Pressure testing water pipes

[Bassosa]

Hello everyone,

 

Our builder is (air) pressure testing our water pipes for leaks. We don't have a gravity fed system, but rely on a pump constantly pressurising the water system, so I guess it's even more important to not have leaks.

 

Over 24 hours we did see a drop in pressure but it's been stable ever since.

 

Does this warrant further inspection or is this drop in pressure within tolerances?

 

Thanks for your comments.

 

 

[griffon2011]

I would be suspect of that pressure gage.  It is supposed to be a precision instrument but it looks like it has been used as a hammer. If possible leave it pressurized for a couple of days.  My tolerance would be no leaks.  

You might want to get some of the liquid that kids use to make bubbles and apply to each joint and look for bubbles.  Small leaks can be surprisingly hard to find without proper equipment but the damage (mold etc) from leaks over a long period of time can add up.  

[VocalNeal]

What pressure does the pump deliver? 3 bar? 4 bar? So if it is holding 7. Blue pipe is rated at 13.5 I believe.

 

Pump up again to the original pressure and wait again to see if it drops again. 

 

As for the gauge some times repeatability is more important than accuracy. That the installer has one at all is a good sign.

[sometimewoodworker]

  On 8/14/2019 at 7:23 AM, VocalNeal said:

What pressure does the pump deliver? 3 bar? 4 bar? So if it is holding 7. Blue pipe is rated at 13.5 I believe.

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The pressure that blue pipe is designed for very much depends on which grade of pipe you buy.

 

most people use grade 5 and the rating is 5 kgf/cm² so slightly under 5 bar at 4.9 bar

  Quote

Working pressures of PVC pipes class PVC 5, PVC 8.5 and PVC 13.5 are 5, 8.5 and 13.5 kgf/cm² at 27ºC respectively.

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[griffon2011]

  On 8/14/2019 at 7:23 AM, VocalNeal said:

What pressure does the pump deliver? 3 bar? 4 bar? So if it is holding 7. Blue pipe is rated at 13.5 I believe.

 

Pump up again to the original pressure and wait again to see if it drops again. 

 

As for the gauge some times repeatability is more important than accuracy. That the installer has one at all is a good sign.

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I agree that it is a good sign that the installer uses a gauge but if it is not accurate it has no value.  Look at all the corrosion and dents on the gauge, it clearly has been abused.  How would you know if the needle sticks at some point and does not indicate a loss of pressure or conversely you could possibly over pressurize the system and damage it.  

[Bassosa]

As usual, very useful comments. Many thanks.

 

Am I right in assuming that if there's indeed a leak the air pressure would over time drop to 0?

 

Obviously only if you don't keep pressurising the system, ie "keep the pump on"?

[superal]

  On 8/14/2019 at 8:38 AM, griffon2011 said:

I agree that it is a good sign that the installer uses a gauge but if it is not accurate it has no value.  Look at all the corrosion and dents on the gauge, it clearly has been abused.  How would you know if the needle sticks at some point and does not indicate a loss of pressure or conversely you could possibly over pressurize the system and damage it.  

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Pneumatic testing can be dangerous and the preferred test is hydro which will also detect leaks better than air . Air testing on plastic piping to me is a no goer . 

The gauge shown has probably never been calibrated and looks like it should be scrapped . Dont take my word for it , just Google it and see the dangers with air testing .

[bankruatsteve]

Are the pipes hooked up to anything or just capped?  Anyway... if it holds stable at 100psi you should be good.  The gauge doesn't need to be accurate for this kind of test and any leak would definitely show a drop in pressure.  If there is a faucet hooked up, open a smidgen and you should see the pressure drop.

[Artisi]

  On 8/14/2019 at 9:10 AM, bankruatsteve said:

Are the pipes hooked up to anything or just capped?  Anyway... if it holds stable at 100psi you should be good.  The gauge doesn't need to be accurate for this kind of test and any leak would definitely show a drop in pressure.  If there is a faucet hooked up, open a smidgen and you should see the pressure drop.

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With air-  a slight leak is hard to pick, far better to test with water, however you're not - so as bankruatsteve has said, hold the pressure as you have done, but bleed off a little air  - mainly to check if the guage see's an change of pressure. 

[Fruit Trader]

First you need to be sure the beat up pressure gauge is not sticking. It should stay at the same reading when lightly tapped and immediately indicate any drop in pressure.

 

At 100 PSI over 24 hours there should be no pressure drop on a properly capped off system. If male or female outlets have been thread capped, its more difficult to locate leaks indicated by a pressure drop.

[grollies]

Oh, God.......

 

I owned one of the only two specialist cross-country gas and water pipeline pressure testing companies in the UK up until 2015.

 

DON'T do that again with air. Please.

