Pipe sizing, pressure drop for fluids

[engr2GW]

Hi all,

1. in sizing piping for gas, liquid or mixed flow, for plant or facility piping, is there a guide for limits or ranges to keep:
a. total dP (psi)
b. dP/100 ft of piping
c. Velocity (ft/s)

Is there any other major factor or property that should be kept in mind?

2. Also: if one does not have a computer program or somekind of tool, and wants to do the calculation from the equations. Which of the equations will be better for
a. gas
b. liquid
In most cases, I'll have the P1, Q, S.G, density, fluid properties, T, pipe lenght, number of fittings, etc.

3. when you have bends, 90s, 45s, Tees, valves, etc. how do you incoporate that into the total lenght of the pipe, is there a rule of thumb?

4. effect of elevation on a gas piping is usually negligible, how do you incoporate elevation for liquid piping?

thanks a lot for your input.

As much as possible, do it right the first time...

 

[SNORGY]

engr2GW,

thread798-339048

The above thread discusses this to some extent. I highly recommend getting:

Crane Technical Paper TP 410 and / or TP 410 M, depending on what units you like.
Cameron Hydraulic Data (Ingersoll-Rand)

The first reference is found at the Flow Of Fluids website for about $60.00. The latter is out of print and harder to find.

 

[rmw]

You are also going to need a source for the properties of your fluid, density, viscosity in particular. I can take a Crane and Excel and be calculating pressure loss before the kids can get something like Flowmaster set up.

To answer one of your questions, if you keep your liquid velocities under ~15 feet per second your pipe losses will be reasonable.

rmw

 

[engr2GW]

thanks all.
@rmw; I assume that your recommendation of ~15ft/s is for liquids, is there a rule of thumbs for gases?

As much as possible, do it right the first time...

 

[BigInch]

30-40 fps for gas, but it also depends on what you are trying to do with them. Oxygen speeds need to be kept lower to avoid sparking from particle impact against steel pipe, etc.

Independent events are seldomly independent.

 

[TD2K]

I look at two factors, the total dP and velocity for inplant piping.

For example, if I'm running a cross plant steam header, I'm going to go with a lower velocity and pressure drop because I want users at the far end of the plant to still receive steam at the design supply pressure. However, a lateral supplying steam to an individual steam turbine might be much higher velocity because the dP over that length of pipe could still be low even at 100 ft/sec. Larger lines can also handle higher velocities for the same dP per 100'.

 

[engr2GW]

Thanks all,

I should have mentioned that this is oil and gas piping, so the gas in question will be natural gas in facility/well site piping.
thanks.

As much as possible, do it right the first time...

 

[SNORGY]

Be careful with well site piping if the gas is laden with sand or particulates. Without going into a lot of detail explaining it, my rule of thumb would be that if you are solids-laden, use sizing criteria for the flow velocity upper limit based on API 14E and then go up one nominal pipe size from that.