Pressure testing water pipes

[Fruit Trader]

Leak testing with air. Apply pressure to a pipe system and monitor the pressure over time. The applied pressure can be from a few millibars to several bar depending on the application.

[grollies]

1 hour ago, 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.

 

I think in this case to try to dismiss evidenced-based vidoe as being from a couple of YouTube warriors is a mistake. Sure, there is much on YouTube not to like. But the two examples submitted are worthy of consideration in this instance and I repeat my advice to those here considering pneumatic testing of pipework and pressure tanks as to be extremely bad practice. You obviously are unwilling to accept advice from me. (Not wishing to appear big-headed) I wrote the training course in the UK for Gas Inspection Engineers witnessing pressure tests, without such ticket they cannot sign-off a pressure test, so my experience is valid.

 

Your later comment re: pneumatic testing at millibars or a 'couple of bar' pressure holds no water. The OP is testing with air at 7 barG and this is not advisable. The video above demonstrates a low volume compressor failing at 7 bar. Imagine if this was a 2m3 pressure tank that some unfortunate here decided to take your advice and tested with air. And it failed......

 

The worst practice when pneumatic testing is to approach the pipework/system and inspect for leaks at test pressure.

 

Your YouTube comment is commensurate with a total lack of understanding of the principles of pneumatic v hydrostatic testing and of the dangers involved and I strongly advise those considering pneumatic testing of water systems not to do so.

 

Pneumatic testing is only undertaken when introducing water into a pipe system would damage the system i.e. LNG cryogenic pipework, or the above example of pressure testing of aircraft fuel tanks.

[Artisi]

Simple safety advice is "DON'T TEST WITH AIR" 

[tutsiwarrior]

for most home plumbing systems an in service leak test should be all that's required except of course where you have joints that may not be accessible when the installation is finished...a lot of construction QC inspection and test plans for commercial purposes will require a 1.5 working pressure hydro test for additional assurance...

 

that little hand held hydro test pump that someone posted earlier looks really neat...I'd like to have one of those...havta fit yer own gauge looks like...

 

 

[Fruit Trader]

17 minutes ago, grollies said:

Your later comment re: pneumatic testing at millibars or a 'couple of bar' pressure holds no water. The OP is testing with air at 7 barG and this is not advisable. The video above demonstrates a low volume compressor failing at 7 bar. Imagine if this was a 2m3 pressure tank that some unfortunate here decided to take your advice and tested with air. And it failed......

It holds no water because its using air. I really don't care about the OP's 100 PSI as it does not enter my argument. You can safely leak test PVC pipe with air and that's a fact. No amount of tube videos, regulations or personal experience is going to change that. 

 

The cheap shots about my knowledge I don't care about, but please stop making up stories about my posts unless you have the evidence to back them up.

[grollies]

2 minutes ago, Fruit Trader said:

You can safely leak test PVC pipe with air and that's a fact

No you can't and no, it isn't. You don't understand the principles involved. I'm done trying to reason with you.

[Ron jeremy]

Absolutely nothing wrong with this drop in pressure, a few pounds over a 24 hour period can be due to temperature fluctuations, etc.

there is a rather small amount of piping in a home, a leak would most likely be heard at 100 psi. And the test would drop a lot more than a few pounds. Water test would be better, nothing wrong with an air test. 

for piece of mind, mix some dish soap with water and soap the joints. Look for bubbles.

youre quite ok . 

I am a plumber by the way.

problem with a water test is air becomes trapped in high points, and pressures really fluctuate if the air can't be takin out of the system.

we pressure test systems ALL the time with air, 

enjoy your new home.

[tutsiwarrior]

it's true that fuel supply pipes for power generation are many times leak tested with nitrogen when the pipe hasta remain in a dry condition afterwards and are preserved that way prior to start up and when there's a shut down of any duration...

[sometimewoodworker]

1 hour ago, Ron jeremy said:

nothing wrong with an air test. 

Did you miss the fact that you are testing PVC pipe and that the failure mode is to explosively shatter and that if you are in the wrong place at the wrong time the shattered pipe is quite capable of killing you.

 

SO NO LEAK TESTING OF DOMESTIC PVC PIPE WITH AIR IS NEVER SAFE. Leak testing requires the system to be pressurised.

