ASTM D4929:

Standard Test Method for Determination of Organic Chlorine Content in Crude Oil

Organic chlorines do not occur naturally in crude oil. When present, they result from contamination in some manner, such as disposal of chlorinated solvent used in many dewaxing pipeline or other equipment operations.

Organic Chlorine species are potentially damaging to refinery processes. Hydrochloric acid can be produced in hydrotreating or reforming reactors and the acid accumulates in condensing regions of the refinery. Unexpected concentrations of organic chlorides cannot be effectively neutralized and damage can result. Organic chlorides are not known to be naturally present in crude oils and usually result from cleaning operations at producing sites, pipelines, or tanks. It is important for the oil industry to have common methods available for the determination of organic chlorides in crude oil, particularly when transfer of custody is involved.

Organic Chlorine present in the crude oil (for example, methylene chloride, perchloroethylene, etc.) is usually distilled into the naphtha fraction. Some compounds break down during fractionation and produce hydrochloric acid, which has a corrosive effect. Some compounds survive fractionation and are destroyed during hydro-treating (desulfurization of the naphtha).

Other halides can also be used for dewaxing crude oil; in such cases, any organic halides will have similar impact on the refining operations as the organic Chlorines.

ASTM D4929 method Procedure B covers the determination of organic Chlorine in the washed naphtha fraction of crude oil by oxidative combustion followed by microcoulometric titration.

To comply with ASTM D4929, TSHR offers Total Chlorine TX 6000 and TX 7000 series models with oxidative microcoulometric titration and combined instrument configurations like TN/TX 6000 and TS/TX 6000 models with semi-automatic syringe or fully automatic liquids injection through HR 7000 models Liquids Autosampler configurations for trace level Total Chlorine analysis.