Natural gas pipe temperature

[lola.furtado]

Hi guys! I'm a student working on a class proyect and i have two questions:

I have to design a gas pipe. ¿Should i use a maximum temperature or a minum one? ¿Why?

Sorry if it's the wrong forum!
Please help me, thank you!!

 

[akpipelineengr]

What kind of gas? What kind of pipe? Do you have a design code? How long is the pipe?

Design temperature is important, but we're going to need a lot more detail from you.

 

[rb1957]

you'll probably need to consider both ... why ? (we can tell you, but you'll learn better if you discover it for yourself).

 

[lola.furtado]

you'll probably need to consider both ... why ? (we can tell you, but you'll learn better if you discover it for yourself).

Hi, thanks for answering! Sorry i didn't explain it well.

I'm studying about central tank batteries, and i need to calculate the diameter of a natural gas pipe that comes out of a separator. I know how to do that, but i'm not very sure about the temperature.

I'm working with:

• 9 kg/cm2 pressure
• ambient temperature

At first i was between three options: the highest, the lowest or the average one. Later i thought that i should assume operation under the worst cases situations, and that's why i didn't consider the average temp.

So wich one should i use?

Thanks again!

 

[lola.furtado]

What kind of gas? What kind of pipe? Do you have a design code? How long is the pipe?

Design temperature is important, but we're going to need a lot more detail from you.

Hi! Thanks for answering!

I only need to know the diameter of the pipe. It's a natural gas pipe coming out of a separator (in a central tank battery).

I'm working at ambient temperature. My question is which temperature should i consider, the highest or the lowest? I ruled out the average temp because i thought i should assume operation under the worst scenarios.

Thanks again!

 

[Snickster]

You will need to consider both for different design reasons. If you are looking at piping stress then you will need to consider the maximum and minimum temperatures of operation of a piping system to determine the thermal expansion stress range. If you are looking at the maximum velocity in the pipe of 60 ft/sec based on noise then the velocity is maximum at the highest temperature, and pressure drop is maximum also at highest velocity. If you are looking at heat transfer and loss of heat in the pipe then the pipe will lose most heat when temperature of fluid versus ambient temperature has maximum differential. Depends on what facet of the design you are looking at.

 

[pierreick]

Hi,
If you need to perform calculation:

CheCalc ‐ Fluid Flow

Calculation for pressure losses in pipes and fittings for a variety of fluid flows.

checalc.com

Pierre

 

[lola.furtado]

Hi,
If you need to perform calculation:

CheCalc ‐ Fluid Flow

Calculation for pressure losses in pipes and fittings for a variety of fluid flows.

checalc.com

Pierre

Hi, thanks for answering!

I have to calculate the diameter of a natural gas pipe. (The pipe is coming out of a separator). I know how to do that, i’m just not sure about the temperature i should work with.

I know that the temperature of the pipe it's an ambient one, but i need to use a specific temp.

I was thinking of the extreme cases like the highest or the lowest temp. Or should i use an average one?

 

[lola.furtado]

You will need to consider both for different design reasons. If you are looking at piping stress then you will need to consider the maximum and minimum temperatures of operation of a piping system to determine the thermal expansion stress range. If you are looking at the maximum velocity in the pipe of 60 ft/sec based on noise then the velocity is maximum at the highest temperature, and pressure drop is maximum also at highest velocity. If you are looking at heat transfer and loss of heat in the pipe then the pipe will lose most heat when temperature of fluid versus ambient temperature has maximum differential. Depends on what facet of the design you are looking at.

Hi! Sorry i didn't explain it well.

I only need to calculate the diameter of a natural gas pipe coming out of a separator (in a central tank battery). To do that i'm using different equations, and for one of those i need to use a specific temperature. I know it's an ambient one, but i wasn't sure if i should use a maximum, minimum or an average temp.

 

[rb1957]

ok, not my area so this may be "uninformed" ... you have an equation that is calculating some design parameter. "which temperature is critical ?" which temperature creates the critical value of the design parameter ? But it may not be that simple ... the different temperatures may change other design parameters.

So solving your equation for both temperatures may be the minimum amount of work (but things may not change in a linear or monotonic way, and possibly you need to consider intermediate temperatures).

 

[Snickster]

I would use the temperature that gives the largest diameter.

 

[pierreick]

Hi,
This is a sensitivity analysis, perform calculation for both cases, select the one where head loss is the smallest. Criteria could be Delta P / 100 (meters or Feet) pipe length.
A good starting point could be velocity in pipe around 20m/s.
At the end, consider the pipe size available on the market to make your decision.
Good luck.
Pierre

 

[pierreick]

Hi,
Another resource to support your work.
Pierre

 

[pierreick]

other documents
Pierre

 

[lola.furtado]

Hi,
This is a sensitivity analysis, perform calculation for both cases, select the one where head loss is the smallest. Criteria could be Delta P / 100 (meters or Feet) pipe length.
A good starting point could be velocity in pipe around 20m/s.
At the end, consider the pipe size available on the market to make your decision.
Good luck.
Pierre

Thank you!

 

[lola.furtado]

ok, not my area so this may be "uninformed" ... you have an equation that is calculating some design parameter. "which temperature is critical ?" which temperature creates the critical value of the design parameter ? But it may not be that simple ... the different temperatures may change other design parameters.

So solving your equation for both temperatures may be the minimum amount of work (but things may not change in a linear or monotonic way, and possibly you need to consider intermediate temperatures).

Alright, i think i’ll just use an intermediate temperature.

Thank you!