CPVC for hot water application 1

[MFJewell]

I am planning to reroute some atmospheric drains in our plant. The drains are open floor drains and hubs from a chiller deck. The current lines are 4" cast iron with what looks like leaded joints. I am planning to use CPVC for the reroute. Two of our chillers are steam turbine driven. When they are running they drain cooling water to local hubs. When this happens, I get readings of just over 200 F at the local floor drains. At the piping tie in point (transition from cast iron to CPVC, which is about 100 ft from the hot water source)I get readings of 145 F. The temperature gradient of the pipe is about 200 F down to 85 F over ~ 200 feet of pipe. CPVC is suitable for up to 200 F. I believe I am ok with CPVC. Does anyone have experience that would dictate otherwise?

 

[bimr]

That is a judgement call for you.

You may want to look into the FRP pipes which are capable of handling this application:

[URL unfurl="true"]http://www.smt-epocal.com/document/bondstrand2000m.pdf[/url][/url]

 

[moltenmetal]

This is rule of thumb stuff, based on experience which tempers the claims of the vendors a bit.

CPVC is marginally acceptable at 200 F, and only then in non-pressurized service.

It is acceptable for continuous service at 180 F, but it is pretty soft already at 180 F.

You can use it for (uninsulated) drains to 200 F, but expect to be putting in a lot more support than you're used to, or expect the line to sag significantly between supports- quite embarassingly, actually. Don't ask how I know this...

The largest linesize I'd use CPVC for would be 4". Above 4" I'd be considering other options because sch80 CPVC pipe and fittings get very costly.

Note that PP is good for continuous use to about 225F, with the same caveats. Of course it's not anywhere as easy to work with as CPVC, and has its own list of downsides.

Neither material should be used outdoors without some kind of external UV protection. White mastic is one option, and insulation is the other (but definitely not in your case!).

 

[PEDARRIN2]

Both the IPC and the UPC limit discharge to the sanitary piping to less than 140 F.

FRP is not allowed for drainage in either.

If in IPC area, I would recommend using PVDF, which is rated up to 250 F. However PVDF is expensive.

There are drain tempering valves (

http://www.thermomegatech.com/wp-content/uploads/2014/09/DTV-1.pdf)

are used for this type of application.

 

[MFJewell]

Thanks for the responses. Some additional information, the new lines are indoors so no concern for UV impact and will not be insulated. The high temps are intermittent, we only run the steam turbine driven chillers when we have excess steam supply or need a lot of cooling. During summer time they run about 150 hours per month (~ 5-7 hours per day) and about 20 hours per month during winter time. When the steam turbine chillers are not running, the line temps are only slightly warmer than ambient.

As for high temp discharge to the sanitary, we actually have a lower limit per local municipal code (113 F) at the point of discharge to the sewer. We are well below this number. At the current exit point from the building, the pipe temperature is about 88-90 F.

 

[rconner]

Am curious what is the chemistry of the "cooling water" the drain pipes convey?

 

[MFJewell]

Raw water from public water supply or well water.

 

[rconner]

If you decide not to go with the plastic option, another product/system with greater strength, that can handle UV and quite high water or air temperatures without reduction in strength or stiffness, and that can much reduce support spacing and thermal expansion, contraction and construction issues is ductile iron piping (DIP)see FAQ, "What is the maximum service temperature...?
at

https://www.dipra.org/ductile-iron-pipe-resources/frequently-asked-questions/design)

and e.g. "Case #1 pg 19 as well as general notes pg 7-21 of file at

http://www.american-usa.com/system/assets/335/original/AMERICAN_PIpe_Manual_-_Specials_(4-25-16).pdf

etc. [Just be sure to choose a gasketing and lining system etc. suitable for the temperature and other conditions involved. That is why this piping material has been used for many years for many thermal-related applications, including insulated and non-insulated for district heating and geothermal etc.]

 

[PEDARRIN2]

MFJewell,

I would contact your local plumbing AHJ, because I have seen the "point of discharge to the sewer" be interpreted two ways.

1. Where the building sewer connects to the municipal sewer. It would be very easy to meet this interpretation.
2. At the waste receptor, i.e. floor drain. You would not meet this interpretation.