A Passion For Piping
Of course, in the movie, the customer goes with the higher price and signs the contract with Cher’s father. You may be asking why I laughed so hard. It was simple. The movie director captured the passion plumbers show in selecting their water piping material. (Somebody involved in writing the script must have had a plumber in their family.)
I saw my father show that same passion when I was a kid on the job. I later saw other plumbers express this passion. Now when I run into all of you, the passion comes out.
Regardless of what you’re passionate about, there is no perfect water piping material. Like the movie, we have three primary water piping materials that account for 90 percent of the marketplace: Copper, CPVC and PEX.
Let’s review the high points and the problem areas of the three piping materials:
Copper: The leading water piping material remains copper. It has been that way for almost 50 years. There are still jurisdictions that don’t permit plastic pipe for water piping material. Heck, the Uniform Plumbing Code still doesn’t directly approve the use of PEX.
On the benefit side, copper is nice to work with, it is easy to join by soldering, it is rigid and strong, and it has a reputation as a material you can trust. You can continue this litany of accolades in support of copper tubing. But to properly analyze a material, you need to look at the limitations and the negatives, too.
Copper tubing has come under attack from a health standpoint. It first started with lead solder joints. Environmental protection groups complained about 50–50 tin/lead solder. Heck, I always used 40–60, which had 10 percent more lead. The initial response was to switch to a 95–5 solder. This was a dumb response, since 95–5 has to be one of the worst solders you could ask a plumber to use. I am amazed that there are still plumbers out there using 95–5. If you are one of them — change, and change now!
The replacement solders are far superior to a lead base solder and light-years ahead of 95–5. The only problem is that the replacement solders require a higher melt temperature than 60–40.
The other health problem associated with copper tubing is the concentration of copper that the tubing adds to the drinking water. The new standard regulating material that comes in contact with drinking water is NSF 61. Copper tubing must now meet this standard. There was concern voiced that the material would never pass the stringent tests. However, the tubing can pass the test requirements. One of the fears is that the maximum contamination level of copper may be lowered in the future. If this happens, then copper tubing may be in trouble.
Copper tubing is the noisiest water piping material when it comes to water hammer. The means to solve this problem is to either increase the size of the pipe to reduce the flow velocity or install water hammer arrestors. If you perform the same analysis on CPVC or PEX, they don’t know what a water hammer problem is. When plumbers switch to one of these materials, they apply the same concern for water hammer, when, in fact, there are no concerns. Of the three materials, water hammer only plagues copper tubing.
The copper tubing industry has been recommending lower velocities of flow for water distribution systems. I have always recommended that, for tubing 3/4 inch or smaller in diameter, the velocity should not exceed 5 feet per second. For 1 inch and larger, the velocity can be calculated based on 8 feet per second. The lower 5 feet per second value is based on preventing the erosion of the pipe wall. The copper industry refers to this as erosion corrosion. The higher velocities eat away the wall of the pipe because copper is still considered a soft material.
You may have done some repairs where the copper tubing seems to have pitted along a length of pipe. This is a direct result of too high a velocity in many cases. Another case example would be the pitting of the pipe just downstream of an elbow or a tee fitting. Again, the high velocity probably was responsible for eroding the pipe wall. In most cases, the plumber simply makes the repair. However, the same repair may be necessary in a few years. What should be included in the repair is an increase in the pipe size to reduce the velocity, or the installation of flow restrictors to limit the pipe velocity.
Another corrosion problem relates to the quality of water. Copper tubing is susceptible to high rates of corrosion to certain poor qualities of water. I’m always asked to define the poor qualities of water. That is not easy to do. Water quality is normally related to a number of factors. You just can’t identify one factor. Most areas of the country experiencing water quality corrosion problems know their water is bad.
Sometimes the water quality from the public system changes because of either the water source or treatment method. If the quality changes, so that it is corrosive to copper tubing, this can become a plumber’s nightmare. I have received reports that this has occurred in certain Florida jurisdictions.
Another headache with copper tubing has been the swing in prices. Over the past five years, copper tubing prices have climbed and dropped more than the stock exchange. This makes it difficult to bid a job that may not start immediately.
CPVC: CPVC has always been compared to copper tubing. Like copper tubing, it is rigid, lightweight and easy to install. From an installation standpoint, CPVC can be solvent-cemented faster than copper tubing can be soldered. But, unlike copper tubing, you cannot lay out a job and then go back and make up the joints. With CPVC you make up the joints as you go.
The manufacturers also promote the fact that CPVC is resistant to the corrosive natures of water. Of all of the water piping materials, CPVC can claim the greatest chemical resistance. In pure water systems, where the water will eat away just about every piping material, CPVC is one of the main piping materials. Plumbing engineers will specify this material for ultra-pure water use in washing operations, deionized water systems and kidney dialysis centers.
CPVC can also have higher flow velocities than copper tubing. Flow velocities can be as high as 10 to 12 feet per second. The only problem encountered with the higher velocities is an increase in the pressure loss in the piping system. However, if there is no pressure problem, the higher velocities (smaller pipe sizes) can be utilized.
