Risk Assessment on Storage and Handling of Highly Toxic …
463
3.2.1 Occurence
Occurence rating is given based on past performance and failure rate, and generally,
it was scaled in 1–10 ranking, and this scale gives the probability of occurence in its
lifetime.
3.2.2 Severity
Severity rating is given based on seriousness of risk which could cause an accident
lead to permanent disablement or death. Generally, severity rated in scale 1–10, rank
1 indicates the high severity.
3.2.3 Detection
Detection rating is given based on how early detected before failure happens. If
detection is possible early before major failure, we can reduce no of accidents,
generally detection rated in scale 1–10, and here, rank 1 indicates easily detectable,
whereas rank 10 indicates the almost not detectable (Table 1).
Table 1 FMEA format for TDI handling system components
Item no.
Component
description
Failure mode
Effects
Safeguards
Actions
1
Ball valve
Plugged
Intended flow
not occurs
Periodic
maintenance
and testing
Prepare
checklist
Struck open
TDI spillage
due to
receiving bin
over flow
Periodic
maintenance
and testing
Prepare
checklist
2
Bin/Vessel
Rupture
TDI spillage
Hydrotesting
of vessel
Check due
date of testing
3
Hoses
Rupture
TDI spillage
Replacement
of hoses
Fix the
replacement
schedule
4
Flange joints Gasket failure
TDI spillage
Replacement
of gasket
Fix the
replacement
schedule
Fasteners loose
TDI spillage
Periodic
maintenance
Add checklist