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Tank Cleaning Incident – 3 fatalities

This accident report was sent anonymously, and clearly demonstrates the need for a full Risk Assessment prior to certain work being carried out. The source of ignition was Hot Work on deck, which completed the dreaded fire triangle …

Date of Incident: July 2010
Incident Type: Fire & Explosion
Incident Consequence: Fatalities, Missing Crew & Structural Damage

Brief Description of What Happened and Why It Happened:

A parcel size chemical tanker was in ballast voyage and was in the final stage of tank cleaning. The next cargo parcels to be loaded included a grade requiring a high standard of Wall Wash Test (WWT). The WWT taken by the ship crew upon completion of tank cleaning revealed unsatisfactory results. The ship’s crew decided to conduct a spray in the tank with methanol to achieve the required standard of WWT.
This was conducted utilizing a portable air driven pump placed on top of the methanol drum on the catwalk in the vicinity of the tank. The pump was connected to a PVC hose serving as the discharge hose. The discharge hose connection to the pump leaked, resulting in a liquid/vapour trail reaching the source of ignition 29 meters abaft.
Upon ignition, the fire flashed back to the area where the drum of methanol was positioned in the vicinity of the cargo tank being sprayed with methanol, resulting in a subsequent explosion inside the cargo tank.

As a result of the explosion, three (3) crew members involved in the methanol spray operations were directly affected.

The first crew member inside the cargo tank and a second crew member positioned on the main deck and in vicinity of the methanol drum sustained severe burn injuries. The third crew member stationed outside the cargo tank in vicinity of the tank entrance was reported as missing and assumed fallen overboard due to the force of the explosion. The cargo tank, adjacent pair of cargo tanks, the double bottom ballast tank and the main deck was damaged structurally.

Search and rescue operations for the missing crew member were carried out by the tanker and the air & sea support vessels of the regional rescue centre for the next two and half days without any success. The two (2) crew members with severe burn injuries were medically evacuated by a helicopter to the nearest hospital and subsequently to another hospital well equipped to treat burn patients. However, these crew members succumbed to their injuries after a few days of treatment due to the extensive nature of the burns sustained.

Direct Cause:

• Unsafe conditions – Presence of fuel (from methanol spray) & a source of ignition for combustion occurring
• Unsafe act – The spray of methanol & source of ignition existed due to non-compliance of procedures, and operations conducted unbeknow to the company. Hence existing controls were violated.

Key Learning Points:

1. The underlying/root causes derived as a result of this incident are being addressed by the company. The measures deal with human behaviour and each company/organization should undertake their own methods which motivates their workforce to achieve SAFETY, through compliance with their written procedures. Addressing the “Human Element,” is a long term measure and efforts taken should be continual and conducted tirelessly.

2. The source of ignition was recognized and additional controls are being implemented to increase compliance to the working procedure. This is not being elaborated as the measures mentioned below regarding the “Fuel” part of the fire triangle takes precedence

3. In the trade practice onboard chemical tankers, it is not uncommon that the use of methanol or other chemical/detergents is undertaken to achieve the required standard of cleanliness inside the cargo tank, pipelines, cargo hoses, manifold adaptors/reducers, gauging equipment, etc. Industry publications clearly highlight and caution regarding their use due to their flammability and toxicity hazards.

4. In this particular incident, methanol was used in an uncontrolled manner without a proper risk assessment. The easy availability of methanol on board the vessel attributed to this act being undertaken. As an immediate measure, the company decided to remove all flammable solvents/detergents used for cleaning of tanks, hoses and fittings. All existing stock of such solvents/detergents from the fleet has been offlanded to shore facilities.

5. A safer alternative is being sought for the fleet to use, which are both non-toxic and non-flammable and tests are being undertaken for the various commercially available detergents/chemicals for cleaning, achieving the desired results. This may increase the time for tank cleaning but having a safer alternative clearly outweighs the risk being taken to achieve tank preparedness utilizing flammable /toxic solvents.

6. Where the nature of the last cargo requires a mandatory pre-wash or a cleaning technique with a medium other than water, a detailed risk assessment shall be conducted and controls established under close discussion with the company and such operations shall preferably be conducted in an inert atmosphere.

Perhaps then we should ask ourselves:

• Is methanol spraying allowed in your company?
•  Has a full risk assessment made before the operation?
• Are ship staff required to obtain permission from management ashore prior any such work?
• What is your company procedure if simultaneous operation (simops) are
  taking place?
• Note: In this incident it was chemical spraying in one cargo tank and
  hot work on deck.
• Are your ship staff aware of company procedures on the do’s and don’ts?

Note: In this incident in their company procedures, methanol spraying is not allowed on board and any hot work outside of engine room workshop require permission from shore management. The senior management on board and crew were aware of such a requirement however these are still being carried out onboard.

What had actually went wrong?

• Clearly there are some violation in procedures that had taken place
• Doubtful safety culture on board and most importantly
• Less than adequate enforcement of company procedure.
• Inappropriate monitoring/verification by the company regarding shipboard activities and compliance to company’s procedure.

In chemical industry practice, it is not uncommon that the use of methanol or other chemical/detergents is undertaken to achieve the required standard of cleanliness. Still some companies have total ban while others still in practice with some strict guidelines/risk assessment
in place. The particular company in this case has now learnt their valuable lesson and had infact removed all methanol on board in their fleet.

Only the use of DI water is in use now.

Download this report in PDF format

Opinion disclaimer:

Opinions expressed on this site are those of the individual contributor, and are not necessarily those of Headland Media or Walport International. Accident reports are gathered from multiple sources, and their accuracy is not warranted by the publishers of this blog.