|Offender||Oilfield Transport Services Pty Ltd (ACN 130 726 475)|
|Charge||Charge Number||Offence Date||Date Convicted||Regulation||Section||Penalty Provision||Penalty Imposed||Date Sentenced|
|1||BM9/12||1 December 2008||15th May 2012||19(1) 19A(2)||3A(2)(b)(i)||$60,000.00 (Global)||15th May 2012|
|2||BM10/12||1 December 2008||15th May 2012||21(2)(b)(ii) 21A(2)||3A(3)(b)(i)||$60,000.00 (Global)||15th May 2012|
|Description of Breach(es)||
Charge 1 - Being an employer, the accused did not, so far as was practicable, provide and maintain a working environment in which its employee was not exposed to hazards, and by that contravention caused the death of Geoffrey Lucas.
Charge 2 - Being an employer failed, so far as was practicable, to ensure that the safety or health of a person not being its employee, was not adversely affected wholly or in part as a result of any hazard that arose from or was increased by the system of work that has been or was being operated by the accused, and by that contravention caused the death of Leon Mobbs.
The Accused is a transport services company that operates in the oil and gas industry in the north west of Western Australia.
The Accused was engaged by Baker Hughes Australia Pty Ltd ("Baker Hughes") to collect barite powder from the Baker Hughes depot at 11 De Castilla Street, Broome ("the Baker Hughes Broome depot") and deliver it via the Accused's road tankers to the Broome wharf to be transferred on to ships which then deliver it to drilling rigs/platforms off shore. This was the extent of the Accused's work.
At the Baker Hughes Broome depot were two silos, used for the storage of barite. Barite is a fine white powder with a high density derived from limestone. The most common use for barite is as a weighing agent in the offshore drilling process. Transferring barite was done via pressurised air, which was used to carry the barite through pipelines as when barite is dry it has a natural tendency to flow. A road tanker would often park in between a covered area and the entry gates at the Baker Hughes Broome depot, with the rear of the tanker close to the covered area. Hoses were then run from the silos to the tanker for the purpose of loading barite.
This method was used to transfer the barite into the silos, from the silos to road tankers and from the road tankers into the vessels taking it off shore. Air to pressurise the pipeline was supplied by a mobile compressor, which was owned by the Baker Hughes. Dry air from the compressor entered the tanker inlet manifold through a pressure safety valve and one-way valve. The amount of air used was controlled by the person operating a regulator on the compressor. The air then entered the aerators at the bottom of the tanker, thereby building up pressure within the tanker which contained the barite. The air escaped the tanker via discharge lines, carrying the powder with it, to the item the tanker as connected to. This would be the vessel, supply ship or silo.
The accident - 1 December 2008
The road tankers provided by the Accused for the task of collection and delivery of the barite on 1 December 2008 were a white 3 axle trailer / semi trailer WA registration BM12328 ("the white tanker") driven by the Accused's employee and a yellow coloured 3 axle trailer / semi trailer WA registration BM12256 ("the yellow tanker") driven by another of the Accused's employees.
On 1 December 2008, the road tankers collected the barite at the Baker Hughes Broome depot and delivered it to the Broome wharf where the barite was to be transferred on to a supply vessel.
The weather conditions in Broome that day listed by the Australian Government Bureau of Meteorology were temperatures ranging from 26.8 degrees to 31.6 degrees with nil rain and the relative humidity was recorded as 72% at 9am and 64% at 3pm.
The transfer of the barite to the supply vessel was not completed at the wharf that morning as the barite contained too much moisture, causing it to cake or clog inside the tanker. This did not allow the barite to flow freely. The excessive moisture content may have been caused or contributed to, by initial moisture when the barite was delivered, whilst within the silos, the humidity on the day, or an inefficient water/oil trap on the mobile compressor.
Different methods were used in attempts to remove the barite from the road tankers, including driving the tankers around the wharf to shake the powder down, banging on the hoses and sides of the tankers with a rubber mallet and increasing the air pressure into the road tankers.
A worker, who worked for Baker Hughes as the manager of the Baker Hughes Broome depot, was at the wharf with the tanker drivers on 1 December 2008. The worker was heard to have a conversation with one of the Accused's two tanker drivers, in relation to increasing the pressure within the tanker. The worker was increasing the pressure within the tankers by increasing the opening of the mobile compressor valve. One of the tanker drivers told the worker to keep the pressure down below a certain level. The worker insisted on increasing the pressure. The Accused had told the tanker driver not to operate the tanker. He was only to drive the tanker.
