Expert observations of demolition dangers and how to avoid them
THE current economic climate and the uncertainty around a soft/hard Brexit have widely affected industry confidence across almost all business sectors with quite devastating results for some. The current UK cost base puts added pressure on industry with many choosing to either relocate outside of the UK, mothball to later restart (which very seldom happens) or full closure. Organisations are very proficient at managing and maintaining their assets and producing ‘product’, but now they find themselves going into the world of decommissioning and potentially demolition.
Demolition by name is a destructive process with many outside of the industry viewing most demolition contractors as low skilled. Headlines similar to those shown in Figure 1 are a far too common sight.
However, demolition is a highly specialist area of engineering requiring unique skills built up over many years. Most clients only ever do this type of project once in their career – or twice if they are really unlucky.
Figure 1: News stories similar to those shown here are a far too common sight
Demolition is just construction in reverse?
This is one of the biggest misconceptions, and in reality nothing could be further from the truth.
- Typically new plant and equipment is used.
- There is confidence in construction; with today’s quality and supervision there should be no surprises in the future.
- Laydown area - most pieces of the ‘jigsaw puzzle’ will be in a laydown area ready for assembly.
- Status of isolation - equipment has never been energised, therefore there should be no stored energy.
- Insulation - asbestos has been banned in the UK since 1999. There are other insulation materials but specific types and location should be well documented.
- Residue on the product - I have never dismantled or demolished a ‘clean’ plant in over 35 years.
- Condition of plant and equipment is unknown.
- Others’ bad practice, with examples ranging from a 2,400 t steel works building, where the roof trusses were not bolted to the main building support columns, to a process column that when it was installed did not function as planned. The column was then turned 180º and the drawings were never updated to show the new arrangement.
- Vessel weights and lifting equipment – these cannot be trusted due to a number of reasons and can be used as a guide.
- Restricted access and space - most operating plants develop around the older assets which in turn will normally be the first to be removed.
- Insulation - there are over 3,000 recognised uses for asbestos-containing materials (ACMs); past methods of removal aren’t to today’s high standards and it is recognised as the “hidden killer”. There are also risks associated with HCFC/CFC blown foam backed sheeting, and refractory/cristobalite, to mention a few.
- Isolations of plant and equipment, stored energy, unpicking a plant’s history from original design to modifications – both legal and illegal – is always underestimated.
In construction you have lots of knowns. When it comes to decommissioning/demolition there are potentially lots of unknowns. The objective during the planning process is to go from this potential unknown state to a known state.