Corrosion resistance of 304SS to dilute 0.04% sulfuric acid 3

[bh1]

I have read the stainless and sulfuric acid posts and looked at the references out of them.

The charts and articles I have found seem vague at these low concentrations. In your opinions is 304L SS piping acceptable in a 0.04wt% sulfuric acid stream at 120 deg F? Are there any specific references I should use for data at this concentration.

Thank you.

 

[kenvlach]

Looks OK [unless very high flow erodes the protective surface film on the metal]:

http://www.sulphuric-acid.com/techmanual/Materials/materials_metals_304.htm

Flow rate matters (note, quote is for concentrated sulfuric at ambient T):
"The materials of construction for piping are dependent on fluid flow velocities and quality concerns. In general, seamless carbon steel piping is used for flow velocities between 1-3 feet per second (fps). 316 SS is acceptable for flow velocities of 0-8 fps. Alloy 20 works for flow velocities of 0-20 fps, and Teflon®-lined pipe works for all ranges of fluid velocity. If iron contamination is a concern for the process, stay away from carbon steel. These recommendations assume ambient temperatures. All metal piping should be welded per "ANSI B31.3 - Normal Service" specifications. Screwed fittings are discouraged. PVC and CPVC piping is recommended for vent/vapor lines only. They are not recommended for liquid service."

http://www.dupont.com/sulfurproducts/techdata/equipment.html

For dilute solution at 120 ^oF, why not use CPVC?

 

[EdStainless]

In Paul Dillon's book on Corrosion Control in the CPI there is a table (23.2 on page 252). It lists Sulfuric acid, 0.05% at 95C, and the corrosion rate for 304 and 316 are both given as zero.
It should be noted that the presence of any chlorides will tip things in favor of 316.

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Rust never sleeps
Neither should your protection

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[bh1]

thank you. I will find out what my clients line size is going to be. I will also check on the chloride issue. that is what made me concerned about 304 in the first place. May have them consider CPVC but this piping run has some potential support limitations which could be problematic.

 

[joeswoes]

go with composites, corrosion resistant to sulfuric and chlorides and do not require anywhere near the amount of pipe supports as CPVC.

 

[DaveStearns]

You might want to consider ECTFE coated (inner) sched 10 steel pipe with 150 lb flanges manufactured by Fabtech. It should handle both.