Liquid Thermal Expansion causing leaks
Liquid Thermal Expansion causing leaks
(OP)
Hello,
I have a pipeline of fuel which is currently leaking and I am suspecting that it is due to thermal expansion. I have a section that is closed between two ball valves and then then the ambient temperature increases and the pressure increases to the points where leaks are caused.
I'm assuming the easiest solution is a hydraulic accumulator. Are there any other alternatives?
ps. I need to keep the liquid in the line, so a pressure relief valve is not an option.
Thanks
Gabriel
I have a pipeline of fuel which is currently leaking and I am suspecting that it is due to thermal expansion. I have a section that is closed between two ball valves and then then the ambient temperature increases and the pressure increases to the points where leaks are caused.
I'm assuming the easiest solution is a hydraulic accumulator. Are there any other alternatives?
ps. I need to keep the liquid in the line, so a pressure relief valve is not an option.
Thanks
Gabriel





RE: Liquid Thermal Expansion causing leaks
Whats the process conditions, fluid etc.... this could be one of many different things.
RE: Liquid Thermal Expansion causing leaks
RE: Liquid Thermal Expansion causing leaks
RE: Liquid Thermal Expansion causing leaks
RE: Liquid Thermal Expansion causing leaks
passive but at least an alternative. Also assuming the fluid past
the second ball valve is discharged.
What about a third ball valve? Close the loop as usual then close a
third ball valve beyond the second then reopen the second ball
valve. Lower initial pressure lessens thermal effects.
RE: Liquid Thermal Expansion causing leaks
Regards,
SNORGY.
RE: Liquid Thermal Expansion causing leaks
Now you can:
1) Prevent thermal expansion keeping the fuel temperature increase as low as possible
2) Consider an expansion tank that would accommodate the expanded volume
RE: Liquid Thermal Expansion causing leaks
Jmore1, thermal expansion of both the jet fuel and the pipe will result in a pressure increase, because the expansion modulus of the jet fuel is greater than the pipe's increase in volume for the same temperature difference and the jet fuel's bulk modulus is high, resulting in great pressure increases with only a very small amount of compression of the jet fuel.
galeblanc, all fluids are compressible. In fact everything is compressible. Ask a rock that is 20,000 feet below the Earth's surface, a piece of steel in a bridge pier, or what was 1 cubic foot of seawater at 0 MSL when it finally gets down to a depth of 5000 ft.
What is needed here is in fact a code required device known as a thermal relief valve that is needed whenever fluid in a closed off space (trapped between two valves, etc.) can become heated, when due to ambient temperatures, or emergency conditions, such as fire, arise.
Let your acquaintances be many, but your advisors one in a thousand' ... Book of Ecclesiasticus
RE: Liquid Thermal Expansion causing leaks
RE: Liquid Thermal Expansion causing leaks
But OK, I'll bite. Which fluid do you think would be an example of your noncompressible theory? Be sure you know the value of its bulk modulus property before answering.
Is the bottom of the ocean open or closed? Open or closed doesn't matter, only thing that matters is if there is pressure or not and how many significant figures is important to you.
If water didn't compress, sound would not travel through it, but we all know that water manages to carry sound 6 times faster than air. How far away can you hear the engine coming when you put your ear on a steel railroad track.
Let your acquaintances be many, but your advisors one in a thousand' ... Book of Ecclesiasticus
RE: Liquid Thermal Expansion causing leaks
I agree there are cases where liquids can be considered not compressible, and this implies a certain degree of discretion, which is related to "engineering sensibility".
Anyway I think this is not the case. I think it's worth the effort to take a glance at the FAQ below
http://www.eng-tips.com/faqs.cfm?fid=1339
RE: Liquid Thermal Expansion causing leaks
So either a thermal reilef valve discharging to a storage tank or use of a compressible bladder may be the way to go.
RE: Liquid Thermal Expansion causing leaks
Ted
RE: Liquid Thermal Expansion causing leaks
biginch, a thermal relief valve is installed in series or you have to install a tee and then link it back to the tank? doesn't it act as a pressure relief valve? do you know of any manufacturers? i am looking at a pipe size of 1-1/2 in. with jet fuel in the lines.
ps. i did some calculations and it's pretty crazy that the pressure rises significantally with an increase in temp. just 2 deg F, will cause an increase of pressure of 180 psi, and 20 deg F will cause an increase of 3600 psi. i didn't think it was that big of a pressure increase. it's no wonder that everything leaks.
RE: Liquid Thermal Expansion causing leaks
Fluid Expansion Effects.
A vertical piece of capped pipe, or any capped pipe, is capped or otherwise closed off, ie. isolated by being trapped between two closed valves, etc. and thereby also presumedly subject to fluid expansion and subsequent increased pressure and even if the capped portion of pipe was filled with vapor (saturated vapor in equilibrium with the fluid below) and the fluid expanded into the vapor space thereby only compressing the vapor, then the pressure would still reach that of the saturation pressure at whatever temp the system had at any given moment, which, if higher than the design pressure, must be relieved in accordance with the above clause.
Let your acquaintances be many, but your advisors one in a thousand' ... Book of Ecclesiasticus
RE: Liquid Thermal Expansion causing leaks
Let your acquaintances be many, but your advisors one in a thousand' ... Book of Ecclesiasticus
RE: Liquid Thermal Expansion causing leaks
What about a double block and bleed valve? Would it be useful in our case?
RE: Liquid Thermal Expansion causing leaks
Let your acquaintances be many, but your advisors one in a thousand' ... Book of Ecclesiasticus
RE: Liquid Thermal Expansion causing leaks
RE: Liquid Thermal Expansion causing leaks
Let your acquaintances be many, but your advisors one in a thousand' ... Book of Ecclesiasticus
RE: Liquid Thermal Expansion causing leaks
RE: Liquid Thermal Expansion causing leaks
Let your acquaintances be many, but your advisors one in a thousand' ... Book of Ecclesiasticus
RE: Liquid Thermal Expansion causing leaks
I need to start working on the schematics to really study the situation.
RE: Liquid Thermal Expansion causing leaks
Ted
RE: Liquid Thermal Expansion causing leaks
Let your acquaintances be many, but your advisors one in a thousand' ... Book of Ecclesiasticus