• Published: 3 Oct 2011
  • Incident ID: 3389

H2S Exposure – Failure to Follow Proper Procedure

Cause & Consequence

  • Drowned or asphyxiated
Incident Consequence

Incident Location

Onshore construction/rig repair yard

Incident Activity


Incident Info Source


Specific Incident Equipment

No specific equipment involved in this incident

Lessons Identified

The immediate causes of the incident are:

  • Opening the thief hatch (inattention to job hazards): all workers on site were made aware of the presence of H2S and that venting to atmosphere or opening up the thief hatch would release large amounts of H2S.
  • Failure to follow procedures: there were company/ industry standards and training that stressed the hazards and enforced that H2S was not allowed to enter the atmosphere. These procedures were not followed, when the supervisor opened up the thief hatch.

Underlying Causes of the Incident are:

  • Complacency: It is believed that complacency in routinely working around sour gas is a contributing factor to this incident. The fatally injured supervisor was aware that opening the thief hatch would allow large volumes of H2S to be released to atmosphere.
  • Failure to Refuse Unsafe Work: The contract workers on site should have refused to perform unsafe work.
  • Insufficient Planning: This type of work requires equipment to scrub out the toxic gas or contain it. The supervisor and the contract company did not have the proper equipment in place as required by company, industry and regulatory standards.

Incident Recommendations

Increased Supervision and Inspections:

The company has hired additional staff to complete inspections and field audits on all third party contractors and supervisors. These inspections are to ensure that

  1. Proper safety equipment is in place and being used,
  2. To ensure that all workers are aware hazards and are following the policies and procedures in place,
  3. To ensure that no unsafe decisions are made.

Annual HSE Orientations for Company Representatives:

The goal of this additional program, beyond the company’s existing regular annual orientations completed with all workers is to focus on prime representatives or supervisors leading a project for the company in the field.

The company needs to ensure that all those in a supervisory role are aware of the HSE programs in place. These supervisory personnel must also have the knowledge and resources to ensure any work being done on a job site are done to the highest safety standards.

The intent is to prevent unsafe decisions being made in the field.

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