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CPVC Failure

14K views 38 replies 12 participants last post by  Plumberman 
#1 ·
About 2 1/2 years ago my company re piped about 200 ft of heating water supply and return underground with 6'' CPVC. We have had nothing but problems out of it. We have made numerous repairs of couplings and 45's It got so bad that we replaced the whole run, again it leaked. The glue joints are breaking. Had it tested by the glue company and by the manufacturer. They both blame each other. I am beginning to believe its something in the ground reacting with the chemical and the glue. Some of the fittings have blown completely off after months of being in service. Needless to say we are at our wits end and no one has any answers. I voted that we tear it all out and go back with steel, which is what they had in the first place. Electrolysis reeked havoc on the steel before. That's why they chose CPVC. Anyone ever ran into this?
 
#2 ·
Think I answerd my own question....

No allowance for expansion- CPVC has a greater thermal coefficient of expansion than other materials a plumber has traditionally used. In other words, it will expand more when used in a hot water application than other materials, such as copper. If this characteristic is not considered in the design and installation, disastrous results can ensue. CPVC expands 4.7 inches per 100 feet for every 100 degree Fahrenheit rise in temperature. In a multi-story building where long runs of piping are common, it is especially important to allow for this expansion. Every straight run of pipe must be provided with a properly sized and supported expansion loop. The expansion loop will absorb the deflection resulting from thermal expansion of the pipe. In the absence of the expansion loop, the expansion of the pipe will stress the fittings to the point of failure.
 
#4 ·
I didnt know that CPVC expanded at 5 in per 100 ft for every 100 degree rise. The run is well over 200 ft. This has to be the problem. They are running their heating water at about 130 to 135 degress. The hottest they run is 140.
 
#5 ·
Regular PVC has similar results, poly vinyl chloride in states like Illinois is a self destructing sytem because of the temperature changes, this was revealed ten years after the product came into general use, but by then it was too late, and companies worked on coming up with ways to compensate for the product defect, like using mechanical expansion joints.
 
#8 ·
This is Sch 80 CPVC. Everything I have read up on suggest that expansion loops are a must. And glycol based chemicals reek havoc on the glue joints. There ARE NOT any expansion loops in this system which is underground and they run glycol through their system
 
#19 ·
I've installed expansion joints for all kinds of DHW systems and a few process systems. Used PVC for water services even, but I've never put an exp. jt. in on the PVC. Do I start to sweat this or what. I'm thinking not due to the avg. water temp. of the gnd water hear @ 77 F.
 
#21 ·
Any piping used for heating, that is buried in the ground is going to give you a problem. There is no room for expansion and contraction with the earth holding it tight in place.
I would try installing the lines in a bigger concrete utility pipe using the utility pipe as protection and with room for movement.
Thats why they make concrete tunnels for steam lines that go under ground, buildings,etc.
 
#22 ·
There is a seperate glue company from the manufacturer of the pipe?

With Ipex for example, I'm pretty sure they make their own glue.

When you talk about expansion joints - are you talking about expansion loops (4 - 90's), or expansion joints like the ones that basically look like a bushing, a coupling, a reducing coupling, another bushing, and then a piece of pipe, and then a coupling types (ones I've used from Ipex on their Corzan CPVC).
 
#26 ·
There is a lot being used around here ( Wash. D.c. Area) . To be honest I have seen quite a bit that has been in a while and haven't seen many problems at all .

Still like copper .

Cal
 
#31 ·
This is disheartening news. I recently installed at one of my schools an 80 foot supply and return run of 1-1/2" cpvc heating pipe underground between buildings and all I used was thermocell insullation and some sand backfill. It replaced rusted out steel pipe. I hope I don't have any problems. This was 6 months ago. I bought it from Ferguson and did some research to see if it was up to the application. The sales rep said it would be fine. We shall see.:whistling2:
 
#37 ·
This is disheartening news. I recently installed at one of my schools an 80 foot supply and return run of 1-1/2" cpvc heating pipe underground between buildings and all I used was thermocell insullation and some sand backfill. It replaced rusted out steel pipe. I hope I don't have any problems. This was 6 months ago. I bought it from Ferguson and did some research to see if it was up to the application. The sales rep said it would be fine. We shall see.:whistling2:
It probly is, the problem that we were having was both boilers running at the same time in excess of 140 degrees. They also have an outside air sensor, to save on energy costs. When it is warm the boilers dont run as much, and our weather is crazy down here in the winter. It might be 70 for two days the drop to 20 for three. This is where all the expansion and contraction was taking place. It actully pulled the pipe out of the fittings because it moved so much, also the glue that was used wasnt bonding to the pipe as it should....
 
#36 ·
Not many homes here with Pressure reducing valves, by law city cannot exceed 90 psi. For homes equipped sure thermal expansion devices could absorb it, but I think even in the normal operating ranges that are materials here on the pennissula aren't accostomed to. I can't remember having a temp swing in 2 days of 35- 40 since I lived in NY. Maybe it's just a phase but sure seems like alot. Who really cares, I'm working:thumbsup:
 
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