Critical H2S Safety Support During Subsea Shutdown in the Norwegian Continental Shelf

Client/Project Overview

A client operating in the Norwegian Continental Shelf scheduled a shutdown to repair and upgrade six valves located in oil-bearing storage cells, 200 meters below sea level. The area was classified as Zone 1 — a high-risk environment where explosive atmospheres are likely due to dangerous gas concentrations.

Needs and Challenges

• High concentrations of H2S expected in ballast water

• Risk of toxic gas release during subsea operations

• Need for continuous gas detection and personnel protection

• Complex logistics involving underwater storage cell emptying and tanker transport

• Safety assurance in a Zone 1 classified environment

Key Tasks Executed

• Deployed six H2S safety supervisors to the offshore installation

• Provided 24/7 monitoring and support throughout the shutdown

• Supplied and operated advanced gas detection and protection equipment

• Oversaw safe transfer of storage cell contents to tanker vessel

• Conducted real-time H2S concentration measurements during transport

Solutions Implemented

• Delivered expert supervision and equipment tailored for high-risk H2S environments

• Maintained continuous presence to ensure immediate response to any gas leak

• Enabled safe execution of valve upgrades and fluid transfer under hazardous conditions

• Applied rigorous safety protocols to mitigate exposure risks

Results Achieved

• Successfully detected and managed H2S concentrations exceeding 5,000 ppm

• Prevented potential exposure incidents in a deadly gas environment

• Ensured full protection of all personnel involved in the operation

• Delivered a life-saving service that enabled the project to proceed safely and efficiently