1.0 Purpose
This Standard Maintenance Procedure (SMP) provides maintenance, safety and health instructions
during Boiler bunkers/ silos emptying and cleaning to protect the personnel and equipment.
2.0 Scope of application
This procedure applies to all activities associated with emptying, cleaning, inspection and repairs of
Boiler bunkers / silos.
3.0 Responsible person(s)
a) Head of Department - Mechanical maintenance
b) SHEQ Manager
All the personnel involved in carrying out and supervising the above activities are required to ensure
implementation of this procedure and may consult any other relevant documents indicated under
reference section below. In the event of any changes required in the SMP such changes may be
requested by the mechanical maintenance head of department who would take appropriate action with
approval from the Head-O&M/ Plant head and SHEQ Manager.
4.0 Safety hazards and precautions
4.1 Safety hazards
Safety hazards during maintenance of Boiler bunkers/ silos include:
a) Coal/ ash dust inhalation
b) Sharp edges
c) Hot work (welding, gas cutting, grinding etc.)
d) Working at height (ladder/ man cage )
e) Material lifting with chain block(s)/ hoist
f) Rotary Equipment
g) Confined space
4.2 Safety precautions
Before carrying out Boiler bunkers/ silos maintenance activities ensure that the following safety
precautions are observed:
a) Obtain safe work permit (SWP)
b) Conduct TBT
c) Ensure safety clearance is given for working at height, hot work, confined space entry etc.
d) Adhere to risk preventive measures.
4.3 Required Personal Protective Equipment (PPE)
The following is PPE to be used based on the maintenance type:

Safety helmet

Safety shoes

Hand Gloves

Goggles

Nose mask

Safety belt

Life line

Fall arrestor (if man cage used)
5.0 Maintenance
Bunkers/ Silos emptying and inspection will be carried based on site requirement to rectify the internal
defects, if found any during the plant operating condition and for inspection of internals like lining,
fluidizing equipment etc.
Maintenance practices for bunkers/ silos include the following.
 Internal inspection of lining, fire protection system, poking/ loosening points, fluidization system etc to
ensure the healthiness of system.
 Repairs and maintenance of internal lining, nozzle points of emptying pipe, loosening machine and
CO2 injection (applicable for coal bunkers only)
 Repairs and maintenance of fluidizing pads & air piping (applicable for ash silos)
6.0 Procedure for Bunker/ Silo Emptying and Internal inspection/ cleaning
 Drain the Coal/ Ash inside the bunkers/ silos through the emptying pipes/ unloading equipment to the
open trucks/ closed bulkers up to minimum levels by taking proper precautions to control the dust.
 The balance coal/ ash can are removed by taking the proper care with necessary arrangement for
men movement & material removal.
 Prepare the required working tools at site and inspect the same before use.
 Obtain SWP & ensure all safety precautions are clearly indicated.
 Coordinate with operation department.
 Ensure Coal/ Ash feeding to the bunker/ silo isolated in all aspects before workmen enter to the
respective bunker/ silo.
 Ensure that CO2 gas lines are isolated before carrying out the maintenance activities inside the Coal
bunker.
 Make proper arrangement for workmen entry to bunker/ silo.

Cover the openings inside the bunker/ silo, if the workmen are directly landing on coal/ ash for
emptying/ cleaning from bunker/ silo.

Ensure proper ventilation and illumination inside the bunker/ silo. If required provide an exhaust
fan OR keep switch ON the fan in dust extraction system.

Considering men safety point of view, Coal bunker internals inspection/ cleaning from inside shall
be carried during coal conveying OFF condition only.

Ensure no men and working tools/ equipment left inside the bunker/ silo before closing the bunker
top cover/ silo access door.

Maintain proper confined entry register and maintenance check list.
7.0 References:

Bunker/ Silo general arrangement drawings

Safety Work Permit (SWP) Practices

Risk Assessment Document