Liquid Thermal Expansion causing leaks 3

[slickstyles5]

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

 

[BigInch]

A BB valve isn't required for pressure relief. He's asking how to vent across one if its there for other purposes, such as preventing product contamination. Supposedly you could vent to the DBB or SBB cavity and out to a drain as long as the vented fluid could not find its way across to the other fluid. I'm just saying I'd rather not deal with that and vent across it to someplace eventually going to a relief header, rather than chance contaminating products.

Let your acquaintances be many, but your advisors one in a thousand’ ... Book of Ecclesiasticus

 

[willhammett]

I didn't not mean to start a debacle, sorry for bringing up a moot point, the fact that not all fluids are compressible in certain situations does not pertain to this topic and I should not have brought it up. Thanks for the links ione and biginch.

 

[BigInch]

Will, as it happens it is one of my biggest triggerpoints. That said, it's more important to realize that if you have the problem, one needs to know that relief valves are probably going to be required by the design code. For fluids, you must calculate the pressure of the fluid's volume (volume of the pipe at fabrication temperature) when expanded to max temperature and then restrained to the volume of the pipe at that temperature. For partially filled pipe segments you should be conservative and assume that they are completely full of liquid. If you know they can never be completely full of fluid, you must determine the vapor pressure of the fluid at the max temperature you expect to reach.

Let your acquaintances be many, but your advisors one in a thousand’ ... Book of Ecclesiasticus

 

[slickstyles5]

Biginch, I didn't want to use a Block & Bleed valve as I didn't see how it would solve the problem of thermal expansion in a closed circuit. Do you see how it can be useful? The only option I really see if a properly sized accumulator with a pre-charge just above max operating pressure.

I need to start working on the schematics to really study the situation.

 

[hydtools]

galeblanc, also consider a spring-loaded accumulator, if available, then you don't have to routinely check precharge.

Ted

 

[BigInch]

Is your pipe a pipeline going from city A to city B, or is it a fuel line in some airplane or rocket ship. We do not like rocket science and keep things simple in pipeline work, so we do not use accumulators. We us pressure relief valves and relieve to a drain to an oily-water hydrocarbon sump tank.

Let your acquaintances be many, but your advisors one in a thousand’ ... Book of Ecclesiasticus