There are problems, however, with CPVC as well. For one, most plumbing codes do not recognize one-step solvent cement. As a result, you are required to use a primer to make the joints. While this is ridiculous, it is part of the politics of plumbing codes.
A mistake that manufacturers have made is the development of a sizing scheme called “CTS,” which stands for “copper tube size.” Rather than creating their own pipe size, CPVC just copied the sizes of copper tubing. The reason I call this a mistake is that the wall thickness of CPVC is much greater than copper tubing. Hence, the inside diameter is smaller. Flow water at the same velocity, and more water comes out of copper tubing than CPVC. But, remember that CPVC can flow at a higher velocity than copper tubing.
Problems that relate to the material being plastic include pipe dope, female threaded connections and hanger spacing. If the wrong pipe dope is used on a CPVC thread, the pipe develops a crack in a short period of time. In a test I did, oil-based pipe dope created a crack in a fitting within three days. Most manufacturers go so far as to say to use only teflon tape. If you use pipe dope, it has to be specifically designed for use with CPVC.
Female threads have been a problem with the overstressing of the pipe joint. You will notice that any CPVC female adapter has a thermal rubber ring at the base of the thread. The gasket is what makes the joint. Plumbers, finding slight leaks in a threaded connection, have been known to put all of their force into tightening the joint. This overstresses the fitting, and again, can result in a crack. In one of my experiments, the overstressing of a female joint resulted in a nice large crack after a period of six months. The crack was larger than the crack from the oil-based pipe dope.
As far as hanger spacing is concerned, hangers have to be spaced at 4–foot intervals on horizontal runs of pipe. This is closer spacing than copper tubing.
The only health concerns associated with CPVC comes from the solvent cement. Plumbers complain of cheap highs when they are using the solvent cement in tight locations without ventilation. Additionally, skin is not supposed to be continuously exposed to CPVC. While all of the manufacturers recommend the use of gloves when using solvent cement, many plumbers have no protection for their hands. It is almost a badge of honor to sit watching television at night while you peel the solvent cement from your hands. Every plumbing contractor should have a program whereby they insist that their plumbers wear gloves and eye protection when solvent-cementing plastic pipe.
PEX: Although it’s the new kid on the block in the United States and Canada, PEX has been used for many years in Europe.
You normally hear that there are two methods of making PEX tubing. You may hear that there are four methods. The fact is, there are many methods of making PEX. The industry identifies four categories that these manufacturing methods fall under. Most of the PEX in the United States falls into one of two categories.
I can never keep one method from the other straight. All that matters is that the pipe conforms to the standard for PEX tubing. Twenty years ago, did you care whether galvanized steel pipe was made by the CW, ERW or seamless method? Of course not, all you cared about was that it met the standard for galvanized steel pipe.
I won’t enter into the debate of which cross linking method is best. The only thing that you need to realize is that all of the methods are acceptable in the ASTM standard.
The major difference between PEX and both copper and CPVC is the flexibility of the material. PEX is flexible enough to exercise all of the installation practices of a flexible piping material. PEX’s flexibility also allows the flow velocity to be the highest of all of the piping materials. PEX can always accommodate a velocity of 12 feet per second. Again, raise the velocity and you increase the pressure loss. Most contractors avoid high velocities when the pressure is marginal.
To many plumbers, the biggest problem with PEX is cosmetic: It looks like spaghetti all over the place. We are so trained in the quality and craftsmanship of our work, that we hate to see an ugly looking piping installation. On the flip side, when the walls are up, nobody is going to see it. Electricians have been getting away with spaghetti-looking installations for years.
Perhaps the biggest problem with PEX tubing is the joining methods. You cannot solder or solvent-cement PEX. The only joining methods available are heat fusion welding and mechanical joints. Heat fusion welding is rarely done, hence, all of the other joints fall into a classification of mechanical joint. The most popular method is some form of insert fitting.
The mechanical joining methods are not interchangeable. You cannot use one manufacturer’s joining method on another manufacturer’s pipe. For example, Wirsbo’s fittings will not work on Vanguard’s pipe and vice-a-versa. Each joining method is tested for a particular manufacturer’s pipe.
The hanger spacing for PEX is the shortest distance of any piping material, 32 inches. The dimension translates to one hanger every two studs or joists when spaced 16 inches on center.
Like CPVC, PEX does not have any problems transporting the poor qualities of water around the country. The only health hazard associated with the material is the brass fittings, since there is lead in the majority of brass. The fittings must conform to the NSF 61 standard, and most manufacturers have already had their fittings certified to the standard.
Manufacturers of both PEX and CPVC publish recommendations to install metallic pipe for the first 18 inches on a connection to a water heater. This always has plumbing contractors wondering whether the material is any good. This 18 inch requirement has no technical basis other than to say that manufacturers are too conservative. The material can easily be connected directly to a water heater. I have seen many perfectly acceptable installations with PEX or CPVC connected directly to a water heater.
When selecting any water piping materials, it is more important to know the positives and the negatives of each product. Don’t overrate one piping material while exaggerating the downfalls of another material. The material you select should perform best for your intended application.