A company charged with violating Saskatchewan's Occupational Health and Safety Act after one man died on the job is in an Estevan court this week.

Oil company Nalco Champion employed Michael Bunz, 38, at the time of his death in 2014 near Kipling. Bunz had died from asphyxiation from chemical exposure.

Bunz was collecting samples, something he had done more than a thousand times before, when a ball valve failed and released toxic levels of hydrogen sulphide into the room with him.

Bunz worked as a contractor, selling chemicals to the oil industry in southeast Saskatchewan. As part of his work he would regularly do testing at well sites.

About 15 witnesses are expected to testify during proceedings.