Hydrotesting at Elevated Temperature ??

[pingmi]

Hello,

I need to perform a leakage test at elevated temperature 315°C and at pressure of 153.1 barg. The test needs be performed by keeping the test piece (3" Square x 2" Long) in a High temperature Chamber and pressurizing it with test fluid.
Keeping in view the safety aspects, I thought it would be good to use test medium as liquid / water instead of nitrogen gas or any other gas. At a pressure of 153.1 barg, the boiling point of water would be raised well above 315°C and that would ensure the test medium is in pure liquid state while testing.

Does any one foresee any issues to perform this test at 315°C and pressure 153.1 barg with water?
Any suggestions for Safety Measures?

Kindly revert.

Thanks.

 

[prex]

Safety issues with water will be essentially the same, if not worse, as with a gas: in case of a major leak the water flashes and is capable of delivering more energy than a gas. If your chamber is more or less tight to pressure, the issues could be really disproportionate.
You should definitely use a liquid with a boiling point higher than test temperature. As the size of your vessel is quite small, mercury is a possibility, but there should also be diathermic oils and lubricants capable of that and readily available.

prex

http://www.xcalcs.com

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[pingmi]

Thanks prex for your response. Noted your suggestion on using diathermic oils & lubricants as test fluid.
However I would like to know the suitability of water as test fluid at 315°C and 153.1 barg pressure.
Do you foresee any issues in this?

Thanks in advance.

 

[GregLamberson]

I honestly don't have any experience in testing to that high a temperature, but a few thoughts on the matter. I agree that water is the proper test medium.

My concerns would be with the small volume you have, the press change/degree change is going to be difficult to manage.

I assume once you introduce the water and bring it up to temperature, you will pressure it with heated water? Have you looked at the volume required to bring it up to test pressure at that temp? Should the test piece rupture, is the chamber built to absorb it?

Greg Lamberson, BS, MBA
Consultant - Upstream Energy
Website:

http://www.oil-gas-consulting.com

 

[pingmi]

GregLamberson,

The function of the chamber is just to control / maintain temperature during test and is not built to absorb any test piece rupture / failure.

Frankly speaking, I have not calculated the volume required to get water pressurized to 153.1 barg at 315°C temp. What would be the most reliable source to get this information? Please revert.

Thanks in advance.

 

[GregLamberson]

pingmi:

Without knowing the wall thickness of your steel cube, my rough calcs come out to only around 5.5 oz, taking into account temp. but I'm basing that on normal pipeline hydrotest calcs with temp corrections for volume. Round ups at this small volume could be significant.

As mentioned I don't have experience in hydrotesting anything at this high of temp.

But again, controlling the pressure I believe will be a challenge. I would suggest isolating the chamber and placing any personnel behind some sort of protective device.

I would guess this would need to be brought up in very small increments allowing stabilization.

I'm curious to hear from others who have been involved in high temp testing.

Greg Lamberson, BS, MBA
Consultant - Upstream Energy
Website:

http://www.oil-gas-consulting.com

 

[prex]

Well, I thought my position was expressed more clearly.
In my view water is not a suitable medium for your test. If you use gas, then, in case of a major leak or rupture, the gas will increase its volume by a factor of about 150 (the pressure ratio). With water the increase in volume is much higher in passing from liquid to steam at atmospheric pressure, so water is more dangerous than gas.
Concerning the pressurizing question, though me too I've never made this type of test, I think that, supposing you'll use a small hand pump, you only need to have the pressurizing tube coming down from your vessel, so that heat will not transmit along the tube. And of course you'll first heat up, then apply the pressure.

prex

http://www.xcalcs.com

: Online tools for structural design

http://www.megamag.it

: Magnetic brakes for fun rides

http://www.levitans.com

: Air bearing pads

 

[GregLamberson]

prex

Your position was clear, this was one of those simultaneous posts, I didn't see yours when I was posting.

Greg Lamberson, BS, MBA
Consultant - Upstream Energy
Website:

http://www.oil-gas-consulting.com

 

[JR97]

A concern I have is the sequence of pressurization and heating. If the test unit is initally heated to 315C then water is added to pressurize, the water will flash to steam upon introduction (internal test unit pressure not great enough to prevent boiling). You could try to calculate pressure growth due to thermal expansion, pressurize to calculated lower pressure with test unit at room temp, then heat. It will be extremely difficult to predict the pressure growth accurately enough based on the small test volume.

I agree with using oil or other fluid with atmospheric boiling point above 315C as test fluid. This also eliminates concern of steam flash if there is a leak / failure.