Tag: Hastelloy fasteners 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.

Hastelloy C276 Bolts – Sulfuric Acid Condensation

Q: I have a situation where I’m not only dealing with a hot steam environment which  can reach 700F but there is also sulfuric acid condensation that can form during cool down periods. Are their any materials that can handle heat and corrosion?

A: Typically when dealing with sulfuric acid one of the best go-to materials is Hastelloy. Hastelloy C276 bolts in particular are a good choice for acid condensation as the the acid droplets could become highly concentrated. As Hastelloy C276 bolts provide excellent corrosion resistance to sulfuric acid through a wide range of concentrations and temperatures, condensation won’t be a problem. In addition, Hastelloy C276 fasteners can withstand hot environments, retaining their strength to about 1500F.