Works precautions in ATEX dust zones

Risks related with welding and cutting works to be considered in ATEX dust risk analysis, DSEAR

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Section summary
Risks related to fire and cutting works
How to handle fire and cutting works

Bulk Solids Handling Safety
# Dust explosion physical properties # MIT - Minimum Ignition Temperature of dust

1. Introduction

Industrial processes are constantly the object of maintenance or process modifications to improve its reliability and performance. Any work in ATEX area must be carried out with specific precautions as the presence of dust can create an explosive atmosphere whose ignition can come from the activities done on the process.

2. Risks related to welding and cutting

Welding and cutting are 2 of the most common activities involved in a process site for maintenance or upgrading a process. They are also an important source of ignition of dust clouds as welding implies very high temperature at the point of welding, and cutting creates a lot of sparks and heating.

If a dust cloud is initiated and enters in contact with a piece of metal being welded or cut, an explosion will occur. As well, if dust is lying on a part being welded or cut, or in the inside of that part, it will starts to burn and can trigger an explosion.

3. How to handle welding and cutting works

In general welding and cutting works MUST BE FORBIDDEN DURING PRODUCTION in ATEX areas.

Any such activity must be conditioned to a WORK PERMIT that must be granted by the responsibles of the production areas. It is out of question that mechanics just start to weld or cut in production area without permit. The permit will allow to carry out a risk analysis and authorize it only when the installation is safe.

Many accidents have happened in the past, especially in grain or flour silos, because contractors started to work in an unsafe environement. There must be a no tolerance policy on these aspects.

Prior to work the installation must be secured, especially stopped if the works is outside the process, and cleaned if there is any risk equipment are touched by the work. An inspection must be carried out prior to starting the works.

The risks related to fire works, like welding and cutting, must be described in the ATEX risk analysis and the measures to put in place explained. Conclusions of the risks analysis must be implemented by the factory.

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