RISK ASSESSMENT AND RISKRISK ASSESSMENT AND RISK--BASED BASED INSPECTION FORINSPECTION FOR
PETROCHEMICAL UNIT:PETROCHEMICAL UNIT:A PRACTICAL APPLICATIONA PRACTICAL APPLICATIONSong-Chun Choi, Je-Chang Ha, Kyosik Park
October, 28, 2008
Mary Kay O’Connor Process Safety Center, 2008 International Symposium& World Conference on Safety of Oil & Gas Industry
Mary Kay O’Connor Process Safety Center, 2008 International Symposium& World Conference on Safety of Oil & Gas Industry
�� IntroductionIntroduction
ContentsContentsContents
�� Development of KGS-RBITM
program for petrochemical plant
Development of KGS-RBITM
program for petrochemical plant
�� Application of KGS-RBITM
program on the NCC System in Petrochemical Plant
Application of KGS-RBITM
program on the NCC System in Petrochemical Plant
�� Results and DiscussionResults and Discussion
�� ConclusionConclusion
�� What is RBI
(Risk-Based Inspection)?What is RBI
(Risk-Based Inspection)?
�. Introduction (1)�. Introduction (1)
• Many refinery and petrochemical plants are being operated in Korea.
• Due to improvements of industrial technologies, the relevant equipment are
getting complex to allow operation in higher temperature and pressure
conditions.
• Thus continuous operation while sustaining their integrity through good mainte
nance practices becomes an important issue.
0
50
100
150
200
Previous of 1979 1980-1989 1989-2003
The number of petrochemical plants in KoreaThe examples of petrochemical facilities
�. Introduction (2)�. Introduction (2)
• The possibilities of accidents owing to aging equipment have increased in
refinery and petrochemical industries.
• Unanticipated accidents may cause significant social and economic losses.
• To reduce the possibility of such incidents, maintenance activities such as
inspection, repair or replacement of aging equipment has to be carried out.
• Thus, a risk-based inspection (RBI) methodology for refinery and petrochemical
plants should be established.
Unknown18%
Process Upset8%
Natural Hazard6%
Design Error4% Sabotage/Aroson
3%
Operating Error20% Mechanical
Failure41%
The cause classification of major industrial accidents
Piping systems
TanksReactors
DrumsPumps/Comp.
H/ETowers
Heaters/BoilersOthers/Unknown
00 2020 2525 3030 35351515101055Number of Failures
-Abroad (1992-2001) From NBBI Annual Report
Equipment Failure Category in Hydrocarbon-Chemical IndustryEquipment Failure Category in Hydrocarbon-Chemical Industry
Over 80% of the Equipment- Caused by the Failure
to Pressurized equipment
�. Introduction (3)�. Introduction (3)
�. RBI (1)�. RBI (1)
• RBI is a method for using risk as a basis to prioritize and manage the efforts of an inspection activity.
- Risk = LOF (likelihood of failure) × COF (consequence of failure)
• An effective risk based inspection activity results in reduced risk level for a given inspection level.
• In an operating plant, a relatively large percentage of the risk is usually associated with a small percentage of equipment.
• A RBI methodology permits the shift of inspection and maintenance resources to provide a higher level of coverage on the high risk items and an appropriate effort on lower risk equipment.
