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Joining dissimilar pipe

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This contractor has used a number of SharkBite fittings to transition from copper to PEX to flexible stainless steel hose.

By Leah Den Hartogh

In a world with so many options, it can be difficult to choose what works best for the job. There are many ways to join pipe these days. While some choices may be straightforward, it might not be so easy to determine what type of mechanical pipe joining system to use when joining new piping to existing pipe of a different material.

Should you solder? Use a threaded coupling? What about a press joint? Grooved? The list goes on. Depending on who you speak to, they might give different advice as to which option is the best. Above all, it often comes down simply to contractor preference. “I think that contractor experience in how they define a good installation is going to dictate the type of joining method they prefer,” explains Bill Hooper, regional sales manager for Atlantic Canada at Uponor, Mississauga, Ont. “You’ll see a lot of contractors that really like groove type connectors and then some other contractors in the exact same application would use press.” The contractor might ask themselves “have I been called back” or “have I had leaks on this connection method?” Any contractor will tell you to take the path of least resistance.

Almost every pipe manufacturer makes adapters to connect their pipe system to a dissimilar one. Add to that all the companies that specialize in mechanical pipe joining systems and there are many choices. In addition to contractor preference, things like pricing, speed of installation, tool availability and long-term durability all come into play.

This contractor is installing a PRV valve to copper with SharkBite fittings and then transitioning to PEX with a purpose-made fitting.

For commercial applications, there could be infinite examples of when a contractor has to join different types of pipe. “If you wanted to take a Marriott Hotel as an example. You have to get the water up to every single floor. But, how do they get the water up to the floor? There are generally three different materials you’d use to get that water up – either copper, PVC, or PEX. Then depending on the application, you may choose one or the other. I would see Marriott Hotels with all three depending on the engineer doing the design and the installer installing them.

“Generally, once you get to those floors, you would transition to PEX – almost exclusively now. The transition would be between the riser and the individual floor piping,” explained Wade Peterson, vice president of sales and marketing for HeatLink, Calgary. A contractor might choose to use three different types of pipe because, in past experience, it was a more economical system that worked well. All installers involved in the project must be versed in all connection and transition methods to ensure that the system is still reliable and works well as a unit.

The Victaulic mechanical pipe joining systems originated in the First World War and has evolved continuously to include the ability to join many pipe materials and sizes. Victaulic’s transition fittings for dissimilar materials are quick and easy to use – “literally stab on to the piece of pipe and tighten it up. It’s quicker for the contractor but also it gives them reassurance of a proper install just because it takes a few steps out of the process of the original style technology,” said Brent Burrell, mechanical HVAC plumbing sales specialist for Victaulic Canada, Richmond Hill, Ont.

And today it has become common to prefabricate sections of a piping system out of one material, like welded steel, in the shop and then join them at the jobsite with grooved or other mechanical joints.

These Victaulic transition elbows allow copper and stainless steel pipe to be joined.

Location plays a role

For instance, in terms of safety, a contractor might decide to change piping materials because of the location of the pipe. This might occur if the piping is located up high in the ceiling and instead of having to bring a heavy tool above their head, they can use an option which doesn’t require tools.

“The ability to make a connection without any tools still seems very unique to most in the industry,” said Gordon MacDonald, supervisor of sales support, marketing events and training at Reliance Worldwide Corporation, Vaughan, Ont. This ability to transition from one pipe to another with one fitting and no tools helped make the SharkBite brand name known to the industry, said MacDonald.

Tooling costs may also affect which piping choice is used, and therefore which connections or adapters are required. “If you were to talk to a contractor 20 to 25 years ago and suggested that they have to buy a multiple thousand dollar tool to assemble something when they could use the torch to do the same thing, many contractors at that time would question the value of the investment,” remarked Dale Hanscomb, sales and location manager of building solutions for Rehau Industries Ltd., Burlington, Ont.

“I think with the younger generation coming into the trades, they seem to be more open minded about systems that may require a tool and the potential downside of an open flame. I honestly think that one of the benefits to the tradesperson today is that there are a lot more choices. They can pick the one best suited to their comfort level and experience.”

These SharkBite fittings transition from PVC to PEX.

Maintaining flow

At the most basic level, when connecting two pipes a contractor joins a male thread/fitting to a female thread/fitting or vice versa, but the installer still needs to understand the potential limiting parameters with the temperature, pressure, flow rates, and velocities when choosing a transition adapter to join dissimilar systems.

When connecting two different types of pipe, the installer might also have to mix different connections. This might include welded, threaded, sweat, solder, grooved, press, flange, crimped, or fusion.

Victaulic also offers many transition fittings, a number of which are used in this photo.

For example, there are adapters with a PEX connection of one end and a soldered, threaded, grooved, etc. fitting on the other end. “It’s pretty straightforward, you would buy a PEX adapter for one side, and then whatever you were connecting to on the other side which say was steel pipe – then it would be a threaded adapter typically to a NPT male pipe thread fitting, or a female NPT fitting,” explains Peterson. If the plastic were to connect to copper, then you would typically use a sweat fitting. “You pretty well need an adapter type of fitting to connect dissimilar metal or dissimilar components.”

Even though it can be a bit confusing to an installer about which fitting is best, what it boils down to is what the contractor wants to use or what has been specified for the project. “If an engineer was involved in the specification, they would look at what is existing and try to adapt to that, said Hanscomb.

Each mechanical pipe transition system will have pros and cons. At the end of the day, the installer must be comfortable with the system that they are installing and that they understand. Pick a system that is easy to use, repetitive, provides the flow rates required, and holds up to its environment, suggests Hanscomb.

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