Case Study involving DMDS Chemical

Incident

The incident took place on 30th May, 2008 at 1:30 a.m while the maintenance crew was connecting the DMDS (Dimethyl Di Sulfide) barrel.

After providing necessary connections, the maintenance technician inadvertently opened the N2 blanketing valve to the DMDS barrel leading to pressurizing of the system.

This led to the bulging of the bottom of the barrel and subsequent burst opening of the barrel lid at its seam joint.

Incident

As a result, the chemical DMDS splashed on the technician After giving initial medical aid in the Refinery OHSC , the said technician was shifted to hospital along with the contract worker , who also received some splash of the chemical on his body.

The maintenance technician succumbed at @ 2:45 a.m. while the contract worker was discharged from the hospital at @ 11:00 a.m. on 30th May itself

Drum is elevation storage vessel at ground level

Lid of drum thrown out

drum

Incident Analysis

Maint Technician operated the valves on Nitrogen blanketing system as well on DMDS barrel decanting system without authorization and in absence of the Operating personnel.

After connecting DMDS barrel, bottom of the barrel bulged and the lid got opened at the seam and the rest of the body of the barrel was thrown away at a distance of about 3 meter.

Incident Analysis

Due to lack of thoroughness in the venting system, the unloading facility of the DMDS got pressurized beyond the designed pressure of the barrel.

Incident Cause :

Unauthorized lining up of the DMDS barrels by the technician, without knowledge of the operating system and possible hazards.

Recommendations

The departments to work within their own domain of skill.

The thoroughness of the system including NRV to be positively ensured and documented.

Since the Nitrogen line up is only for blanketing and the system is not designed for Nitrogen header pressure, Pressure Reducing Valve should be considered for installation u/s of the N2 blanketing system. This will act as a additional safeguard for avoiding system getting pressurized.

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