Rupture Disc Corrosion
Rupture Disc Corrosion
(OP)
I have experienced pitting corrosion of nickel rupture disc protecting anhydrous ammonia pressure vessel. EDS lab test indicates high amounts of chlorine at the pits. The source of the chlorine is unknown at this time. No other elements of any amount are present. Would chlorine cause the corrosion in an anhydrous ammonia gas atmosphere? During installation, water could possibly contaminate the area of the pipe where the rupture disc is installed.
Alternately,would ammonia cause corrosion of the nickel, possibly in combination with water as above. Also, present is stainless steel, carbon steel, rust in the pipe.
Just trying to pin down the source of corrosion. The chlorine shows up on some of the new nickel discs also.
By in large, the nickel discs are trouble free except for a few unexplained installations. Bad batch of nickel discs?
Any help appreciated.
Alternately,would ammonia cause corrosion of the nickel, possibly in combination with water as above. Also, present is stainless steel, carbon steel, rust in the pipe.
Just trying to pin down the source of corrosion. The chlorine shows up on some of the new nickel discs also.
By in large, the nickel discs are trouble free except for a few unexplained installations. Bad batch of nickel discs?
Any help appreciated.





RE: Rupture Disc Corrosion
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RE: Rupture Disc Corrosion
I don't understand where the chlorine would come from. Are you sure that this is not chloride ion. If it is chloride, then the formation of hypochlorous acid could not occur so the distinction is important.
Chlorine is a diatomic molecule, i.e., two atoms join to form the chlorine molecule. Chloride is a single negatively chaged ion.
RE: Rupture Disc Corrosion
Do you have an understanding of the EDS (Energy Dispersive X-ray Spectrometry) technique? If not, what you should understand is that it detects the presence of a chemical element, whether it exists as an ion or as the diatomic molecule in the case of chlorine. Most likely the chlorine is present as an ion, introduced from chlorinated water or some type of salt contamination during coating, transportation, etc.
RE: Rupture Disc Corrosion