Thermal Oil Heater Explosion Onboard Oil Tanker – Investigation Report

This investigation report refers to the explosion of two oil-fired thermal oil heaters onboard an oil tanker. The explosion seriously injured three crew members and severely damaged the thermal oil heater and surrounding equipment and fittings. The injured crew members received only rudimentary first aid on board. Shore-based emergency paramedics attended the ship and the injured crew members were evacuated by helicopter for treatment and recuperation.

Accident timeline

10 January 2011. During the evening Qian Chi arrived off Brisbane, Queensland following a voyage from Port Botany, New South Wales.

10 January 2011, 2240 hours. A Brisbane harbour pilot boarded the ship and following a master/pilot information exchange, Qian Chi began the 5 hour pilotage of Moreton Bay to its berth in the Brisbane River.

11 January 2011, 0500 hours. The ship was all fast alongside the Pacific Terminals wharf (see figure below).

11 January 2011, 0805 hours. Cargo operations commenced and discharge of diesel and unleaded petrol continued without incident throughout the morning. At this time, Brisbane and the surrounding area was receiving heavy rainfall and consequent flooding. The resulting strong current within the Brisbane River led the regional harbour master to close the port to all traffic. All ships in the port were directed to evacuate to Brisbane Roads in Moreton Bay before 2359 that night.

Figure above: Section of navigational chart Aus 236 showing Qian Chi’s anchor position.

12 January 2011, 1200 hours. Cargo operations on board Qian Chi were stopped.

12 January 2011, 1300 hours. A harbour pilot boarded and the ship was moved to an anchorage in Moreton Bay.

12 January 2011, 1600 hours. Qian Chi was anchored and the pilot had disembarked. The final anchorage position was about 4 miles from the entrance beacons. Given the weather and the condition of the flooded Brisbane River, it was not known how long the ship would be at anchor. Consequently, the engineering department continued watchkeeping duties and undertook routine and general engine room and machinery maintenance. During the initial days at anchor, all necessary machinery systems, including the thermal oil heaters, were operating normally.

14 January 2011, 2120 hours. The ship’s number two thermal oil heater failed to fire. The unit was stopped and the burner lance removed and the igniter electrodes cleaned. It was then put back into operation and observed to operate correctly through four on-off cycles. It was then left operating overnight.

14 January 2011, morning hours. Further ignition failures occurred. The engineers attempted to remedy the situation by cleaning and adjusting the ignition electrodes. However, they had no success and, by mid-afternoon, the decision was taken to leave the unit off for the evening.

16 January, morning hours. The engineering staff met and discussed the day’s work schedule. Effort was again to be directed toward getting the number two thermal oil heater operational. With the exception of the fourth engineer, all engineers were variously engaged in this work. After further checking of the ignition electrodes, the heater ran for about 90 minutes, cycling eight times without incident.

16 January, 1050 hours. The heater failed again to ignite. Rather than continue working on the unit, the engineers went to lunch.

16 January, 1400 hours. The electrician began inspections of the thermal oil heater electrical systems. This included verifying the igniter circuitry and checking and setting the electrode condition and position. At about this time, the third engineer and the cadet began inspecting and cleaning the burner lance and nozzle. They removed the nozzle from the burner lance and took it to the workshop for further inspection and cleaning. The third engineer dismantled the nozzle and found it to be clean and in good condition. He then reassembled the nozzle. At this time, the chief engineer came into the workshop and confirmed the condition of the nozzle and reaffirmed the conduct of the work. The nozzle was then refitted to the burner lance and the burner reassembled.

16 January, 1500 hours. The thermal oil heater burner had been reassembled and prepared for operation. The engineers then initiated the burner’s automatic start sequence. The third engineer was crouched on the deck grating above the thermal heater to observe the operation of the burner unit, fuel regulator and linkages. From there, he was able to look through the observation port in the burner top while waiting for ignition and firing. The cadet was standing just forward of the burner unit, on the same level as the third engineer, observing the burner fuel pressure gauge. The electrician was a little further away, to port, having just returned to the area to observe ignition. At the time, everything appeared to be operating as normal, with the forced-draught fan and fuel supply pump running as the heater went through its 4 minute purge cycle. The third engineer observed and confirmed the operation of the fuel regulator as it opened and closed–in the fuel flow as the system sequenced. After some time, the third engineer refocused his attention to the peep hole to observe the ignition.

16 January, 1512 hours. The burner igniter operated and the thermal oil heater exploded. The explosion lifted the thermal oil heater casing top (see photo below). Several securing bolts were snapped as the force of the explosion was released into the upper engine room, the funnel space and out the open access door onto deck.

Photo above: Thermal heater top damage – including lifted top plate, bent steel and piping and damage to fixtures and lagging.

