Standard EN 1127-1 distinguishes fourteen types of ignition source:
- hot surfaces
- flames and hot gases
- mechanically generated sparks
- electrical apparatus
- stray electrical currents, catrhodic corrosion protection
- static electricity
- electromagnetic fields in the frequency range from 9 kHz to 300 GHz
- electromagnetic radiation in the frquency range from 300 GHz to 3 x 106 GHz or
- wavelength range from 1000μm to 0.1 μm (optical spectrum)
- ionising radiation
- adiabatic compression, shock waves, gas flows
- chemical reactions.
In this case we can see that the cause of the explosion may have been welding
Two contractors were on site, measuring some walkways….
One decided to carry out some welding, without permission, causing a tank to explode.
The blast blew out all the windows at Salters Cartage, Mr Salter said.
A worker at a nearby business said the explosion shook her building. Part of an exploding fuel tank had landed in a nearby yard, she said.
“It shook our whole house, [I] thought the windows were going to shatter, freaked the sh** out of me,” Janelle Stubbington said.
Workers at neighbouring sites said they saw debris flying through the air and billowing black smoke.
The ATEX regulations are very specific about the above activities:
For every workplace, there should be available a sufficient number of workers, with the requisite experience and training, to perform the explosion protection tasks assigned to them.
In working environments where explosive atmospheres may arise in such quantities as to endanger the safety and health of workers, appropriate supervision during the presence of workers must be ensured, in accordance with the risk assessment, by the use of appropriate technical means.
If work liable to cause an explosion is to be carried out in or near a hazardous place, it must be authorised by the (a competent) person with responsibility for this function within the establishment. This also applies to activities which may interact with other work to cause hazards. A system of “permits to work” has proved useful in such cases. This may be implemented by means of a permit-to-work form which all concerned must receive and sign.
In previous news report on our website you will see reports of a welder using an empty fuel drum to use as a work bench, another cutting an old drum with an angle grinder without investigating the hazard within, decommissioning a cleaned out tank then sending in an operative to cut up the tank walls or pipes within the tank where solvent had leached inside, causing an explosive vapour during the hot work. Competence is not just about training but should be backed up with experience in the relevant industry where the community knowledge (history) builds up, to avoid such incidents.