[sometimewoodworker]

1 hour ago, tutsiwarrior said:

it's true that fuel supply pipes for power generation are many times leak tested with nitrogen when the pipe hasta remain in a dry condition afterwards and are preserved that way prior to start up and when there's a shut down of any duration...

Are they PVC?

 

Pneumatic testing of other materials may be acceptable as the failure mode is different.

[sometimewoodworker]

3 hours ago, Fruit Trader said:

We are leak testing not pressure testing.

Leak testing requires the system to be pressurised.

 

Unless there is some magical kind of physics that is secret to the PVC leak testing group. ????

[emptypockets]

,Without getting into the pros and cons , it is very simple to just pressurise a domestic system with whatever medium it will be transporting. In this case just hook the water pump up to the system and let it pressurise - you'll soon see the leaks if there are any.

One of the biggest challenges I have had in my working career is to make people understand the nature of compressed air. At different times I have had electricians do cross trade training into the instrument and control field. They certainly understand the dangers of electricity but trying to explain to them about compressed air was very difficult in some cases.

I've seen the aftermath of a poorly assembled control valve rotatory actuator where the pinion has taken off and punched a hole through the ceiling. Fortunately the guy didn't have any damage apart from a code brown event in his underpants. He could have easily been killed. Only talking about 80psi or so here. Do the maths - 80 pounds per square inch. Assume the pressurised device is 100 square inches - 8000 pounds of force or around 2 tons. Quite a lot of stored energy here. When it's released explosively it can be life changing. Or life ending. Ask any tyre fitter about split rims and they will all have a story to tell.

In my opinion compressed air is much more dangerous than electricity and I've worked with both for over 45 years as a tradesman, supervisor, engineer and manager.

Edited August 14, 2019 by emptypockets

[elliss]

5 hours ago, 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.

 

 Water hammer , i just love that term .

     Would that have been caused by air in the system ?. 

 

[emptypockets]

20 minutes ago, elliss said:

 

 Water hammer , i just love that term .

     Would that have been caused by air in the system ?. 

 

Or a vacuum due to cavitation. Can be disastrous. I've seen quite a few pipes rupture due to cavitation. Particularly steam condensate pipes.

[tutsiwarrior]

5 hours ago, sometimewoodworker said:

Are they PVC?

 

Pneumatic testing of other materials may be acceptable as the failure mode is different.

nah, usually CS transitioning to SS at the downstream burner vendor's scope of supply...I believe for the purposes of our discussion the applicable code should have the last word regarding a leak testing procedure that would necessarily address the material stress limitations...that's what they're there for...

 

 

[tutsiwarrior]

4 hours ago, elliss said:

 

 Water hammer , i just love that term .

     Would that have been caused by air in the system ?. 

 

 

nah, water hammer results from a change in momentum of the fluid in the pipe usually caused by a valve closing or a pump shutting down unexpectedly, nothing to do with air...mass constant but a change in velocity...

 

'I'se gwine take my water hammer an' I'se gwine t'whup ye...'

 

 

[sotonowl]

My comments,

1) Gauge looks a bit manky but as long as it zeros when the pressure is released it is probably OK.

2) Pressure drops in systems where temperature drops, was there any noticeable change in temperature during the test.

3) Joints can be checked using soapy water when testing with air, just mix some fairy liquid with water and spray the joints, soon bubbles up if it's leaking.   

4) As others have said, testing with gases can be dangerous, but considering the volumes involved (I take it you were just testing small bore pipes) and the pressure you've gone to I'd be happy to test to that if I was controlling the test.

Why didn't he just test with water? Easy enough with a bucket pump.

[superal]

9 hours ago, emptypockets said:

,Without getting into the pros and cons , it is very simple to just pressurise a domestic system with whatever medium it will be transporting. In this case just hook the water pump up to the system and let it pressurise - you'll soon see the leaks if there are any.

One of the biggest challenges I have had in my working career is to make people understand the nature of compressed air. At different times I have had electricians do cross trade training into the instrument and control field. They certainly understand the dangers of electricity but trying to explain to them about compressed air was very difficult in some cases.