Photo above: Thermal oil heater top showing burner and fuel supply layout.

The burner arrangement was pushed out of alignment and the air duct inspection cover fitted to the burner was torn from its four securing bolts. The deck grating and mounting supports were upset about 300 mm vertically. The ducting from the externally mounted forced-draught fan was torn apart at the canvas flexible joint. Fuel lines running across the top of the thermal heater were deformed, and at least one began to leak from a weakened flange.

The explosion triggered the engine room fire detection system initiating a fire alarm on the fire control panel on the ship’s bridge. At the same time, the local fire suppression system automatically activated and doused the area around the top of the thermal oil heater with a fine water mist. This also initiated water mist release alarms in the machinery space adjacent to the oil heaters, in the machinery control room and on the bridge water mist alarm panel, but not throughout the remainder of the ship.

The force of the explosion threw the third engineer to the deck. The flame-front escaping from the thermal heater engulfed the area around the top of the unit and with it, the three crew members. All suffered burns, to varying degrees, over large portions of their bodies. They were blackened all over, their hair and exposed skin was burned and their clothing dry, brittle and coming apart. The third engineer was more seriously injured than the electrician and cadet with severe burns to his arms and hands. However, none of the men were incapacitated and they were able to make good their escape from the area.

The electrician and the cadet made their way onto the open deck and forward to the accommodation where they met the chief mate, who told them to go to the political officer’s cabin for medical treatment (see figure below). The third engineer escaped down into the engine room and made his way toward the workshop where he met the chief engineer who had heard the explosion and was making his way aft to investigate. He directed the third engineer to the political officer’s cabin to seek medical assistance.

Figure above: Qian Chi arrangement showing general location of explosion, workshop, cargo control room, machinery control room and master’s cabin.

The chief engineer, along with an oiler, proceeded to the thermal oil heater space. In the vicinity of the heater top, they found smoking debris and liquid. Using a handheld fire extinguisher, they extinguished a small localised fire. The chief engineer then directed that the fuel supply pump to the thermal oil heaters be stopped.

The explosion was heard throughout the ship’s accommodation. Both the master and the political officer immediately went to the bridge to assess the situation. Upon arrival, they saw that the fire control panel was alarming and that a large quantity of black smoke and soot was coming from the funnel.

The chief mate went to the cargo control room to investigate and secure the cargo system. He saw that everything was in order and then called the bridge and verified that the officer of the watch was aware of the situation and to ensure the general alarm would be sounded to muster all of the crew. He then returned to the deck to muster the crew.

The master called the engine room and was informed that number two thermal oil heater had exploded.

16 January, 1514 hours. The master activated the ship’s general alarm to muster all personnel in response to the emergency.

The crew mustered and were organised to inspect and assess the area around the number two thermal oil heater. The chief mate assembled a fire fighting team and they entered the space from the main deck. The chief engineer confirmed that any fires had been extinguished and the fire team was then tasked with securing and monitoring the area. The oiler was tasked with securing the fuel line and any other flanges loosened during the incident and to ensure that there was no further fuel leakage.

Once satisfied with the local conditions and response, the chief engineer went to the bridge to discuss the situation with the master. The chief mate went to the political officer’s cabin to lend assistance to the injured crew members.

The three injured men were seated in the political officer’s cabin. They had their burned clothing removed and all were given pain killers to assist with the pain. Their exposed skin was covered with clean dry cloths and, other than being given water to drink, little other treatment was administered.

16 January, 1539 hours. The master contacted Brisbane VTS by VHF radio, reported the incident and requested medical assistance. The master also contacted the ship’s local agent and the company’s Australian representative, informing them of the incident. The VTS unsuccessfully attempted to call the Queensland water police for assistance. They then contacted the Queensland Police communications centre and were advised to telephone the emergency ‘000’ number directly.

16 January, 1542 hours. VTS called ‘000’ and were directed to Ambulance emergency at the Queensland Ambulance Service (QAS). VTS informed them of the situation and  explained the ship’s location. They also explained the need to assemble at the water police base at the port for transport by boat to the ship. The emergency operator dispatched QAS paramedics immediately. The operator also passed on the emergency information to other agencies.

16 January, 1546 hours. The Queensland Fire and Rescue Service (QFRS) were notified of the incident. They responded with two vehicles to the water police base.

16 January, 1548 hours. Qian Chi’s master contacted VTS to request a helicopter evacuation of the injured men as they were seriously burned and in great pain. He told VTS that the ship had no helicopter landing area and that the injured men would need to be winched off the ship.

16 January, 1550 hours. VTS contacted the water police and requested assistance in organising the helicopter evacuations. During subsequent conversations, it was mentioned that the ship was a products tanker and would ‘have gas everywhere; venting’.