 

The drop in pressure is due to the elastic creep of the PVC pipe.

 

If the pressure has dropped slightly (I know, the pressure gauge is shiiite) then held for a minimum 1 hour, drop the pressure, the test is ok.

 

DO NOT pump up the pressure again as you will continue to expand the plastic pipe, possibly to the point of failure. People get killed with relatively small volumes of pneumatic pressure being inadvertantly released.

 

Comparison:

Pop a ballon filled with water

Pop a ballon filled with air............

 

Next time, do it with water.

[Fruit Trader]

  On 8/14/2019 at 10:06 AM, grollies said:

DON'T do that again with air. Please.

 

The drop in pressure is due to the elastic creep of the PVC pipe.

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If you are within the pipes working pressure there will be no problem or any significant distortion of the pipe. 

[Artisi]

  On 8/14/2019 at 10:06 AM, grollies said:

Oh, God.......

 

I owned one of the only two specialist cross-country gas and water pipeline pressure testing companies in the UK up until 2015.

 

DON'T do that again with air. Please.

 

The drop in pressure is due to the elastic creep of the PVC pipe.

 

If the pressure has dropped slightly (I know, the pressure gauge is shiiite) then held for a minimum 1 hour, drop the pressure, the test is ok.

 

DO NOT pump up the pressure again as you will continue to expand the plastic pipe, possibly to the point of failure. People get killed with relatively small volumes of pneumatic pressure being inadvertantly released.

 

Comparison:

Pop a ballon filled with water

Pop a ballon filled with air............

 

Next time, do it with water.

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You need to talk to the "plumber" not the end user, unfortunately not the first time it's been done and won't be the last. 

You should add, pop a balloon filled with water under pressure (air free of course) 

But don't fret, it will be done over and over - as farangs don't understand Thai air. 

[griffon2011]

  On 8/14/2019 at 9:04 AM, superal said:

Pneumatic testing can be dangerous and the preferred test is hydro which will also detect leaks better than air . Air testing on plastic piping to me is a no goer . 

The gauge shown has probably never been calibrated and looks like it should be scrapped . Dont take my word for it , just Google it and see the dangers with air testing .

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Yes I agree with that.  I became very aware of the dangers when one of my inspectors blew up the wing tank on a corporate jet a few years ago.  The pressures to perform the leak test were less than 2 psi but I'm not sure how much pressure was applied before the tank (wing) failed.  

[grollies]

  On 8/14/2019 at 10:13 AM, Fruit Trader said:

If you are within the pipes working pressure there will be no problem or any significant distortion of the pipe. 

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Says a man who doesn't understand or appreciate pneumatic testing. I can elaborate further if you like.

 

I've known of many personnel killed in pneumatic testing accidents.

 

National Grid only allows pneumatic pressure testing of HDPE gas distribution pipelines AFTER an initial hydrotest to check structural integrity. The hydrotest is done at 1.5 x WP, the pneumatic test at 1.1 x WP. There's a reason for this.

 

I personally experienced hydrotest failure twice. If those failures had occured under pneumatic test failure deaths would have occured.

 

Pressure test with water. End of. Period.

[grollies]

  On 8/14/2019 at 10:36 AM, griffon2011 said:

Yes I agree with that.  I became very aware of the dangers when one of my inspectors blew up the wing tank on a corporate jet a few years ago.  The pressures to perform the leak test were less than 2 psi but I'm not sure how much pressure was applied before the tank (wing) failed.  

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And I bet it went with a bit of a bang.

[Fruit Trader]

  On 8/14/2019 at 10:37 AM, grollies said:

Says a man who doesn't understand or appreciate pneumatic testing. I can elaborate further if you like.

 

I've known of many personnel killed in pneumatic testing accidents.

 

National Grid only allows pneumatic pressure testing of HDPE gas distribution pipelines AFTER an initial hydrotest to check structural integrity. The hydrotest is done at 1.5 x WP, the pneumatic test at 1.1 x WP. There's a reason for this.

 

I personally experienced hydrotest failure twice. If those failures had occured under pneumatic test failure deaths would have occured.

 

Pressure test with water. End of. Period.

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We are talking about a PVC home plumbing system which can be safely tested with air and often are. No need to bring in some National Grid regulations and apply them globally. 

Some of the worst accidents on PVC pipelines are caused by water hammer but that's another story.

 

Plumbers often have dramatic fits about pressure testing with air but continue to charge new systems to full supply pressure creating pockets of air and stored energy throughout a system.

[Artisi]

  On 8/14/2019 at 10:59 AM, Fruit Trader said:

We are talking about a PVC home plumbing system which can be safely tested with air and often are. No need to bring in some National Grid regulations and apply them globally. 

Some of the worst accidents on PVC pipelines are caused by water hammer but that's another story.

