Although not yet included in Shark ESMS all Asphalt plants are required to be assessed, will have Hazardous Area zones and Hazardous Area equipment which requires routine maintainance inspections over and above non hazardous area inspections..
More detailed informationon regarding hazardous areas can be found at Hazardex.com both generally and specifically for Asphalt plant and Bitumen Silos.
A Hazardous area should be conducted for the site the steps2 are:
Based on the DSEAR assessment findings it is the sites responsibility to:-
After the DSEAR assessment is complete the equipment in the zone needs to be assessed as compliant with the protection level and type suitable for the zone.
Non compliant equipment must be replaced or moved outside the marked zone.
The flashpoint of Bitumen is >=230°C and therefore is not considered under the Hazardous area regulations which only apply to materials with a flashpoint of <=60 °C. This has known to be overlooked in some misinformed DSEAR reports. Unfortunately, if that report is accepted there are potential consequences if it is not implemented with the 'erroneous' zoning being treated as any other hazardous zone with gas group5 and T rating specified.
Vapour can be released Bitumen stored in a Silo when heated even though it below the flashpoint temperature. This vapour is not Bitumen, simple monitoring and research suggests it is primarily Carbon Monoxide (CO) with Hydrogen Sulphide (H2S), bitumen particulate and possibly other gases.
It has been reported that traces of Hydrogen could present, this could cause issues with the equipment certification so it is critical the vapour is correctly identified.
As well as in the silo headspace the gas is expelled from the exhaust pipe, which becomes a source for a Hazardous Area zone. It is extremely unlikely that general leakage of Bitumen from flanges etc would generate enough vapour to create an explosive mix however, under certain circumstances,the bitumen could be a fire hazard6 Zoning the area and using Hazardosu area certified equipment does not neccesarily solve this issue.
Carbon Monoxide is classed as gas group IIB by EN 60079-20 and therefore IIA equipment would be unsafe. Of more serious consideration is both CO and H2S re highly toxic many orders of magnitude below the LEL which is a greater hazard for personnel.
Prior to 2015 the flashpoint cutoff was 55°C excluding Diesel (flashpoint 55-60°C) from the scope of EU ATEX directive (now replaced by the UKEX regulations). This was then raised to 60°C so all diesel storage tanks installed after June 2015 must comply with the hazardous area standards.
However, the government guidelines are pragmatic regarding the change in status for Diesel. If the equipment was installed prior to 2015 then a risk assessment can be applied. it is not mandatory to replace with equipment certified to EN 60079.
In simple terms if the equipment was specifically designed and supplied for Diesel use prior to 2015 use the risk is minimal and it can be continued to be used with an appropriate risk assessment.
Other equipment within the zone must be suitably certified.
As Diesel is such a low risk the zone, even within the bund the zone can be limited, even negligible. Certainly, if good housekeeping is in place, then routine drips from nozzle and filling point or flanges are generally accepted to be unlikely to create an explosive atmosphere. Each storage tank must be assessed individually.
This can be Mains Gas, LPG or Kerosene. The pipework, pumps and storage (if any) all should be assessed as they represent very real explosion risks. All tanks and electrical equipment must be compliant , particularly if in an enclosed space where pumps and all associated equipment must be suitably certified with Earth bonding for metal storage tanks.
Area where solvents or flammable gases are stored will need to be assessed.
This can include cages for gas bottles or cabins storing solvents.
Non flammable substances such as oils, lubricant, adblue & water based paints do not need to be considered, generally oil based paints are unlikely to be a source of sufficient flammable vapours to create an explosicve atmosphere.
Low volumes of solvents in containers may not be a sufficient source unless decanting is being done in a confined space.
The zone evaluation is based on the volume that an explosive mix could occur, not just because the material is present.
When the DSEAR Hazardous area report is implemented all measure should be put in place for that site forthwith, or at least a credible short term plan for addressing the issues. Failure to comply can be subject to large fines for the company and potentially the site responsible person with minimal legal action.
Once the Zones with associated Gas groups and Temperature rating is established a survey should be done for compliance requirements covering
Electrical equipment
All cables within the zone – even if connected to equipment outside the zone.
Moving Mechanical components. – e.g. motor gearbox, fans, pumps etc
For further information please contact us
Notes
With the exception of Northern Ireland where the 'Northern Ireland Protocol' makes the European Directives valid ↩
For gas only, Dust assements are slighting different but the principles are the same ↩
The terms Gas and Vapour are interchangeable.
As are Lower Explosive limit (LEL) and lower flammable Limit (LFL) ↩
Excluding dust. ↩
Bitumen does not have a gas group so it is difficult to see how it can be specified. ↩
The ignition temperature of Bitumen can fall as low as 100°C when it mixes with insulation.
This is a flammability rather than an explosive issue. ↩