• For example, API 581 guideline- Level 1 (Qualitative RBI)- Level 2 (Semi-quantitative RBI)- Level 3 (Quantitative RBI)
Damageconsequence
category
Likelihoodcategory
Healthconsequence
category
Choose the highest from two
consequenc e
categories
Qualitative RBI
Start
Plant databaseSelect a set of hole size
Plant database
Estimate likelihood of leak
Estimate consequence
Risk = LOF × COF
Semi-quantitative RBI Quantitative RBI
Convert to a risk matrix using likelihood category and consequence category
Suggest each equipment risks after sum of all
scenarios
Semi-quantitative RBIor
Quantitative RBI
Start
Risk matrix
Qualitative RBI process Semi-quantitative and Quantitative RBI processes
�. RBI (2)�. RBI (2)
• Risk Evaluation Process based on API 581
Plant DB
DatabaseManagement
System
DatabaseManagement
System RBI DB
Material DB
ADOConnection
ADOConnection
Risk AssessmentProgram
Risk AssessmentProgram
MaterialManagement
Program
MaterialManagement
Program
DataData
PicturePicture
AssessmentResult
AssessmentResult
DocumentDocumentGraphic
UserInterface
GraphicUser
Interface
Presentation Layer Application Layer Database Layer
- Window Environment
- Visual C++, Visual Basic
- Microsoft Access 2000- Visual Basic
�. Development of RBI program (1)�. Development of RBI program (1)
• The 3-tier structure of proposed RBI program
�. Development of RBI program (2)�. Development of RBI program (2)
• List of input data for using the KGS-RBITM
P&ID No.PFD No.Stream No.Inventory Group NameMaterialService Start DateDesign Life (yr)
P&ID No.PFD No.Stream No.Inventory Group NameMaterialService Start DateDesign Life (yr)
Length (mm)Diameter (mm)Thickness (mm)Operating Pressure (kg/cm2)Operating Temp(C.)Design Pressure (kg/cm2)Design Temp (.C)Insulation (Y/N)Lining TypePWHT (Y/N)
Length (mm)Diameter (mm)Thickness (mm)Operating Pressure (kg/cm2)Operating Temp(C.)Design Pressure (kg/cm2)Design Temp (.C)Insulation (Y/N)Lining TypePWHT (Y/N)
No. of ValvesNo. of BranchesNo. of Injection PointsNo. of ConnectionsNo. of NozzlesConstruction CodeVibration MonitoringPlanned ShutdownUnplanned ShutdownStability RankingRV MaintenanceFouling TendencyCorrosive Service (Y/N)Very Clean Service (Y/N)
No. of ValvesNo. of BranchesNo. of Injection PointsNo. of ConnectionsNo. of NozzlesConstruction CodeVibration MonitoringPlanned ShutdownUnplanned ShutdownStability RankingRV MaintenanceFouling TendencyCorrosive Service (Y/N)Very Clean Service (Y/N)
Rep. MaterialInitial fluid stateToxic MaterialToxic PercentDetection RatingIsolation RatingMitigation SystemsLiquid PercentGas Density (kg/m3)Inventory Input TypeInventory (User input)
Rep. MaterialInitial fluid stateToxic MaterialToxic PercentDetection RatingIsolation RatingMitigation SystemsLiquid PercentGas Density (kg/m3)Inventory Input TypeInventory (User input)
Include Environmental Cleanup cost % Released from Diked areaRelease TypeType of FoundationMethod of DetectionDetection Times
Include Environmental Cleanup cost % Released from Diked areaRelease TypeType of FoundationMethod of DetectionDetection Times
Input Data(Excel File)Input Data(Excel File)
Equipment InformationEquipment Data Likelihood Data
Consequence Data
Financial Data
�. Development of RBI program (3)�. Development of RBI program (3)
• Material management program
�. Development of RBI program (5)�. Development of RBI program (5)
• Qualitative RBI module
�. Development of RBI program (6)�. Development of RBI program (6)
• Semi-Quantitative RBI module
API 581 method Proposed RBI method
�. Development of RBI program (7)�. Development of RBI program (7)
• Quantitative RBI module
API 581 method Proposed RBI method
�. Application of proposed RBI program�. Application of proposed RBI program
• To verify the applicability of the proposed RBI program, proposed RBI program apply to Naphtha Cracking Center.
• The NCC system in this study has been operated for 14 years since it started to produce in 1992.
• The NCC process can largely be divided into four phases
• In the NCC plant to construct RBI; assessment was made on 742 fixed equipments and 1,258 piping systems except utility unit.
