Hot Acid Piping Materials 1

[MidstreamEgr]

Looking for any recommendations for research on piping for a low pH hot system. It's ~1-2pH and 180-225degF. They currently use carbon steel and replace spools often, which may be more cost effective than an exotic material. But this has to be relatively standard operation conditions in sulfuric acid plants, refineries, etc. Flowrate is around 100gpm and piping is ~3"-4", so tubing won't work. Low pressures up to 125psig.

Thanks in advance!

 

[SJones]

http://www.ddpsltd.co.uk/pipes-valves-and-fittings,49925/

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

All answers are personal opinions only and are in no way connected with any employer.

 

[MJCronin]

I would consider PTFE lined systems....but they are expensive.

http://www.cranechempharma.com/chempharma/brand/resistoflex.

How much CS piping is being replaced ? How often ?

Is the piping exhibiting classic "grooving" failure at the 12:00 o'clock position ?

Are you using schedule 80 ( or thicker) piping ?

Tell us more...

 

[Compositepro]

Glass-lined steel pipe and vessels should work nicely. It been around for 100 years. Just don't take a hammer to it. It is basically an enamel coating.

 

[moltenmetal]

Another vote for PTFE lined here. Temperatures are low but just not low enough for plain carbon steel. 100 gpm in 3-4" pipe sounds like your velocity is a little high- carbon steel is passivated by a ferrous sulphate layer which can be stripped off by normal fluid velocities and even by gas bubbles- hydrogen generated by corrosion.

 

[EdStainless]

3"-4" is still tubing, especially since you have such low pressures.
With the right alloy you will have zero corrosion allowance.
Walls of 0.065" - 0.083" would be suitable.

What acid is it and what is the total halide content?

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Plymouth Tube

 

[MidstreamEgr]

The product is a mix of sulfuric acid, suspended solids (metals), water, and oils. Flow (fps) can be whatever we want, since we're designing a new system - we'll target 8fps max and 5-6fps normal operating. Don't know halide content unfortunately.

I like what I've found on PTFE lined pipe, and cost seems reasonable (compared to exotic metals). My only concern is abrasive wear from TSS metals, but we can limit that with moderate velocities.