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Topic: What would be the ideal material of construction for a hydrochloric acid plant?

anonymous
What would be the ideal material of construction for a hydrochloric acid plant? Would you recommend using galvanized steel, which is painted with three layers ( two epoxy + one final coat of acrylic), the total thickness is maxi 180 μm?
  • Avatar Brian Dalder Forum Moderator 177 Posts

    Re: What would be the ideal material of construction for a hydrochloric acid plant?

    From your question it sounds like you are talking about a plant that manufactures hydrochloric acid. This is a complex operation and might involve the use of several different materials of construction depending on the specific equipment in question. However, some general advice can be given regarding the appropriate materials of construction for hydrochloric acid service.

    Most metallic materials are not compatible with hydrochloric acid including aluminum alloys, iron and steel, galvanized steels, and stainless steels. Hastelloy alloy B-2 has some resistance as long as oxidizing impurities are not present. Ni-Cr-Mo alloys like the Hastelloy C family can be used in some applications as long as the concentrations and/or temperatures are not too high. Tantalum offers good resistance to hydrochloric acid but it is expensive. In general, nonmetalic materials have better resistance to hydrochloric acid than metallic materials. Rubber-lined vessels are commonly used for hydrochloric acid storage. Polypropylene, PVC, PTFE, FEP, PFA, ECTFE, PVDF, and FRP can be used as long as long as recommended temperature limits are followed. While some paint/coating systems may be acceptable they are prone to damage and can allow hydrochloric acid to reach the substrate which is often not compatible. There are many good references available that can provide more detailed information. Examples include MTI Publication MS-3, "Materials Selection for Hazardous Chemicals: Hydrochloric Acid, Hydrogen Chloride and Chlorine" and "Corrosion by Hydrogen Chloride and Hydrochloric Acid" in ASM Handbook Volume 13C, Corrosion: Environments and Industries. For more information on coatings, a good place to start would be Schweitzer's "Corrosion of Linings and Coatings," which is one volume of the three volume Corrosion Engineering Handbook (2nd Edition) set.
  • Avatar Terry Jones Community Member 2 Posts

    Re: What would be the ideal material of construction for a hydrochloric acid plant?

    Last edited: 8 November 2012 at 5:34pm
    I am not that sure about the part in which you're talking about Hastelloy's resistance to corrosion. After all, almost all nickel-based alloys (Hastelloy B-2 being one of the most basic examples of that sort,) are renowned for their outstanding resistance to corrosion.
  • Avatar Brian Dalder Forum Moderator 177 Posts

    Re: What would be the ideal material of construction for a hydrochloric acid plant?

    Last edited: 11 January 2013 at 10:31pm
    Nickel based alloys, such as the Hastelloy B and C families, are known for their corrosion resistance. However, they are not immune to attack by hydrochloric acid. And the degree of corrosivity will depend on such things as concentration, temperature, degree of aeration, and what impurities are present. For example, the corrosion rate of Hastelloy B-2 in 20% HCl at 80 deg C is 5-20 mpy under a nitrogen sparge but 20-60 mpy in an aerated solution. The major weakness of Hastelloy B-2 is that its corrosion resistance decreases dramatically under oxidixing conditions. So it is strongly recommended that Hastelloy alloys be tested with as-welded coupons under actual plant conditions before selection for any hydrochloric acid service.
  • Avatar Narendra Thakkar Community Member 1 Post

    Re: What would be the ideal material of construction for a hydrochloric acid plant?

    DuPont promote large quantity of Teflon(r) ( PTFE/PFA) for HCL handling application through processors. In india major market is for Lined pipes and Teflon(r) PFA Lined Valves.
  • Avatar Bruno Anjos Community Member 1 Post

    Re: What would be the ideal material of construction for a hydrochloric acid plant?

    And talking about hydrochloric acid at very high temperature (190°C)? Besides tantalum, that is so expensive, is there another material that can be used? I've heard about silicon carbide (SiC). Do you have any corrosion data for it? Consider I am talking about diluted (14%) and concentrated (33%) hydrochloric acid . Thank you.