The Risk Management Tool Box Blog

Pyrolosis in Truck Tyres

Graham Marshall - Friday, July 19, 2013

Coming into contact with overhead power lines when driving can cause the tyres on trucks, cranes and other heavy vehicles to catch fire and explode.

Five workers have been killed by exploding tyres in Australia in recent years and many more injured as excessive heat developing in tyres has led to the unpredictable phenomenon known as pyrolysis.

Pyrolysis can occur when excess heat is applied to a tyre.

Often it is a result of electrical arcing and current flow when rubber tyred vehicles have been involved in high voltage electrical incidents.

The heat decomposes the rubber and other compounds used to manufacture the tyre, creating a ready fuel source.

The ratio of this fuel to the air used to inflate the tyres can then reach flammable or LEL (explosive) levels.

The explosive energy released during a tyre explosion can lead to serious injuries or fatalities and significant equipment damage.

Because of the amount of kinetic energy released, a danger area up to 300 metres away is typically required to be established.

Pyrolysis related explosions are unpredictable, sometimes happening immediately, sometimes up to 24 hours after the heat was applied to the tyres.

And the explosion can happen with no visible signs of a fire on the outside of the tyre before it explodes.

Besides electrical heat sources, other sources of heat that lead to pyrolysis in tyres include welding (e.g., on wheel rims), oxy/acetylene heating wheel nuts, overheating brakes and wheel motor fires.

Tyre explosions predominantly occur with split rim configurations, but can happen with all types of tyres.

Any pneumatic rubber tyred vehicle involved in an incident where an electrical fault results in discharges or arcing around or through the tyres should be considered a potential hazard.

Procedures to follow when there is a danger of a tyre explosion, such as when a rubber tyred vehicle has contacted overhead power lines include:

+ Parking the vehicle in an isolation zone, with a minimum 300 metre radius;

+ Removing everyone from the area, and not allowing anyone to re-enter the isolation zone for 24 hours; and

+ Alerting fire fighting services to the potential hazard.

It should be noted that if pneumatic tyres are filled with nitrogen instead of air, it reduces, if not eliminates the risk of pyrolyic tyre explosion.

Kinetic Energy in Crane Wire Rope

Graham Marshall - Tuesday, May 28, 2013

The safety alert (below) produced by the Marine Safety Forum highlights how the stored kinetic energy hazard within wire-rope used in slings and rigging should be understood before working on changing out such types of wire-rope.

The alert also highlights the need for: 1) Document Procedure for the task; 2)  JSA to be completed highlighting the kinetic energy hazard; and 3) No one to stand in "line of fire" when removing spooled wire-rope.

Dropped Objects on MODUs in WA

Graham Marshall - Tuesday, May 14, 2013

There has been a dramatic increase in dropped objects occurring offshore Western Australia in the first quarter of 2013. 

Nine dropped object notifications have been received by NOPSEMA so far this year. 

All of these dropped objects have occurred on mobile offshore drilling units (MODUs). 

As a comparison, one dropped object was reported on a single MODU for the same period in 2012 and a total of 13 for the entire year.

The weights and heights of the dropped objects ranged from a couple of kilo's to over 2 tons and from less than 1 metre to 43 metres. 

The ‘DROPS Calculator’ highlights that a mass of as little as 700 grams falling from a height of 15 metres could result in a fatality. 

Dropped objects have included drill pipe and casing, a spool of wire rope, a navigation light fitting, slip inserts, a hose bundle, an equipment handle and a camera located in the derrick. 

Three members of the workforce have recieved injuries as a result of three separate dropped object events. 

Two workers required a medical evacuation from the offshore facility, while another worker required first aid  treatment. 

In another case, a member of the workforce was standing only 2 metres from where a 28 kilogram object landed having dropped from a height of 19 metres. 

Analysis using the industry supported ‘DROPS Calculator’indicates that six of these dropped object events could have resulted in a fatality.

Analysis of the dropped object events in 2012 highlighted the predominant root causes as being: 

1. Poor design of equipment; 

2.  Work procedures not being followed correctly; 

3.  Wrong procedures used or no procedures used; 

4.  Dropped objects not anticipated and factored into the planning for the work; 

5.  Lack of training, lack of instruction, lack of understanding of the task; and 

6.  Preventive maintenance issues.

Operators and other duty holders need to take urgent action  to arrest this worrying trend.

The Risk Management Tool Box re-iterates the requirement for duty holders in offshore and onshore environments to ensure an appropriate balance of preventative and mitigative control measures are identified and implemented during lifting operations.

There is also a critical need to apply the hierarchy of controls to kinetic energy hazards which are present during lifting operations.

In particular, operators are reminded that the control mechanisms should focus on elimination, substitution and engineering controls before consideration of administrative controls and the use of PPE.

