- Stored material
- Cement or cementitious blend
- Distinguish
- Loose powder, compacted material and hardened deposits
- Relevant hazards
- Dust, falling material and wet-cement contact
- Separate issue
- Condition of outlets and conveying equipment
Cement type and deposit condition
Cement and cementitious blends can leave loose powder, compacted material or deposits hardened by moisture. Product history, water ingress and changes in discharge performance help explain the condition inside the silo.
An obstruction visible at the outlet may represent only part of the retained mass. Deposits higher in the vessel can detach when disturbed, so the affected area needs to be considered as a whole rather than treating the outlet in isolation.
Water and cement residues
Cement reacts with water and can set. HSE also identifies skin and eye hazards from wet cement. Wet cleaning should not therefore be assumed suitable simply because it is used for other vessel contents.
The method has to reflect the deposit condition, silo construction and how removed material will be collected. Any cleaning agent needs product-specific assessment; improvised chemical treatment is not appropriate.
Flow problems and mechanical faults
Retained cement can restrict discharge, but a valve, outlet, feeder or conveying fault may also be involved. Removing the deposit does not prove that the discharge equipment is mechanically sound or correct an underlying flow-design problem.
Suitable non-entry techniques can avoid internal access. Work around suspended or bridged material, and any entry into the silo, requires competent assessment, isolation and controls for falling material and confined-space hazards.
Condition after cleaning
After cleaning, it should be clear what deposits were removed, what hardened material remains and which areas could be inspected. Cleaning and equipment inspection are related tasks, but they answer different questions about readiness for return to use.