47801121223 - RBI Methodology - Risk Based Inspection

RBI Methodology for Risk Based Inspection

1. Donegani Anticorrosione S.r.l 1
RBI Methodology
API 580 – 581
Risk Based Inspection

2. Donegani Anticorrosione S.r.l 2
Introduction
Although the term ‘RBI’ has been adopted relatively recently,
the practice of planning plant inspection based on the risk of
failure is not new. Most operators base the scope and depth
of their inspection plans on the rate of in-service damage
and the consequence of failure, within a traditional time-
based inspection programme. (Same operators can rightly
claim that their plant inspections have always been risk-
based).
The term ‘RBI’ refers to a structured, team-based
assessment process with the aim of targeting inspection by
considering the Risk of Failure (RoF), which is a combination
of the Likelihood of Failure (LoF) and Consequence of
Failure (CoF).

3. Donegani Anticorrosione S.r.l 3
RBI – Risk Based Inspection
•Is based on the norms API 581 & RP 580
•Developed by API (American Petroleum
Institute) in collaboration with:
- DOW
- SHELL
- FINA
- TEXACO
- EXXON
- ………….

4. Donegani Anticorrosione S.r.l 4
Objective of RBI Methodology
•Increase safety
•Increase the productivity of inspection
•Decrease the losses of production
•Reduce the direct costs of inspection
•Change the frequencies of inspections
in base to the risk
•Prevent catastrophic damages

5. Donegani Anticorrosione S.r.l 5
RISK
Definition of the Risk:
Risk (RoF)
=
Likelihood of Failure (LoF)
x
Consequence of Failure (CoF)

6. Donegani Anticorrosione S.r.l 6
Risk Based Inspection
Consent of:
•Define the critical state for every single ITEM
•Create a priority for the Inspections basing
on the critical state
•Focus the attention on the expected
damages

7. Donegani Anticorrosione S.r.l 7
RBI Methodology
RBI Methodology developed by different
companies, varied in the details, but it is
founded however on fundamental step:

• Background to RBI
• Assessment Personnel
• Damage Mechanism Assessment
• Risk Assessment
• Inspection Planning and Risk Mitigation
• Updating RBI Assessment

8. Donegani Anticorrosione S.r.l 8
RBI Methodology
Step 1.
Background to RBI
Step 2.
Assessment Personnel
Step 3.
Damage Mechanism
Assessment
Step 4.1.
Likelihood of failure-LoF
Step 4.2.
Consequence of failure-
CoF
Step 5.
Inspection Planning
Step 6.
Updating RBI Assessment
Step 4.3
Risk Assessment

9. Donegani Anticorrosione S.r.l 9
Background to RBI
RBI study is designed around the systematic,
inductive assessment process of identifying historical,
active or potential damage mechanism in each
equipment. The process is a ‘bottom up’ procedure
where one damage mechanism id considered at a
time. Once the feasible damage mechanisms have
been identified, their probabilities (likelihood) of
leading to component failure are determined and their
effects on the components are recorder and analysed
to yield a calculated failure consequence.

10. Donegani Anticorrosione S.r.l 10
Assessment Personnel
All RBI systems have the following common
elements:
•Assessment preparation
•Information Gathering
•Damage Mechanism Review
•Risk Assessment
•Inspection Plans
•Inspection Review.

11. Donegani Anticorrosione S.r.l 11
Assessment preparation
Since RBI is a team-based approach, the
first step in the introduction of an RBI
programme is to identify and assemble a
competent Study Team. The RBI team
should include staff with knowledge of plant
operation, process hazards, risk assessment
and inspection techniques.

12. Donegani Anticorrosione S.r.l 12
Typical RBI team
•Inspection engineer(s);
•Material and corrosion engineer(s);
•Maintenance engineer(s);
•Process engineer(s);
•Operations engineer(s);
•Safety engineer(s);
•Team leader, typically a RBI
specialist(s).

13. Donegani Anticorrosione S.r.l 13
Information Gathering
Are necessary the following information:
• Operational manual
• P&ID
• Sketches of project of the equipment
• Pipe class
• Property of the fluids
• Design and operating conditions
• Special instructions and History inspection
• ……………

14. Donegani Anticorrosione S.r.l 14
Damage Mechanism Assessment
The Study Team will need to review the historical and
generic date relevant to each item of equipment. This will
include consideration of previous inspection reports (if
available) to determine the known or expected damage
mechanisms.
The review should consider damage mechanisms which
may lead to failure, their expected rates of deterioration and
the general location where damage may arise.
Wherever quantitative rates of damage are not available, an
element of expert judgement will need to be exercised by
the Study Team.

15. Donegani Anticorrosione S.r.l 15
Risk Assessment
The failure likelihood and the failure
consequence are calculated on the basis of
quantitative Likelihood Factors (LF) and
Consequence Factors (CF).