Quenching
Cracking Heater
Compression
Distillation
NCC Plant
NCC Plant
5 39 5 15 47 21
4 142 11 109 310 135
3 46 3 38 76 98
2 260 7 195 204 237
1 1 0 1 0 0
A B C D E
Like
lihoo
d of
Fai
lure
Consequence of Failure
NCC Plant Risk DistributionHigh15%
Medium30%
MediumHigh39%
Low16%
�. Result of RBI for NCC plant (1)�. Result of RBI for NCC plant (1)
• RISK Distribution of NCC Plant
A-(Cracking Heater) ProcessHigh3%
Low22%
Medium39%
MediumHigh36%
B-(Quenching) ProcessHigh8% Low
57%
Medium19%
MediumHigh16%
C-(Compressing) ProcessHigh4%
Low14%
Medium54%
MediumHigh28%
D-(Distillation) ProcessHigh26%
Low5% Medium
20%
MediumHigh49%
�. Result of RBI for NCC plant (2)�. Result of RBI for NCC plant (2)
• RISK Distribution for processes
PipeHigh20%
Low5%
MediumHigh45%
Medium30%
ColumnHigh6% Low
31%Medium
High29%
Medium34%
DrumHigh7% Low
38%
MediumHigh19%
Medium36%
�. Result of RBI for NCC plant (3)�. Result of RBI for NCC plant (3)
• RISK Distribution of NCC Plant
Heat ExchangerHigh8% Low
34%
MediumHigh35%
Medium23%
FilterHigh0%
Low75%
MediumHigh6%
Medium19%
Tank
Medium49%
MediumHigh33%
Low18%
High0%
1
10
100
1000
10000
1000001000000
Sum
mat
ion
of T
MSF
COLUMN
DRUMEXCHANGER
HEATER
PIPE
Total : Thinning
Total : SCCTotal : HTHA
Total :Brittle Fracture
Total : External Damage(CUI)
Total : ThinningTotal : SCCTotal : HTHATotal :Brittle FractureTotal : External Damage(CUI)
�. Result of RBI for NCC plant (5)�. Result of RBI for NCC plant (5)
• Analysis of damage factor for equipments and pipes by high risk
D. Process (d)
1
10
100
1000
10000
NCC-8B-P
-4104
-BA8-R
NCC-8B-P
-4133
-BA8-R
NCC-8B-P
-4134
-BA8-R
NCC-8B-P
-4135
-BA8-R
NCC-8B-P
-4277
-BA1
NCC-E-D
A402-B
TM
NCC-E-D
A403-B
TM
NCC-E-E
A403A-T
S
NCC-E-E
A403B-T
SNCC-E
-EA40
4
NCC-E-E
A436-T
S
NCC-E-E
A437-T
S
NCC-E-E
A603-T
SNCC-E
-EA604
NCC-E-FA40
3NCC-E
-FF301A
NCC-E-FF30
1B
NCC-2B-P
-3076
-BK2-R
Equipments
CoF
(m2)
0.0000001
0.000001
0.00001
0.0001
0.001
0.01
0.1
1
LoF
(yea
r)
Consequence of Failure
Likelihood of Failure
36
Inventory No.
PipesPipes
ExchangerColumn
�. Result of RBI for NCC plant (4)�. Result of RBI for NCC plant (4)
• CoF & LoF Results with High Risk
�. Result of RBI for NCC plant (5)�. Result of RBI for NCC plant (5)
• Inspection interval by Risk
Inspection Interval (yr) Total (%)
1 262 13.10 4 593 29.65 6 827 41.35 8 318 15.90
Total 2000 100.00 262
593
827
318
0 200 400 600 800 1000
1 year
4 year
6 year
8 year
Inspection Interval
�. Conclusion�. Conclusion
• Based on risk ranking for the whole NCC plant, High Risk areas which need urgent risk-relieving measures formed about 15 percent, with piping system forming the largest part by equipments.
• Based on risk assessment for each unit process of the NCC plant,
piping systems and the heat exchanger in the distillation process operated at low temperature showed remarkable brittle fracture and SCC, requiring special attention for them.
• Among equipments, risk was highest for pipe, followed by heat exchanger, drum, and column; in particular, the heat exchanger showed high risk due to significantly low inspection efficiency and inspection methodology in internal test.
• Based on management systems assessment from interviews with relevant workers, training, emergency response, and incident investigation got generally low scores in operating the NCC plant, which recommends complementary measures in the future.
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