How to hydrostatic pressure test
Tips from 35 years of Hydrostatic Pressure Testing expertise
Our Micropac MP series pressure test pump offers a good quality and lightweight unit that will last for years.
This is what we have learnt over 35 years of manufacturing our Micropac pumps for pressure testing Professionals. Whether you use the pump all day, every day or only once in a while, read on.
Hydrostatic v pressure testing?
First things first. We are using the terms “hydrostatic testing”, “hydrostatic pressure testing” and “pressure testing” as the same thing. You are pressurising something to test whether it has any leakage or permanent deformation.
Our ten tips for easy pressure testing:
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Is everybody reading from the same page on what you are testing?
The first thing is to get people to agree on the pressure, fluid and “acceptance criteria.” The specification might just call for pressurising the component for test up to 1.5 times its working pressure, holding for five minutes with no leakage or permanent deformation. That is probably the simplest test specification. Look what it actually says on the customer drawing or procedure, not what you have been told it says. Have you got the latest issue of the drawing or procedure? People change things. Now sort out a plan. Look at the drawing or procedure. What pressure, fluid, how much leakage is permissible or are you just looking for no damage or permanent deformation? If the customer is referring to another document, it is no good if you have not read it and have a copy. If you have to produce a certificate as the end product of the test, what is it going to say? Clearly, if they are asking for a declaration that you simply cannot give, then this isn’t a good start. What pressure testing kit have you already got? Is it suitable?
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Check the fluid.
Oil, water or something else? Don’t pick a fluid that you cannot pump. What is more, don’t pick a fluid that contaminates the fabrication or system. You will never flush oil residue out of a water system, whatever anybody says. Whilst on fluids, be very careful of testing in anything with a low flash point. For example, a request to test on petrol or ethanol becomes a serious matter. Read our note on carrying out a Risk Assessment for Pressure testing. You must do this. The Pressure Equipment Directive has a useful graph that will help you decide whether your combination of high pressures, large volumes and hazardous fluids takes you outside “Sound Engineering Practice.” It certainly focuses the mind on what might happen if something goes wrong.
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Can you actually measure the pressure?
A pressure gauge that is not calibrated is no use. Even a calibrated pressure gauge might not be infallible. Did somebody drop the gauge yesterday and now it measures 60 bar out? I don’t know and you don’t, but at least we know that on a certain date it was checked to National Standard.
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Test safe.
Hoses and fittings need to be rated to the correct pressures. Hoses will have the working pressure on the side.Make sure the connections to the test piece are properly engineering and not a mess. They will leak or compromise safety. If the thread is an obscure UNF thread, then use it, not some BSP size that a guy at a trade counter says is probably ok. Use your Zeus tables or the web for thread details.
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Get the air out.
Bleeding from the highest point is best as you don’t want to be compressing air in a system.
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Be careful of PTFE tape.
It isn’t good stuff to have floating around as fragments of it get around a system and jam valves. Although it has its place, we rarely use it.
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Get the right pump.
Use a decent pump, preferably one of our Micropac units. We would say that, but easy and long lasting are what professionals need. Have a look at our range or talk to us if you have a particular challenge.
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Write it down.
Record the results in a log book or form with supporting serial numbers, job number, date and test technician’s name. There is no point in doing the test otherwise.
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Easy hoses and fittings to hand.
Simplify the hose and fittings so you have the minimum of searching around next time. Looking for the hose and fittings can take longer than the test. Time is money – we standardised our hoses and fittings years ago.
Thinking about this purely in business terms, it’s better to invest a little cash in your fittings now and save yourself a great deal of time and expense further down the line. We would say there is the pay back in sorting out fittings. It can’t be right to spend longer hunting for a lost fitting than doing the pressure test job.
Ideally, it’s best to buy in a range of fittings and store them in a multi-compartment box where you can see your parts at a glance. And always put the parts back in the box after use!
Big hoses? Avoid too large a hose bore as this will need filling and the fittings can be awkward. The hose will invariably prove bulky to store, expensive to buy and it won’t give high pressure ratings.
Think clean – you should store test fittings in a sealed box rather than a container that is open to the atmosphere. It is worth investing in stainless steel fittings as these won’t corrode. Plated steel fittings are cheap and disposable, but they quickly become tatty after repeated use. Throw out corroded carbon steel fittings.
As you make up fitting assemblies for connection with the free end of your hose, try to keep them assembled rather than broken down and pirated for other parts. This is depressing!
Quick disconnects can help you to switch quickly between test fittings but take care to avoid damage to seals and leakage. I think that this risk of leakage from them is our one niggle over many years. More generally, the more connections you have in a test hose assembly, the higher the risk of an annoying leak – always buy in a one-piece fitting if possible! On stainless steel fittings, we would look at Pegasus, Nero or Hydrasun in Aberdeen who keep formidable stocks of obscure fittings for the offshore industry.
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Look for external leaks before panicking.
Look for external leaks on pipe work and hoses before worrying that the job is leaking. When you certify that something shows no permanent deformation, do quietly look at the job. Things can deform dreadfully and can easily be missed.
You may also be interested in;
Our ten tips to make a hydrostatic pressure test easy. What we have learnt over 35 years.
Sample of Risk Assessment for Pressure Testing. Essential if you are working under pressure.
How to Hydrostatic Test including a sample procedure.
Our YouTube video “how to burst test” shows a Micropac pump used for a simple but safe burst test.
Links
Pegasus Hydraulics for stainless steel fittings
Nero for stainless steel fittings
Hydrasun for massive stocks of tricky stainless steel fittings
Parker Hannifin hoses and fittings for a comprehensive range.
Micropac pressure test pumps are on the Sarum Hydraulics site.
Want to buy a Micropac pressure test set for use on site next day? Try Pump Shop Pro, our in-house Distributor.
So why choose a Micropac pump?
All the supports on which tested equipment is exposed to the hydrotest shall have enough strength.
Don’t forget to wear appropriate PPE to protect you from potential hazards.
Thank you Hauzan. You are right. Making the testing safe is the first priority and your suggestion on wearing PPE and supporting all the equipment properly is vital. John
Thank you for sharing this valuable information with us. It was worth reading. It had all the information that was required looking forward to read more of these articles.
Very useful information is shared by you. While doing leak testing self protection is utmost . Keep sharing these types of good information so that general people can aware from it.
Thank you for reading our blog, Daniel Gurgov. Yes, you are right. You need to protect people from hazard during pressure testing.
This article is full of some well-researched information. You have made valid points in a unique way. This article helps me gain an understanding of the Hydrostatic Pressure Test