There are many certainties in life, and one of those certainties is that accidents will happen. Whether they are caused by human error, system or product failures, accidents will always be around us.
This short overview features an explosion that happened at a storage facilities in the UK. It also demonstrates how Link-Seal (if installed) could have reduced the severity of the situation quite dramatically by containing the spread of highly flammable liquids, thus significantly reducing the risk of further damage to assets and more importantly, the risk of loss of life. In this case, there was no loss of human life and this could only be viewed as a miracle.
This overview is not simply to demonstrate in detail how our product works, but to evaluate the effectiveness of our product in real situations and how that adds value within these extremely hazardous areas.
Buncefield Storage Facility Hemel Hempstead, UK 11 December 2005
Buncefield Storage Facility is located just north of London and was run by Hertfordshire Oil Storage (HOSL) which was a joint venture between Total (UK) and Chevron. This site stored various products including petrol (gas), heating fuel and Jet A1 aviation fuel which served local airports such as London Heathrow and London Luton. Being an inland depot, there were three main underground pipelines that transported product from refineries around the UK to Buncefield.
On the morning of 11 December 2005 there was a huge explosion that was caused by a vapour leakage. This resulted in a huge fire which soon engulfed other tanks in the area.
As with any major incident, there was a thorough investigation and this highlighted many areas of weakness. One of which was the bund/dike walls which surrounded the tanks and were designed to contain any leakage of fuels as a result of any breach in the tank wall or overfilling of tanks etc.
Any storage facility will have these bund containment walls, have a look the next time you go to the airport or pass a tank farm. The containment walls can be constructed using earth or concrete, or indeed a combination of the two.
There are many networks of pipes carrying fuel to and from the tanks within the storage complex that need to penetrate through the bund/dike walls and there are many different ways that companies and contractors have sealed these pipes passing through the walls. Around the world, we can observe several different methods of sealing pipes passing through walls and chambers.
Pipes can be cast directly into the concrete wall with a puddle flange, but this anchors the pipe which is not ideal, especially if the pipe is connected to pumps or valves that cause vibration.
- Some pass-through sleeves which have been cast into the walls, and the gap is generally filled with a type of grout which over time will crack/shrink, allowing gaps to appear and this was the case at Buncefield.
- These gaps between the carrier pipe and the sleeve I/D allowed burning fuels to pour out of the bund/dike walls, spreading to other areas of the site creating further danger to the facilities and human life.
Pipes can also be mechanically sealed. For many years now, Projex Group has been offering in Australia a double Link-Seal assembly for bund wall pipe penetrations. These consist of a nitrile rubber Link-Seal® on the wet side of the bund wall and a Silicon model ‘T’ Link-Seal on the dry side which has a two-hour factory mutual fire rating.
This means that if there is a leak from the tank and the bund fills with fuel, the nitrile Link-Seal® assembly will contain the spill and will not need to be changed out as it is resistant to hydrocarbons. In the unfortunate event that the fuel catches fire, the silicon Link-Seal® will be in place to contain the burning fluid.
Link Seals create an instant 100 per cent hydrostatic seal for the annular space of pipes passing through walls, floors or ceilings. They are supplied as a belt with a series of interconnecting rubber links and bolts that when tightened form a seal. They are resistant to chemicals, oils, gas, water and fire (two hour rating: AS -1530.4 and AS 4072.1).
The Link-Seal assembly shown also has an ‘on face’ wall sleeve which accommodates a fire-resistant casing end seal that offers additional fire protection. Once energized, our offerings will maintain a permanent seal, and will also give the opportunity to be removed for inspection and reinstated.
If this system had been installed at the Buncefield terminal, the spread of fuel would have been halted and the damage would have been reduced dramatically. The final report from the HSE (Health & Safety Executive) shows some methods that are available for sealing pipes penetrating bund walls and the Link-Seal® system is shown as an option, although it is not referred to by the brand name of Link-Seal®, but by the generic term ‘modular seal’.