiguing the rubber. In addition, grooved flexible couplings allow the pipe to move or vibrate within the coupling, which reduces the transmission of noise and vibration from equipment, thereby eliminating the need for rubber bellows or braided flex connectors, which are known to require periodic replacement and can be costly. The grooved flexible coupling attenuates noise without wearing out the gasket.

If maintenance is needed, grooved mechanical systems enable quicker and easier access than other pipe joining methods. The grooved system reduces rework by 10 – 15 percent over soldering and brazing. A coupling provides a union at every joint, which allows easier access to the system as well as the flexibility to expand or reroute the system. To remove the coupling, the worker simply loosens the nuts and bolts and removes the coupling housings and gasket — no torch, saw or flame is required. Once the job is complete, the coupling can be reassembled on the grooved end of a pipe, valve or fitting.

The assembly and disassembly of grooved systems is much easier and therefore requires less labor. It also eliminates the need for complete system shutdown because it does not require torches, and, therefore, the system doesn’t need to be completely drained and dried. This makes it easier for the building to return to full operating capacity quickly and does not disrupt building occupants. Serviceability in tight spaces is also easier and more time efficient with grooved systems, because grooved couplings allow a full 360 degree rotation of the pipe and system components before tightening so that proper alignment can be achieved.

Grooved mechanical systems are a safer and easier alternative to maintaining a building’s piping systems, making the grooved pipe joining method a viable option for projects that would require regular maintenance procedures or where occupants of the building cannot be disrupted for maintenance work. In addition, grooved systems offer ease of access, reduced man hours on the jobsite and less safety risk.

David L. Hudson is a senior engineer for Victaulic Company Inc. He is a practicing mechanical engineer with 30 years of experience. He can be reached at dhudson@victaulic.com.