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Winter testing of PVC

Darren Emery

Darren Emery

Registered User
Joined
Oct 20, 2009
Messages
503
Location
Manhattan, Ks
This question comes up every winter, and I'm wondering how other cold weather jurisdictions handle it. New commercial construction, no water to the site yet, plumber calls and asks for permission to use air on the PVC underground.

They can tank in water with a little more effort, but the plumbers still really resist water in winter (my p-traps will freeze!) I've never seen PVC shatter - but have heard more than one horror story (all second/third hand though. Anyone actually been around a site that the PVC exploded?)

How does this get handled in your area?
 
We still allow the air test........have not seen any explosions, seems like 5 psi would to low to cause problems, but like you have heard "stories".

I used to work in a wood shop that we plumbed in air lines around perimeter of shop, couple hundred feet of 1" schedule 40 that was under constant pressure of 100-125 psi, as far as I know it's still there, that was about 15 years ago.
 
It never gets that cold here, so frozen water isn't an issue. I have seen plenty of PVC under an air test and have never experienced a ruptured pipe. The usual scenario is that I show up for inspection and the pipe has 5 or more psi. Nobody asked beforehand and that's when I tell them that an air test isn't allowed. They already knew that but the pipe might be 8" dia. and 400' long, so the waste of water and the fact that once the weenie is pulled, the water is trapped, is their reason for the air test. So there we are with the test holding air and they ask if I insist on a water head test. I never have and tell them to release the air while I am there.

If someone asks beforehand, my answer is: Air test is not allowed.
 
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If the someone calls first, my answer is no air test allowed.
Click to expand...
Same here. We do not give permission to use air but when we show up and that is what was used we go forward with with the inspection.

They can always drain the system and install RV antifreeze in the traps after the test.
 
The danger is exposed PVC could shatter and project shrapnels. Manufacturer and code allows DWV testing of 5 psi but apparently does not provide a maximum threshold above this tolerance.

I think since yours in this case on underground plumbing the threat of injury is reduced except for the portion that is exposed. Accepted practice allows an outer sleeve or pipe over the exposed portion to protect bystanders from potential harm.

Most the recorded incidents have occurred where PVC was used to transport compressed air or gases and fatigue or contamination cause the pipe to burst. The story I heard is it was during freezing weather the PVC is very brittle and hit by a sharp blow causing injury to the hands.
 
As a side note, I have applied 100 psi to 3" sch40 pvc without failure. I certainly do not support it, but it was for an air cannon. It also was not cellular core pvc either.
 
Builder Bob said:
.......Supply and distribution piping can be tricky. .......
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Most PEX manufactures will allow an air test up to 100 PSI

PRESSURE TESTING AND INSPECTION*

​
• Test system with water.• Test pressure shall be at least equal to the expected workingpressure (main pressure), but not less then 40 psi and notgreater than 225 psi at 73°F.• Compressed air testing is only recommended when wateris not available or when cold weather could freeze thesystem. Compressed air tests shall include appropriatesafety precautions and the test pressure shall not exceed100 psi. PEX tubing is ductile and will not shatter during apressure test and release shards of plastic. However, plasticfi ttings or other system components, or unassembled fi ttings,may cause a hazard. Check with local codes before usingair pressure testing.• Test duration should not be less than 15 minutes.• Do not allow water in systems to freeze.

​
*Source: DESIGN GUIDE Residential PEX Water Supply Plumbing Systems,Prepared for PPI, PPFA, & PATH by NAHB Research Center, Inc.,

​
November 2006

 
mtlogcabin said:
Most PEX manufactures will allow an air test up to 100 PSI
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When I read the first sentence I thought it was a joke.

Then I read the PEX blurb and there it is, 100 PSI.

Then they qualify the statement by telling us that they don't trust the fittings.

Turns out, it was a joke.
 
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I worked in a woodshop that ran a twin stage compressor on pvc. We were running about 150 psi when it blew, it was unheated and winter. A javelin about 6' long was lodged in the ceiling. They were fitting black iron the next day.

I've seen plumbers run PEX to 90 to test it, I don't see a point in much more than that.
 
* * * *

From the 2006 IPC,

SECTION 312 TESTS AND INSPECTIONS

312.1 Required tests.

The permit holder shall make the applicable tests prescribed in

Sections 312.2 through 312.9 to determine compliance with the

provisions of this code.........The permit holder shall give reasonable

advance notice to the code official when the plumbing work is

ready for tests........The equipment, material, power and labor

necessary for the inspection and test shall be furnished by the

permit holder and the permit holder shall be responsible for

determining that the work will withstand the test pressure

prescribed in the following tests.......All plumbing system piping

shall be tested with either water or, for piping systems other

than plastic, by air........After the plumbing fixtures have been

set and their traps filled with water, the entire drainage

system shall be submitted to final tests........The code official

shall require the removal of any cleanouts if necessary to

ascertain whether the pressure has reached all parts of

the system.



Testing by air is a "no-no" on the Commercial DWV system!

From the Charlotte Pipe And Foundry Company - [ one manufacturer

of pvc pipe ]:

http://www.charlottepipe.com/Documents/PL_Tech_Man/Charlotte_Plastics_Tech_Manual.pdf

See Page 104 from their Installation Manual.

No testing by air!



* * * *
 
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If the plumber is worried about freezing tell him to surge it with air after test, should remove any remaining water or most of it.
 
We are in a cold area and use nothing but ABS for dain lines and I have only seen one water test. When I was installing plumbing we would test with air all the time. On a side not we do test PVC with air but it is for the furnace flue piping to make sure that it is holding. 5 pis for 15 min works for me.
 
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I wonder what your experiences has been in regard to finding leaks from pressure test?

Most of the leaks on rough-ins have been from bladders leaking down and loose clamps on Fernco caps; a few damage pipes and leaking joints; but it seems the majority of leaks occur after the test from impact damage, overzealous nailers and forgetting to glue tail ends.

north star I forgot about the IPC and IRC differences.

Francis
 
I remembered a plumber called and wanted to know if I needed to re-inspect a pressure test after he replaced the piping when he forgot about leaving the water in over a weekend when it froze!

Another time I had passed the pressure test but the nail plates were not in place and tagged it and noted approved the pressure test. Went back and notice some of the piping had been spliced where the new plates where installed at the sole plate; a newbie had installed the plates with the narrow end up and nailed through the pipes.

I’m sure there is a lot more.

Francis
 
I agree with MTLOGCABINS approach in post #4 plus I believe the 2009 IPC section 312.3 allows this. Many simply spend way to much time "what if" with these codes. I have found over the last 17 years to simply read the code text and do not put any more, or take any less out of it. Merry Christmas to all!!!
 
Francis #17 post, I'm in agreement with the issues you have stated in regards to several reasons for test failures.

In another muncipality that I worked for the Chief wanted a ground rough water test inspection preformed, while I was there 3 out of 4 test failed. On top rough water test the old rubber blatters failed. In all cases mentioned I had to go back as well as the contractor to do the test over. What a pain for everyone involved and the cost to the city for reinspections. All the pipes were glued properly, it was issues like shower traps, test plugs and bladders that failed.

I'm ok with 5lbs of air or a water test, but no fernco caps allowed, I have to see the air being released and the gauges have to be in working condition. And you gotta have the puple primer or be installing approved primer and glue while I'm on the job!

pc1
 
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