The ship’s welder opened the Oxygen and Acetylene gas bottle valves in order to do a cutting job on deck. These gas bottles were attached to the vessel’s integrated welding gas system. Opening the valve on the Oxygen bottle had the immediate effect of causing an explosion to a short, high pressure hose delivering oxygen from the bottle to the oxygen gas regulator. The end of the hose caught fire and was quickly extinguished by turning off the oxygen bottle. Nobody was injured and the only damage was to the hose that completely separated.
What went wrong?
Investigation found the following:
- The hose had been recently replaced, but the replacement hose was a hydraulic oil service hose with oxygen fittings. The replacement hose was not compliant with the ISO 14113 specification required by the manufacturer, although the pressure rating was suitable;
- The non-compliant hose was supplied from a non-preferred supplier (the required hose length was not available from original supplier);
- The onboard team did not adequately check that the hose was of the correct specification.
What was the cause?
Based on detailed investigation into a similar incident, it was suggested that the cause of the incident was due to adiabatic compression heating within the hose which caused the inner lining to auto-ignite due to residual oil within the hose. Our member notes that there are numerous incidents recorded by industry due to this issue.
What actions were taken? What lessons were learned?
Welding hoses should be compliant with ISO 14113. For oxygen hoses, the material should have an auto-ignition temperature suitable for the service (typically > 400â°), and cleaned for oxygen service.
- Do not assume that because a hose is sufficiently pressure rated it is fit for a specific purpose.
- Always ensure correct specification hoses are ordered and received.
IMCA notes that in order to avoid adiabatic compression:
- Use only original equipment and spares when handling/servicing oxygen equipment;
- Work clean – no oil or any other hydrocarbon impurities must contaminate the parts (your hands, tools etc.);
- Open oxygen cylinder top valves slowly.
Members may wish to refer to the following incidents:
IMCA Safety Flashes summarise key safety matters and incidents, allowing lessons to be more easily learnt for the benefit of all. The effectiveness of the IMCA Safety Flash system depends on Members sharing information and so avoiding repeat incidents. Please consider adding [email protected] to your internal distribution list for safety alerts or manually submitting information on incidents you consider may be relevant. All information is anonymised or sanitised, as appropriate.
IMCA’s store terms and conditions (https://www.imca-int.com/legal-notices/terms/) apply to all downloads from IMCA’s website, including this document.
IMCA makes every effort to ensure the accuracy and reliability of the data contained in the documents it publishes, but IMCA shall not be liable for any guidance and/or recommendation and/or statement herein contained. The information contained in this document does not fulfil or replace any individual’s or Member's legal, regulatory or other duties or obligations in respect of their operations. Individuals and Members remain solely responsible for the safe, lawful and proper conduct of their operations.