Corrosion in Hydrochloric Acid
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Corrosion in Hydrochloric Acid (HCl)

 

Hydrochloric acid is a solution of hydrogen chloride (HCl) in water, that is a highly corrosive, strong mineral acid with many industrial uses.

At lower temperatures plastics or polymer lining like PTFE or PVDF lining may be a cost efficient way to avoid corrosion. At temperatures above 150 °C / 300° diffusion through the polymer materials becomes significant and plastic lining is in general not suitable. At these temperatures the mechanical properties of polymer lining may be poor, forcing engineers to consider metal based solutions.

Due to the potentially strong reactions between chloride ions and the base metal, the concentration and temperatures of hydrochloric acid needs to be known to determine if the metal will survive and have an acceptable corrosion rate. The iso-corrosion chart shows the relative corrosion resistance of several specialty alloys and exotic metals in various concentrations and temperatures of hydrochloric acid (hydrogen chloride). Such alloys will typically be applied when stainless steel shows insufficient corrosion resistance in hydrochloric acid. It can be seen that the corrosion attack of hydrochloric acid, as with most acids, is highly dependent on the temperature. Chloride containing acids will in many situations show a corrosive nature similar to hydrochloric acid at comparable acid and/or chloride concentrations.
 

Hydrochloric acid iso corrosion chart

Hydrocloric Acid corrosion charts. The corrosion resistance of Titanium, Zirconium, Nickel alloy (Hastelloy), niobium and Tantalum. A corroion rate higher than 5 mpy in hydrogen chloride is not above practical acceptance limits for valves in Hydrochloric
Hydrochloric Acid Iso Corrosion Curves for Hastelloy (nickel alloy), Titanium, Zirconium, Noibium and Tantalum.
 
 
Compared with other specialty metals and alloys like Hastelloy, niobium and zirconium, the corrosion resistance of tantalum metal is second to none in hydrochloric acid. Tantalum metal is an element (atomic number 73) and is considered to be the most corrosion resistant metals commercially available. At temperature less than 150C and a concentration less than 30%, tantalum is considered to have a nil corrosion rate or less than 1 mil/year in chlroride acid service.
 
For precision parts such as valves, fittings and instrumentation where tolerances are critical to their operation, a corrosion rate 5 mil/year or larger would typically be considered unacceptable in hydrochoric acid applications.

The table below shows the relative corrosion resistance in hydrochloric acid at concentrations in the range 5 to 35% and temperatures up to 200C. As can be seen, Tantaline has superior performance over niobium, zirconium and nickel based alloys.
 


 
*) Hastelloy is a trademark of Haynes International
 
Guide to Hydrochloric Acid (HCl) Resistant Products
 ► Agitators 
 ► Autoclaves 
 ► Bellows 
 ► Couplings 
 ► Earthing Rings 
 ► Expansion Joints 
 ► Fasteners  
 ► Fittings, Pipe 
 ► Fittings, Tube 
 ► Flanges  
 ► Grounding Rings 
 ► Heat Exchangers 
 ► Instrumentation  
 ► Laboratory Reactors  
 ► Level Sensors  
 ► Orifice Plates  
 ► Pipe Fittings 
 ► Pumps 
 ► Static Mixers 
 ► Stirrers  
 ► Thermowells 
 ► Tube Fittings 
 ► Valves 
 
Customer Testimonial - Performance (2:24)
Click to view General Atomics experience with Tantaline
 
Performance Data
See Tantaline vs Coatings in:
 > Chlorine Gas
 > Sulfuric Acid
 > Liquid Bromine
 
Link to Corrosion Data on Metals in Hydrochloric Acid

Select the way you want to see the Hydrochloric Acid Corrosion Data:

> As ISO corrosion CURVES
> As TABLES

 

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