16 January, 1600 hours. Qian Chi’s chief mate contacted the Shanghai Seamen’s Hospital and requested assistance and guidance regarding medical treatment for the three crew members. In addition to gaining urgent shore assistance, he was advised to puncture what blisters he could with a needle to release the accumulating fluid.

16 January, 1609 hours. The water police informed VTS that the helicopter option was not available and that they would consider the ship to have a 500 m exclusion zone around it because of its condition.

16 January, 1610 hours. VTS informed Qian Chi that the ship’s earlier request for a helicopter evacuation was denied and assistance, in the form of paramedics and fire officers, would be arriving in about 30 minutes by launch. In anticipation of the arrival of the shore medical personnel, the three injured men were moved from the political officer’s cabin down to the cargo control room. The QFRS and QAS teams had gathered at the water police base. Two police launches had been organised.

16 January, 1617 hours. The police launches departed. Five QAS personnel were on board the first launch and two QFRS personnel on the second. When the paramedics arrived at the ship, they made their way to the cargo control room and assessed the condition of the injured men. Pain medication, including morphine, and oxygen were given to all three as needed. The paramedics quickly determined that, given the patients’ condition, helicopter evacuation was required as transport by launch would be impractical.

16 January, 1652 hours. The request for two helicopters was made.

16 January, 1708 hours. The second police launch arrived at Qian Chi and two QFRS fire fighters boarded to assess the ship for possible dangers and risks.

16 January, 1735 hours. The first helicopter arrived overhead Qian Chi. The electrician and cadet were assisted down to the main deck and were winched to the helicopter and transported directly to the Royal Brisbane Hospital. Soon after, the third engineer was winched on board the second helicopter in a stretcher. This helicopter had a doctor and extensive facilities on board.

16 January, 1811 hours. The helicopters and the fire officers had departed the ship.

16 January, 1815 hours. The paramedics departed.

Qian Chi remained at anchor until the morning of 19 January, when it berthed to complete cargo discharge. On 20 January, the ship was moved to another berth so that further inspections and temporary repairs could be carried out. On 21 January, Qian Chi departed Brisbane bound for Daesan, South Korea, where permanent repairs were to be made.

Root causes

According to the investigation report by ATSB, the following have been identified as root causes of the accident:

• The burner nozzle had been incorrectly assembled after maintenance. As a result, the valve stem was bent (see photos below) and, consequently, the needle valve failed to seal the burner nozzle. This led to fuel leakage through the nozzle and into the heater furnace.
• Throughout the 4 minute pre-ignition cycle, with the fuel pump and forced-draught fan running, the leaking fuel combined with the air to form a combustible atmosphere in the furnace. The explosion occurred at the completion of the pre-ignition cycle when the igniter activated.
• The design of the burner nozzle allowed the nozzle swirl plate and needle valve to be misaligned (see photos above) when being assembled which in turn led to the needle valve stem being damaged during assembly. Furthermore, the maintenance manuals and supporting documentation supplied by Garioni Naval, the thermal oil heater manufacturer, did not provide sufficient guidance to ensure safe and appropriate maintenance of the thermal oil heater burner assembly.
• The thermal oil heater was firing on marine gas oil, but the pre-ignition cycle time had not been reduced in line with that suggested by the manufacturer. Had the pre-ignition cycle time been reduced, there would have been significantly less fuel in the furnace and the explosion would probably have been less severe.

Figure above: Garioni Naval vertical thermal oil heater as fitted in Qian Chi.

Figure above: Burner nozzle showing open and closed positions.

In addition to the above the investigation highlighted also the following:

• Qian Chi’s crew received first aid advice and provided first aid to the injured crewmembers that was inconsistent with accepted and published first aid advice for the treatment of burns on board ship.
• Initial Brisbane VTS actions when contacting emergency services did not follow existing port procedures. When attempting to provide assistance and appropriate expert advice to the emergency services, VTS actions were hampered by a lack of, and confusion with, relevant information and processes.
• Brisbane port authorities had not put in place sufficient procedures, checklists and/or supporting documents to ensure VTS staff were adequately prepared, trained and practiced to handle a predictable incident such as this.

Lessons to be learned

• Ship’s crews need to understand the importance of applying immediate first aid to injured persons while seeking further treatment advice. This is particularly relevant for burn injuries; the accepted practice for which is cooling of the injury for an extended period of time, regardless of the extent of the injury.
• Equipment manuals should highlight the importance of correct burner nozzle assembly and alignment of its component parts.
• Increased awareness of the risks associated with the maintenance of burner nozzle should reduce the likelihood of future similar incidents.
• Port authorities should have in place sufficient procedures, checklists and/or supporting documents to ensure VTS staff is adequately prepared, trained and practiced to handle a predictable incident such as this.

Source: Australian Transport Safety Bureau (ATSB)