Tag: HCl Corrosion

Hastelloy C276 Bolts or Duplex Bolts for Waste Water HCl Injection

Q: We’re making some changes in our waste water treatment process and are going to using hydrochloric acid (HCl) as a means of lowering the pH levels. Will I need to upgrade my duplex bolting?
A: Assuming your waster water is at ambient temperatures the only thing you need to worry about is the concentration of the HCl. By your inlet, it may be highly concentrated requiring different bolting further upstream than down stream.  Depending on the your PH, you certainly will be safe with Hastelloy C276 bolts by the injection ports. Further downstream you will probably be OK with duplex bolts as the acid injected dilutes out.

Bolts for Steel Pickling in HCl: Hastelloy and Tantalum

Q: I’m using HCl in a pickling process and have used Hastelloy C276 bolts to protect my equipment but am still having corrosion issues. Any ideas?
A: In pickling processes ferric chloride is created which is a strong oxidizer and most pickling process are at elevated temperatures – Hastelloy C276 doesn’t perform well in strong oxidizers. Steel placed in HCl, not only removes rust but creates a chemical reaction where iron combines with chlorine in HCl, making FeCl3. To prevent corrosion from both the hydrochloric acid which is a strong acid and the ferric chloride which is a strong oxidizer, you may want to try Hastelloy C2000 bolts or tantalum bolts. Hastelloy C2000 features strong acid protection of C276, plus its very resistant to oxidizers. Tantalum is the ultimate for corrosion resistance in HCl pickling process but offers less strength.

Hastelloy fasteners for HCL & H2SO4 in Municipal Waste Incinerator

Q:  I’m running a municipal solid waste incinerator and am having trouble corrosion from a combination of hydrochloric acid and sulfuric acid that is derived from chloride and sulfur containing compounds in the waste fuel stream. I was using Duplex steel bolts for the chloride corrosion but they aren’t holding up with the condensation of HCl.

A:  Your biggest problem when dealing with hot chlorine and sulfur compounds is when they cool and combine with moisture to create HCl and H2SO4 acids. These droplets of acid could also get very concentrated as the moisture is evaporated off.  I would suggest a high performance nickel alloy fastener like Hastelloy C276. In regards to chloride corosion, Hastelloy should work very well in this kind of environment and is stable at elevated temperatures.  You learn more about Hastelloy C276 fastener by following this link.