 

Plumbers often have dramatic fits about pressure testing with air but continue to charge new systems to full supply pressure creating pockets of air and stored energy throughout a system.

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Well, if it does fail under air pressure it will be dramatic. 

[Fruit Trader]

  On 8/14/2019 at 11:08 AM, Artisi said:

Well, if it does fail under air pressure it will be dramatic. 

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The real dramas occur when plumbers attempt to pressure test drainage pipes using air. 

[grollies]

  On 8/14/2019 at 10:59 AM, Fruit Trader said:

We are talking about a PVC home plumbing system which can be safely tested with air and often are. No need to bring in some National Grid regulations and apply them globally. 

Some of the worst accidents on PVC pipelines are caused by water hammer but that's another story.

 

Plumbers often have dramatic fits about pressure testing with air but continue to charge new systems to full supply pressure creating pockets of air and stored energy throughout a system.

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OK, look, the National Grid example was just that, an example of why a hydrotest at 1.5 barG is applied before a final pneumatic test at 1.1 x WP.

 

As much as I respect your posts in general you are straying into dangerous territory here.

 

I understand many of you guys have 'pressure tank' water supply systems. IF you are installing from new and testing up to 7 barG (100psiG) the outcome could be catastrophic. It's all well and good saying the pipe is rated at 10 bar but there's no accounting for Somchai's installation competance.

 

The following video is one we used in my company to demonstrate how a small volume of compressed air at 7 barG (100 psiG) has devastating effects.

 

This guy was lucky his Grandson was around to apply tourinquets to his arms and legs and call 911. Grandad spent over a month in hospital.......all from a small air compressor failing at pressure.

 

Like I said, I have 25 years in the pipeline pressure testing industry but if you can't respect my opinion then there's not much more I can add.

 

 

[sometimewoodworker]

  On 8/14/2019 at 10:59 AM, Fruit Trader said:

We are talking about a PVC home plumbing system which can be safely tested with air

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Completely wrong and potentially extremely dangerous and deadly. Here is an air pressure fail. In progress 

 

 

[Fruit Trader]

So if there is no pressurised water available we skip a leak test ?

I guess like Wiki, YouTube is the end game for some.

 

[Fruit Trader]

  On 8/14/2019 at 11:35 AM, sometimewoodworker said:

Completely wrong and potentially extremely dangerous. Here is an air pressure fail. In progress 

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No not completely wrong. Expand your research beyond the Tube

[grollies]

  On 8/14/2019 at 11:41 AM, Fruit Trader said:

So if there is no pressurised water available we skip a leak test ?

I guess like Wiki, YouTube is the end game for some.

 

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Like I said, you don't know what you are talking about. And, with respect, I've seen photos of your farm with HP triple-ram pumps capable of 40 barG water pressure.

[Fruit Trader]

  On 8/14/2019 at 11:45 AM, grollies said:

Like I said, you don't know what you are talking about. And, with respect, I've seen photos of your farm with HP triple-ram pumps capable of 40 barG water pressure.

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I think you have lost the plot. The only ram pump I have is on the pressure washer.

[sometimewoodworker]

  On 8/14/2019 at 11:41 AM, Fruit Trader said:

So if there is no pressurised water available we skip a leak test ?

I guess like Wiki, YouTube is the end game for some.

 

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You did not watch to see that all plumbing codes, manufactures and safety bodies specifically prohibit testing with air

 

a water pressure test kit is small hand pumped and not expensive.

[sometimewoodworker]

  On 8/14/2019 at 11:45 AM, Fruit Trader said:

No not completely wrong. Expand your research beyond the Tube

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Please provide any reputable standard that supports your conclusion. Don't forget you are claiming that domestic PVC PIPE can safely be air pressure tested and that is what I address.

[Fruit Trader]

  On 8/14/2019 at 11:53 AM, sometimewoodworker said:

Please provide any reputable standard that supports your conclusion. Don't forget you are claiming that domestic PVC PIPE can safely be air pressure tested and that is what address.

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We are leak testing not pressure testing. If you go back through my posts you will find no mention of pressure when I say PVC pipes can be safely tested using air. The OP shows 100 PSI which is his story not mine.

[grollies]

  On 8/14/2019 at 11:48 AM, Fruit Trader said:

I think you have lost the plot. The only ram pump I have is on the pressure washer.

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Yep, that's the one, it was on a photo you posted one time about pressure fittings. And if you are advocating pneumatic testing PVC pipe it's you who has lost the plot my friend.

[Fruit Trader]

  On 8/14/2019 at 12:22 PM, grollies said:

Yep, that's the one, it was on a photo you posted one time about pressure fittings. And if you are advocating pneumatic testing PVC pipe it's you who has lost the plot my friend.

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I will leave you to work out the plot.