Flow rates in H2SO4 1

[JonD71]

I currently have an issue where an H2SO4 - 98% >70 deg C line has eroded at elbows/welds etc from flow induced erosion due to the velocity and volume of acid travelling through the pipe. I am looking to replae this line though currently have conflicting advice on maximum allowable flows prior to the onset of internal flow induced erosion. The max ranges I have been given for carbon steel are 0.6 - 1.0m/s and for 316L are 1.0-2.0m/s. Anybody have any experience with this.

Regards and many thanks

JonD

JonD 71
Australia

 

[Latexman]

Contact the H2SO4 supplier/manufacturer. They are probably the experts.

Good luck,
Latexman

 

[ApC2Kp]

JonD71,
The 70 deg C is higher than typically used with carbon steel piping, where 50 deg C is considered the upper limit. The velocity limit for carbon steel piping would be 0.6 m/s for smaller piping sizes where turbulence is more of a factor. The use of 316L pipe would allow velocities of 3 m/s but still limiting temperature to 50 deg C. The corrosion rate might be 0.13 mm/yr @ 50 deg C, and increases to 0.51 m/yr @ 70 deg C for the 316L stainless.
Temperature and acid concentration are prime considerations for choosing materials of construction for acid service. If your acid temperatures are consistently more than 70 deg C, then contact John Woodhead at jrwoodhead@sesptyltd.com.au and he can tell about acid services as high as 210 deg C.

 

[BenThayer]

there are other threads on this subject that confirm what you have been told.

http://www.eng-tips.com/viewthread.cfm?qid=103747

you might try more searches on the site.

 

[DLANDISSR]

JonD71:

There is no material which will handle H2SO4 at all concentrations and temperatures.

Teflon will handle H2SO4 at all concentrations up to 400F.

The only metallic material suitable for H2SO4 is Hastelloy B
It is good for 90% to 100% concentration up to 302F(150C).

This information is per: CHEMICAL RESISTANCE GUIDE FOR METALS AND ALLOYS BY KENNETH M. PRUETT PUBLISHED BY COMPASS PUBLICATIONS