Despite the efforts of the worker and the two tanker drivers, the bulk of the barite powder was not emptied from the tankers. A decision was made by the worker to return to the Baker Hughes Broome depot and empty the pressure tankers back into the silos.
Both road tankers then returned to the Baker Hughes Broome depot where attempts were made to transfer the barite from the road tankers back into the silos. The unloading of the yellow tanker commenced.
Again the tanker driver and the worker had a conversation during which the tanker driver told the worker to reduce the pressure. The worker told the tanker driver that because the tanker was getting blocked and he would have to keep that pressure up.
The unloading of the yellow tanker was finally completed at approximately 2.45pm.
The white tanker was then connected to the mobile compressor and its unloading commenced.
At various stages, the powder tanker was depressurised and two labour hire workers were sent inside the tanks in efforts to scrape down and break free the caked barite.
This method of depressurising and repressurising was repeated a number of times. On the final occasion that the worker repressurised the white tanker, the tanker failed to maintain its integrity and ruptured. The explosion caused fatal injuries to the worker and the tanker driver who were standing alongside the white tanker.
Over-pressurisation of the white tanker
There were two pressure gauges on the white tanker. One gauge gave a reading of the manifold inlet pressure, although it had not been sufficiently maintained to be considered reliable. The second gauge, which measured the pressure inside the tanker itself, did work. A variety of tests conducted after the incident indicated that the tanker was subjected to over-pressurisation.
The worker had continually increased the pressure from the mobile compressor into the tanker, both at the wharf and back at the Baker Hughes Broome depot. He did not have information available to him in relation to the white tanker's maximum safe operating pressure. Such information could usually have been obtained from the owner of the tanker or from the data plate on the tanker. However, the Accused was not aware of the correct maximum safe working pressure of the white tanker or the location of the data plate, which was illegible in any case.
The maximum safe operating pressure of the white tanker was well below that of a modern tanker.
The white tanker's data plate contained very important information, such as its capacity and operating pressure. The correct operating pressure of 14psi (96kPa) was stamped on the data plate. The data plate was difficult to locate (it was on top of the tanker) and totally illegible due to its age, condition and wear. Extensive treatment was required to be able to interpret the information on the data plate. There was no information or direction provided by the Accused guiding the worker to the data plate.
The white tanker was not registered with WorkSafe WA or any other Authority, which is a requirement under regulation 4.14(1) of the Occupational Safety and Health Regulations 1996. The tanker was purchased by the Accused from a seller in Victoria approximately 14 months prior to the incident and was not supplied with any documentation such as an operator's manual. Although regulation 4.43(1) of the Occupational Safety and Health Regulations 1996 required the white tanker to be operated, maintained and inspected in accordance with AS/NZS 3788, there was no inspection of this tanker carried out by a competent person on purchase, or since purchase. The only record of any testing was the date of repair and hydrostatic test in 1986 which was recorded on the data plate on top of the tanker.
The white tanker was examined by an expert Metallurgist, on 19 March 2009, who found the tanker had been significantly modified and repaired prior to the accident. He found that the quality of these repairs had compromised the integrity of the pressure vessel, and that welding repairs made to the tanker would not pass design criteria or testing and they had been performed without the use of weld procedures or with qualified personnel. The metallurgical testing also found that modifications made to the baffle plate between the two compartments of the vessel caused a loss of rigidity, which contributed to fatigue, which in turn would have been sufficient to manifest a failure.
The failure of the white tanker started at the triple point between the two compartments, and pre existing fatigue cracks were the initiation point. The rupture was due to rapid crack growth as a result of a build up of pressure. These fatigue cracks were the result of inadequate repairs.
The Pressure Safety Valve
The tanker was fitted with a pressure safety valve ("PSV") Rapid model 228, at the beginning of the intake lines. The purpose of this safety valve was to open when the tanker pressure reached a set maximum. On examination of the PSV after the incident, it appeared to be in a normal operating condition although it contained water and compressor lubricating oil that was determined to have originated from the mobile compressor which had an inefficient water/oil trap.
Later inspection revealed that the PSV was missing a valve cap, had no form of tamper proof sealing, the set pressure adjusting screw was at its maximum setting, it was not sitting correctly and the lock nut was missing. It also had no serial number, set pressure or model markings. The valve seat was also found to be damaged.
Tests found that the PSV opened at 230kPa (33psi). This was too high. It was the maximum possible setting. It should have opened at 14psi (96kPa), being the correct operating pressure as shown on the data plate.
Lack of Training
The Accused had no system of training employees in the limits and correct working pressures of the tankers.
The Accused entered a guilty plea to both charges and was convicted.
|Court||Magistrates Court of Western Australia - Broome|
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