I've seen the aftermath of a poorly assembled control valve rotatory actuator where the pinion has taken off and punched a hole through the ceiling. Fortunately the guy didn't have any damage apart from a code brown event in his underpants. He could have easily been killed. Only talking about 80psi or so here. Do the maths - 80 pounds per square inch. Assume the pressurised device is 100 square inches - 8000 pounds of force or around 2 tons. Quite a lot of stored energy here. When it's released explosively it can be life changing. Or life ending. Ask any tyre fitter about split rims and they will all have a story to tell.

In my opinion compressed air is much more dangerous than electricity and I've worked with both for over 45 years as a tradesman, supervisor, engineer and manager.

Digressing slightly . There have been many casualties / deaths suffered by tyre fitters , especially when working on commercial vehicles . H&S UK regs demand that the tyres are inflated and tested within a steel cage . Have you ever heard a trucks tyre explode ? tis same as a bomb blast  

[bankruatsteve]

The FACT is that air can be compressed much more than a liquid.  For that reason, there is more potential for a hazardous event with compressed air.  I don't see the sense in testing a PVC water system with air because other than proving no leak, it would be useless for finding a leak (and soap bubbles only help if the fault can be seen).  

[superal]

My experience with the blue plastic water pipe here in Thailand is that it does not always perform as it should . In a 2 year period I had 2 fittings fail by splitting , one was a 2 inch to 1 inch reducer and the other was a 1 inch 90 degree slow bend , both bought at Global . working under normal domestic pumped water from the well .    Had other leak problems , which were impossible to trace as they were within the structure of the house , which made the water pump activate every 20 seconds cos of loss of pressure . Remedy was to rerun the entire pipe work to surface so as easy to inspect and maintain plus I get a free hot shower every evening cos of the exposed piping . 

Air testing is a last resort especially against a glued joint .   To the poster Bassosa , bite the bullet pal and take the well meant good experienced advice from your friends on this forum and that applies to all of us 

[maxpower]

Most of our wet pipework on new installations goes through a dry testing procedure before commissioning including ABS and PVC I have no idea what pressures are applied or what procedures are used when performing these leak tests. Work areas are not evacuated during the test which leads me to believe the pipework company must be using a procedure that satisfies our strict safety rules. A work colleague informs me that some kind of bottled gas is used during the test procedures. The videos posted earlier show how pipes made from brittle materials can shatter under pressure which leads me to believe the tests on our systems are made using pressures that present little or no risk to people working in the test area. I have witnessed the insurance company making low pressure leak tests on our LPG lines so maybe the tests on our plastic water lines are made using similar low pressure procedures. Safety rules for test procedures are often written from risk assessment based on human error but this does no mean the procedures cannot be safely carried out by properly trained personnel.

[emptypockets]

13 hours ago, emptypockets said:

,Without getting into the pros and cons , it is very simple to just pressurise a domestic system with whatever medium it will be transporting. In this case just hook the water pump up to the system and let it pressurise - you'll soon see the leaks if there are any.

One of the biggest challenges I have had in my working career is to make people understand the nature of compressed air. At different times I have had electricians do cross trade training into the instrument and control field. They certainly understand the dangers of electricity but trying to explain to them about compressed air was very difficult in some cases.

I've seen the aftermath of a poorly assembled control valve rotatory actuator where the pinion has taken off and punched a hole through the ceiling. Fortunately the guy didn't have any damage apart from a code brown event in his underpants. He could have easily been killed. Only talking about 80psi or so here. Do the maths - 80 pounds per square inch. Assume the pressurised device is 100 square inches - 8000 pounds of force or around 2 tons. Quite a lot of stored energy here. When it's released explosively it can be life changing. Or life ending. Ask any tyre fitter about split rims and they will all have a story to tell.

In my opinion compressed air is much more dangerous than electricity and I've worked with both for over 45 years as a tradesman, supervisor, engineer and manager.

Should have said 4 tons not 2.

[JAS21]

He tested at 100psi ...he must be a 'kin idiot. Always test with water and ensure that all the system is fully vented before commencing the test. It is not necessary to test much above the NWP half as much again would be more that adequate.... on house pipework...but checking for none glued joints (no glue) it might be an idea to give the system a little bit of water hammer and then test again .... we had one and it didn't show up for quite a few weeks... somehow the guy managed to get a few floor tiles up without breaking them ...

 

 

Edited August 15, 2019 by JAS21