Warning on Dropped Objects

Graham Marshall - Wednesday, April 24, 2013

I've recieved a safety alert email today from NOPSEMA warning about the number of dropped objects being recorded in 2013.

NOPSEMA has identified a concerning increase in dropped object events since the beginning of 2013. 

Nine dropped object notifications have been received by the authority in the first quarter of 2013. 

All of these dropped object events have occurred on mobile offshore drilling units (MODUs). 

As a comparison, one dropped object was reported on MODUs for the same period in 2012 and a total of 13 for the entire year.

Overall, a total of 31 dropped object events were reported in 2012 from the following facility types: 

+  13 MODUs;

+  11 platforms;

+  Five floating production storage & offloading facilities; and 

+  Two pipelay/accommodation/construction vessels.

The current spate of dropped objects is a cause for concern and should be addressed by Operators revisiting their lifting procedures.

Dropped Pipe Bundle on Rig

Graham Marshall - Monday, April 22, 2013

This safety alert from Vermillion Energy and APPEA highlights how a bundle of 5-inch 19.5 lb/ft drill pipe tipped and was dropped onto the deck during a lifting operation.

This could have been a very nasty accident, so lessons need to be learned and disseminated across the marine drilling industry to avoid a repetition.

Dropped Valve Actuator

Graham Marshall - Sunday, April 07, 2013

This Woodside safety alert shows how a 200 kg valve actuator was able to fall a distance of 20 metres to the deck below the crane before falling over the side and into the ocean.

The safety alert highlights the need for good risk assessment prior to any lift, the development of an appropriate lift plan for the specific lift in question, and the need for any person directing the lift to be standing in a place of safety.

We would suggest that a lift such as this should also be covered under an appropriately written and specific procedure.

Danger from overhead falling objects

Graham Marshall - Tuesday, January 29, 2013

The danger of "working below" - in situations where items can fall from height and strike workers has again been highlighted by the prosection in the UK of Steel manufacturer Tata Steel and a specialist contractor.

A fine totalling £320,000 has been handed down for safety failings after a worker was killed by a falling metal bar in the steelworks at Redcar.

Kristian Norris from Middlesbrough was working for Vesuvius UK Limited at the time of the fatal incident on 12 April 2008.

He was hit on the head by a  metal bar that fell approximately 30 feet from overhead.

Teesside Crown Court heard today that an investigation by the UK Health and Safety Executive (UK HSE) found that adequate precautions were not in place to control the risk of falling objects.

This was a failing on the part of both Vesuvius, and Tata Steel UK Limited, which then owned Teesside Cast Products where work was being undertaken.

Tragically, both company's were aware of the safety problems but both allowed the unsafe work to continue.

Vesuvius UK Limited and Tata Steel UK Limited both pleaded guilty to breaching regulation 10(1), of the Work at Height Regulations 2005.

Vesuvius was fined £200,000 and ordered to pay costs of £24,020. Tata Steel UK Limited was fined £120,000 and ordered to pay costs of £24,020.

After sentencing, HSE Inspector Richard Bulmer, said:

"Kristian’s tragic death may have been prevented had Vesuvius UK Limited and Tata Steel UK Limited made simple and adequate provisions to protect employees working beneath work and lift platforms. The risks associated with work at height are well known, as are the necessary safeguards. Yet on this occasion the precautions taken to prevent people or objects from falling were wholly insufficient and sorely lacking."


Dropped Power Pole Incident Alert

Graham Marshall - Wednesday, January 16, 2013

The Safety Alert from APPEA which is shown below illustrates how a worker was lifting/erecting a "two-part" steel power pole when a joint in the pole separated causing the bottom section of the pole to slide into the pre-made hole and the top section (still attached to the crane) to swing down and hit the ground.

No personnel was injured.

Key learning for all such lifting operations include:

> Ensure manufacturer’s specifications are reviewed and followed for installation projects;

> Ensure exclusion zones are implemented and observed throughout lifting operations; and

> Verify certifications for lifting points on equipment or structures prior to lifting.

Exclusion Zones in Crane Operations

Graham Marshall - Sunday, December 23, 2012

This Safety Alert from APPEA highlights the need to enforce procedures for crane operations.

It shows, firstly, the need for exclusion zones, in terms of establishing an area around the "drop zone" of any potential object which could fall; and secondly, the need to ensure that no person is allowed to enter the exclusions zone. 


Always Inspect Rigging Prior to Crane Lifts

Graham Marshall - Wednesday, December 12, 2012

This safety alert from APPEA highlights how a drill rig engaged by Chevron in Australia was involved in an incident in which a bolt torque wrench weighing-in at 70 KG fell 14 metres through the rotary table to the transporter below.

The dropped-object incident occurred when an eye-bolt on the torque wrench was used as the primary lifting point during rigging-up of the item prior to lift.

The eye-bolt was previously damaged and was not adequately inspected prior to the lift.  It subsequently failed under load.  The rest of the safety alert is shown below.

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