10% -20% Sulphuric Acid pipeline

[MTRR]

Hi!

I'm currently involved in the design of a 2" pipeline that transports 10% -20% sulfuric acid.

This line will have an intermittent service (once a month for cleaning process equipment) and must be manufactured in FRP or CPVC.

In the consulted bibliography only indicate velocities for CS and SS pipes but not for FRP and CPVC pipes.

I'm interesting to know a recommended velocities for transports 10% -20% sulfuric acid in FRP and CPVC pipes.

Thank you all!

 

[LittleInch]

They're not really any different to steel.

Anything in the range 2-3m/sec is quite normal, but up to 5-6 would be ok, especially for intermittent service, but watch out for surge issues at the higher velocities.

Pipeline implies quite a long thing so other factors such as pressure rating and pressure drop may come into play or just the sheer volume of material in the pipeline.

PVC isn't normally the best pipeline material and watch out for the connections.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[MTRR]

Thanks for your help!

 

[moltenmetal]

If this were concentrated acid, you would have very strict velocity limits for carbon steel lines. Sulphuric acid can be handled by carbon steel when it's concentrated enough, but only if there's a layer of ferrous sulphate available to passivate the inner surface of the pipe. Velocities which would be normal in piping are sufficient to strip off that layer. Even bubbles of hydrogen rising from corrosion are sometimes sufficient to strip off that layer and lead to intense localized corrosion.

At 10-20 wt% acid, you're not using metallic piping...and in plastic piping, the velocity is selected the same way you would for any fluid service. You select an economic velocity which is an optimum between the cost of piping materials and labour and the cost of pumping energy. And since those mixtures will have water-like velocities, that would put you in my rule of thumb range of around 5 ft/s on pump suctions and 10-15 ft/s on pump discharges. 5-6 m/s is pretty quick- the pressure loss per unit length would be pretty high, but the pipe wouldn't be harmed.