Just a little hint here - before you ask questions, check out the other simialr questions via the search bbox at the top.

for example see http://www.eng-tips.com/viewthread.cfm?qid=348061

your veleocity isn't particularly high unless you've got hard particles in and you'ev got elbows or you're going into a tee at right angles.

Max velocity is an art not a science.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

I briefly looked at the linked post and it does not contain all of the information you need. In carbon steel tubing (I assume that is the pipe you are referencing), the rate of erosion is increased by several factors. The number of chlorides (hard particles) magnifies the rate drastically. You would need a water analysis to quantify this. Also, CO2 and H2S corrosion (pressure and temperature dependent) can speed up the rate of erosion. Do you have any other particles being produced, such as sand? Are any chemicals passed through the pipe that could alter the effect of any of the other contributing factors? Acid jobs, production chemicals? Your fluid composition is also needed to calculate your maximum velocity. Increasing fluid density lowers maximum allowed velocity quite drastically, and is only compounded by factors of CO2 and particles.

Depending on the compositional grade of the tubing, the maximum design velocities will differ. You could pay for a higher grade of tubing to delay or prevent added erosion. Another consideration is once you have erosion, your friction factor is changed and alters your critical velocity to flow or lift.

Rachel

API RP 14E 1991 has this equation for overall-mixture erosional velocity:

V_e = C / √ p_mixt

V_e = erosional velocity
C = empirical constant, 100 for continuous flow, 125 for intermittent service
p_mixt = gas/liquid mixture density, lbm/ft³

thanks all for your help, much appreciated