16. Donegani Anticorrosione S.r.l 16
Likelihood of Failure (LoF)
The answers to the LF questions are assigned a series of values
and associated weighting and the combination of all these
determines the Likelihood of Failure (LoF), derived for each
equipment in turn.
The LoF formula is specifically of the following form:
LoF = LF
2 Σ (LFi)
LF
2 = Failure likelihood (within a given period of time)
LFi = represents several factors that are considered to
contribute to the overall Likelihood of Failure.

17. Donegani Anticorrosione S.r.l 17
LF
i Factors
•LF
1: Current condition
•LF
2
:Failure likelihood
•LF
3:Inspection Effectiveness
•LF
4
:Shutdown Frequency
•LF
5:Operational Stability
•LF
6:Operation in Relation to Design
•LF
7:Recurring Repairs

18. Donegani Anticorrosione S.r.l 18
Consequence of Failure (CoF)
The answers to the Consequence Factors (CF)
questions are assigned a series of values and
associated weightings and the combination of these
results is the Consequence of Failure (CoF), derived
for each item in turn.
The CoF formula is specifically of the following form:
CoF = (FM x CF
1
x CF
2
) + (CF
3
x CF
6
) +
CF
4 + (CF
5 x CF
7) + CF
8 + CF
9

19. Donegani Anticorrosione S.r.l 19
FM Factor
In addition to other consequence factors the
consequence calculation also consider the
failure mode of an assigned damage
mechanism. Each damage mechanism
knowledge base is assigned one of three
failure modes, i.e. ‘Leakage’, ‘Leakage or
Rupture’, ‘Rupture’.

20. Donegani Anticorrosione S.r.l 20
CF
i
Factors
•CF
1:Product Loss
•CF
2:Pressure Factor
•CF
3:Explosion/Fire Damage Potential
•CF
4:Toxicity
•CF
5:Effect of Failure on Production
•CF
6:Location of Component
•CF
7:Time Taken to Rectify Failure
•CF
8:Threat Personnel/Environment
•CF
9:Engineered Safety Systems

21. Donegani Anticorrosione S.r.l 21
Weight of Factors

22. Donegani Anticorrosione S.r.l 22
Risk Matrix
The resultant Likelihood of Failure (LoF) is plotted on
the vertical axis, and the Consequence of Failure
(CoF) is plotted on the horizontal axis, as an
assessment point on a dimensionless five-by-five
Risk Plot. The Lof axis is grouped into five relative
Likelihood Categories, ranging from 1 to 5
(approximately 10-2/yr to 10-7/yr), and the CoF axis
is grouped into five relative Consequence Categories,
ranging from A to E. In this way, the Risk of Failure
(RoF) is considered to increase with increasing LoF
and CoF.

23. Donegani Anticorrosione S.r.l 23
Risk Matrix
L
ik
e
lih
o
o
d
1
2
3
4
5
B C D EA
Consequence
R
is k

24. Donegani Anticorrosione S.r.l 24
Inspection Planning
After the risk assessment, the Study Team develops
action plan based on all of expected damage
mechanisms. The inspection plane consider the
inspection interval and the scope of inspection.
The proposed inspection plane are designed to
provide an assurance that the ‘residual risk’ of the
equipment is in accordance with the ‘ALARP’
principle, i.e. the aim of assessing and managing
equipment is to reduce the RoF to As Low As is
Reasonably Practicable (‘ALARP’).

25. Donegani Anticorrosione S.r.l 25
Risk Mitigation
The RBI methodology systematically leads the
Study Team through the process of risk
mitigation, by considering several mitigation
action. The impact of each mitigation action
can be evaluated, for subsequent collective
appraisal of the benefits of the proposed
action, using the ALARP principle. An
appropriate strategy to manage the integrity of
each equipment is therefore developed.

26. Donegani Anticorrosione S.r.l 26
Updating RBI Assessment
RBI Study can be used to justify extending the periods
between inspections. The RBI process relies on a
feedback loop to update the inspection plan, such that
it is relevant to the actual condition of the plan. The
feedback stage provides continuing confidence that
damage dose not exceed expectations and ensures
that plan inspections take account of operational
experience.
Once an inspection plan has been developed during a
session, future inspection of the equipment should be
carried out to confirm that damage rates are within
expectations and to identify any unexpected damage.
The inspection should be carried out by competent staff
and the results recorded and re-evaluated.

27. Donegani Anticorrosione S.r.l 27
FeedBack of the Study
Start RBI
Inspection
Plan Rev.0
Plant
Operation
Shutdown/
Inspection
Inspection
Reporting
Inspection
Plan Rev.1
Maintenance
Shutdown
Plant
Operation
Maintenance
Shutdown
Base RBI
Assessments
Review RBI
Assessments

28. Donegani Anticorrosione S.r.l 28
Risk vs Time
No Inspection Plan
60 months
120 months
180 months

29. Donegani Anticorrosione S.r.l 29
Risk vs Time
With Inspection Plan
60 months
120 months
180 months

30. Donegani Anticorrosione S.r.l 30
DONEGANI ANTICORROSIONE SRL
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