## Pipeline surge pressure

## Pipeline surge pressure

(OP)

I have an equation for surge pressure from 'Mechanics of Fluids' - BS Massey, which gives

Ap = p.c.U

Where Ap is surge pressure

p is fluid density

c is speed of wave propogation

U is change of velocty

In my case the fluid is NATO F34 so p is 775 - 840 kg/m3 (I have used 800)

I have calculated c as 713m/s

and change of velocity is 3m/s to 0.

My problem here is with units as I was never very good with maths - I get my answer as kg/m/s2 which doesn't relate to a pressure or a force as far as I know. If I could get to kg.m/s2 I would have a force which would be OK.

Now, all the surge pressure equations that I can find on the web relate to water-hammer and are in the form Ap=c.U.g where g is gravity.

Can someone tell me what I am doing wrong?

Ap = p.c.U

Where Ap is surge pressure

p is fluid density

c is speed of wave propogation

U is change of velocty

In my case the fluid is NATO F34 so p is 775 - 840 kg/m3 (I have used 800)

I have calculated c as 713m/s

and change of velocity is 3m/s to 0.

My problem here is with units as I was never very good with maths - I get my answer as kg/m/s2 which doesn't relate to a pressure or a force as far as I know. If I could get to kg.m/s2 I would have a force which would be OK.

Now, all the surge pressure equations that I can find on the web relate to water-hammer and are in the form Ap=c.U.g where g is gravity.

Can someone tell me what I am doing wrong?

## RE: Pipeline surge pressure

That said,

First: Use 840.

You don't really want force either. Force/area would be good, as would Head suffice, or its equivalent Pressure. Those are the units you need to arrive at the correct answer.

Lastly, do not use the total closure time of your valves. Use the effective time. Be aware of how much flow cutoff you are getting at various positions of valve travel and take the effective valve closure time accordingly.

It would be helpful if you would post the equation you are using to figure out why the units are going wrong. Can't say the same about the analysis.

Now find somebody who can give you some training and most importantly someone who can check your work.

Going the Big Inch!

http://virtualpipeline.spaces.msn.com

## RE: Pipeline surge pressure

Going the Big Inch!

http://virtualpipeline.spaces.msn.com

## RE: Pipeline surge pressure

I've used both max and min values of density.

I'm not actually carrying out a surge analysis by your definition. I am attempting to quantify an 'order of magnitude' for anchor loads in unstable ground, not really the same thing and perhaps my query title was misleading.

I'll keep searching.

## RE: Pipeline surge pressure

Going the Big Inch!

http://virtualpipeline.spaces.msn.com

## RE: Pipeline surge pressure

PTH001,

kg/(m.s

^{2}) is a unit of pressure. See, please,• force : m.a = kg.m/s

^{2}• pressure = force÷area = (kg.m/s

^{2})÷m^{2}= kg/(m.s^{2})^{2}= 1 Pa = 1 kg/(m.s^{2})## RE: Pipeline surge pressure