Page 29 - Critical Control flipbook_Neat

Coal Mill Explosion

1 What is the name of the 2 What are its specific objectives related to the Priority Unwanted
critical control for Coal Mill
Event (PUE)?
Explosion?
Inertization Early detection of change in process parameters such as Temperature and CO level, and
automatically initiate the inertization sequence to prevent the formation of an explosive
atmosphere by having an inert atmosphere (either N2 or CO2) that could effectively
achieve a minimum of 2% below Limiting Oxygen Concentration. Provision of a manual
intertization from the Central Control Room (CCR) if a fire or smouldering detected by a
passerby

3 What are the critical 4 What are the activities 5 What can be sampled from
control performance
within the management
the set of activities for
requirements to meet the systems that support verification, providing a
objectives? having the critical control clear image of the critical
able to do what is required? control status?
Pre-defined Solenoid valve opening Safety philosophy and alarm setpoints Operators can manually initiate
position with a high-high level trip on are included in Standard Operating inertization by remote push button or
Temperature and CO Procedure (SOP) via CCR

Control system elements - Temperature Scheduled preventative maintenance Percentage of PM completion rate
transmitter, CO analyser, Solenoid valves and calibration in CMMS as per Number of defects found during
are periodically calibrated, along with a manufacturer’s requirements/ Corporate calibration and PMs. (This should be
suitable preventative maintenance (PM) CEM guidance documented in CMMS)
schedule and free of build-up or any Classified as highest priority and
obstruction critical equipment in Computerized
Maintenance Management System
(CMMS)

Periodic ‘end to end’ Trip testing Scheduled end to end trip testing in CMMS Completion rate of trip testing
(min once a year) Report deviation/failure as near-miss on Number of failed Trips upon testing
iCare

Instruments and equipment associated A systematic approach across the plant Number of non compliance to the
with inertization system are coloured or to identify, colour or tag as “critical” - This defined systematic approach
tagged as “Critical Control” in the field should be visual as well as identifiable in
CMMS

All manual isolation valves are locked Regular visual inspection of the area and Number of non compliance to the
open or the valve handles are removed installation defined systematic approach
at an open position

Inert medium (N2 or CO2) maintained full Regular (daily) tank inventory checks Percentage of PM completion rate
level in the tank/s Scheduled PMs for tank, pipes, valves, Number of deferred PMs
and gauges Number of defects found during
calibration and PMs. (This should be
documented on CMMS)

6 What is the target performance for critical 7 What is the critical control performance
trigger for shutdown, critical control review or
control?
investigation?

All the inspection, maintenance and testings are carried out Failed inertization upon testing
100% without any deferments. The inertization sequence is fully Unauthorised deferment without Plant Manager’s written
effective during tests authorisation

Creation date: 01/2021 • The latest and only controlled version of this document is available on the HSE intranet.
© 2021 Holcim - For internal use only