New Kid On The Block

There is a great scene from the movie Moonstruck where Cosmo Castorini, a New York City plumbing contractor, is giving a young professional couple an estimate to re-pipe their aging bathroom. They initially balk at the seemingly exorbitant quote, but Cosmo is unfazed, he expects this kind of response. He looks at them with a grave seriousness and says:

“There are three kinds of pipe. There’s the kind of pipe you have (galvanized) and that’s garbage, and you can see where that’s gotten you. Then there’s bronze, which is pretty good, unless something goes wrong, and something always goes wrong. Then, there’s copper, which is the only pipe I use. It costs money. It costs money because it saves money.”

Cosmo, played brilliantly by Vincent Gardenia, delivers his pitch not just with his words but also with hand motions as skilled and precise as a symphony conductors’. He is well practiced and very effective and the husband quickly agrees to go along with Castorini’s recommendation. 

Moonstruck came out the same year I got married, and I remember going to see it with my wife. That scene really had little or nothing to do with the main plot of the movie, but it has always stuck with me, partly I am sure because I was a young plumber at the time. I remember laughing back then and somewhat scoffing at the notion that any real life plumber would ever be faced with a choice of what material to use for water pipe. At that time, in my mind at least, the only real choice we had to make was type “L” or type “M”?

However, a lot of things can change in 25 years and if Castorini were to deliver his pitch today he would have to add a few more options to his list and come up with some additional hand flourishes. Today copper and PEX (crosslinked polyethylene) battle it out for water pipe supremacy, with CPVC (chlorinated polyvinyl chloride) also vying for a slice of the pie. There is quite a debate raging on which is material is best. Do a Google search and you might be surprised to learn just how deep the passions run on all sides. I am not about to enter into that debate, rather I would like to take a look at yet another option that has recently arrived on the scene: flexible corrugated stainless steel tubing (CSST) for potable water lines.

CSST is probably familiar to most readers as it is the same tubing that has been used for quite a few years as an option for natural gas pipe. The gas pipe version is typically wrapped in a yellow polyethylene jacket. Over the past few years I have seen CSST being marketed for use in quite a variety of applications, such as insulated line sets for solar collectors, flexible connectors for hot water tanks, and as an option for piping closed loop heating systems. Even more recently, at least one manufacturer I am aware of is offering CSST for potable use. The tubing, which is manufactured with grade 304 stainless steel is available in pipe sizes from ½-in. through to 1-¼-in. internal diameter and is available plain or with red or blue polyethylene jacketing. A full range of fittings seem to be available for sizes from ½-in. to 1 in., but for the 1-¼-in. pipe size straight adapters are available but no elbow or tees. All tubing and fittings are certified by IAPMO to be NSF/ANSI 61 compliant for use in drinking water systems and are CSA approved.

Does the plumbing world need another tubing option for potable water lines? Let’s have a closer look and see what advantages are offered by CSST. To me, the most obvious advantage CSST has over a rigid piping system, such as copper or CPVC, would be ease and speed of installation. The tubing is available in coils up to 150 ft. long, and a full coil of one-inch tubing weighs just 29 lbs. In this way, CSST would be very similar to PEX; and like PEX, the flexibility would eliminate the need for most elbows, substantially reducing the total number of connections required. Unlike PEX, there are no specialty tools required to install or connect CSST. The tubing is cut with a standard tube cutter and the fittings use a hex nut over a nylon isolation ring and a silicone sealing ring. CSST is also suitable in applications where higher temperatures may be an issue, which is why it is a popular choice for solar supply lines.

One question that is raised deals with pressure drop. The corrugated construction could lead many to believe that the CSST would have a much greater pressure drop than smooth walled copper or PEX tubing; however, independent testing indicates that this is not a concern. The Canadian sales representative commissioned this test and the results show that ¾-in. CSST performed very well and had a pressure drop very similar to copper at various flow rates, and outperformed crimp style PEX which had a higher pressure drop at the same flow rates. The testing apparatus which was on display at the recent CMX show had identical length runs of ¾-in. copper, CSST and crimped PEX each with four 90-degree bends hooked up to multi speed pumps to achieve the various flow rates. I emphasize that the PEX in the test model was crimp style since the PEX that utilizes an expander tool and larger fittings would also have lower pressure drops.

Ultimately, it will be up to the marketplace, and of course, the Cosmo Castorinis of the world to determine if there is a place for yet another potable water tubing system. In my mind, the more choices that are available the better. As I said earlier, the debate about what is best will go on and on. CSST perhaps offers a faster, easier option for the copper purists out there who just do not want to accept any plastic options. <>

Steve Goldie worked as a plumbing and heating contractor for almost 20 years before joining Noble as manager of its heating department. In his current position, Goldie focuses on product specification and system design solutions. He can be reached at sgoldie@noble.ca.