Chloride cracking

Once the principal route to vinyl chloride, in all but a few percent of current U.S. capacity this has been replaced by dehydrochlorination of ethylene dichloride. A combined process in which hydrogen chloride cracked from ethylene dichloride was added to acetylene was advantageous but it is rarely used because processes to oxidize hydrogen chloride to chlorine with air or oxygen are cheaper (7) (see Vinyl polymers). 

Virtuallv evety alloy system has its specific environment conditions which will prodiice stress-corrosion cracking, and the time of exposure required to produce failure will vary from minutes to years. Typical examples include cracking of cold-formed brass in ammonia environments, cracking of austenitic stainless steels in the presence of chlorides, cracking of Monel in hydrofluosihcic acid, and caustic embrittlement cracking of steel in caustic solutions. 

The types of corrosion experienced in the chemical manufacturing industry, the petrochemical manufacturing industry, and the pharmaceutical manufacturing industry are similar in many respects. The most common types of corrosion encountered are caustic and chloride cracking, oxidation, sulfidation, corrosion under thermal insulation, ammonia cracking, and hydrogen-induced cracking. 

In the aged condition, the alloy is resistant to chloride cracking. Its corrosion resistance, in general, is on a par with tiiat of type 304 stainless steel. 

Alloy X has excellent resistance to nitric acid, organic acids, alkalies, salts, seawater, chloride cracking, and good to excellent resistance to phosphoric and sulfuric acids, with good resistance in hydrochloric and hydrofluoric acids. 

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