Tag: Alloy 20 for sulfuric acid

Alloy 20 vs. Hastelloy C27 Bolt for H2SO4

Q: I have a hot sulfuric acid application that utilizes approximately 25-32% sulfuric acid. I really need a corrosion resistant bolt but due to the vastness of the operation, I’m wondering if there is a lower cost option than Hastelloy.
A: For hot sulfuric acid in your concentration range, we would need to know the operating temperature to make a recommendation. However generally the most economic option would be Alloy 20 bolts, but for Alloy 20 bolts to be successful in your application the temperature would need to be below 150F.  Beyond 150F, you are better off with Hastelloy C276 bolts otherwise you will suffer a significant corrosion rate in Alloy 20 and likely premature failures.

Alloy 20 Bolts for Sulfuric Acid (H2SO4)

Q:
I’m running a cotton mercerizing process that is being altered to utilize sulfuric acid. I didn’t realize how corrosive using sulfuric acid (H2So4) is on my fasteners. Any ideas on how to protect my bolts. Not super hot, just corrosive.
A:
Alloy 20 bolts are a good choice for this. It was specifically designed for use in hot sulfuric acid, easily handling boiling sulfuric acid in 20% to 40% concentration, as well as general sulfuric acid resistance. If Alloy 20 bolts do not do the trick then you can up your resistance to Hastelloy C276 bolts which are ideal for use in hot sulfuric acid at higher temperatures and concentrations than Alloy 20 fasteners.