Pipeline Risk Assessment Ahmad Taufik Metal Performance Assessment Group Engineering Consulting and Training Services dan
Rekayasa Pertambangan - Program Pasca Sarjana
Institut Teknologi Bandung
MENGAPA ADA RISK ?
1. Pipeline memiliki masalah dalam disain & konstruksi 2. Pipeline mengalirkan fluida berbahaya 3. Pipeline sudah dioperasikan untuk waktu yang cukup lama (aging) 4. Adanya mekanisme kerusakan yang terjadi sehingga pipa gagal (mis : akibat faktor lingkungan/korosi)
Damage Mechanism & Failure Modes 1. Fatigue 2. Corrosion 3. Brittle Fracture 4. Buckling / Plastic Deformation 5. Stress Corrosion Cracking 6. Hydrogen Embrittlement
The Origin of Failure 9 9 9 9 9 9 9
Design Faulty Manufacture Defect Construction Defect Operation Misconduct Maintenance/Assembling Inspections Nature
250 No. of Incidents Fatalities Property Damage ($MM)
200
150
100
50
0 1986
1988
1990
1992
1994
1996
1998
2000
DOT Gas Distribution Incidents : 1986-99
Data statistik memperlihatkan bahwa risk dari pipeline dapat dikurangi, dikendalikan, atau diubah tetapi tidak dapat dihilangkan menjadi nol.
FAILURE DATA FOR PIPELINE (contoh di USA & Eropa) 0
10
20
30
40
50
60
70
28.4
Other
33.3 20.9
5.5
Accidently Caused by Operator
5.6 5.2
5.5
Construcion/Operating Error
3.7 3.7
Damage from Outside Forces
58.7 54.6 65.7
0.9
External Corrosion
2.8 4.5
0.9
Internal Corrosion 0 0
1998
1997
1996
DEFINISI Risk adalah produk dari peluang (likelihood / probability) kegagalan dan dampak nya (consequences) yang tidak diinginkan (accidental event).
Risk = Probability of Failure x Consequences of Failure Risk = LoF (t) x CoF (t) Probability adalah peluang terjadinya sebuah kegagalan (0 ≤ p ≤ 100%). P = 0, kegagalan tidak mungkin terjadi, jika P = 1, kegagalan pasti terjadi. Likelihood adalah deskripsi kualitatif dari probability dan frekwensi kegagalan Consequences menjelaskan akibat atau dampak (-) dari sebuah accidental event. Safety adalah perlindungan terhadap publik, lingkungan dan kepemilikan, sedangkan Risk adalah ancaman terhadap pencapaian tujuan tersebut. Hazard (“bahaya”) adalah karakteristik (atau sebuah kelompok karakteristik) yang berpotensi menghasilkan kerugian - loss (mis : flammability, toxicity, reactivity). Pipeline Incident hasil dari satu atau lebih kejadian dalam urutan yang menyebabkan pipeline kehilangan integritas dan kehilangan isinya baik produk cair maupun gas.
KARAKTERISTIK RESIKO 1. Istilah “Risk” artinya kita tidak dapat menentukan secara tepat nilai atau besarnya sebab kedua faktor diatas (peluang kegagalan dan dampaknya) masih memiliki unsur ketidakpastian (uncertainty). 2. Risk memiliki dimensi yang beragam :
a. Score (tanpa satuan, 344, 45, 6B, 1A, ….. ) b. Jumlah kecelakaan/kematian per tahun c. Jumlah kerugian pertahun ($/yr), dsb. 3. Risk memiliki nilai relatif dan tidak dapat berdiri sendiri, jadi
perhitungan risk membutuhkan konsistensi dalam metodologi
Pipeline Risk Assessment
Define Objectives
Risk Assessment
Segment Identification Data & Info Gathering
Likelihood of Failure
Consequences of Failure (Hazard)
Pipeline Risk Management
Flow Chart untuk Pipeline Risk Assessment
Risk Estimation
Acceptable Risk?
No Risk Mitigation
Yes
Maintaining RIsk Level Acceptable Protection
- Performcance Improvement - Conditioning Monitoring Feedback
Risk Management
Design
Maintenance
Pipeline Data
Inspection
Assessment
Risk Management Life Cycle
APA KEUNTUNGAN DARI PENGELOLAAN RISK ?
9 9 9 9
Terjalin komunikasi yang baik antara pipeline operator, regulator, insurer, customer, dan pihak lainnya. Peningkatan safety dan reliability system pipeline. Penurunan biaya operasi, inspeksi dan maintenance pipeline. Keamanan bagi lingkungan dan masyarakat sekitar pipeline
Masukan dalam Perhitungan Risk 9 9 9 9 9 9
Data disain dan kondisi operasi pipa Sejarah kegagalan (jika ada) Rekaman temuan inspeksi Data populasi dan distribusi penduduk Kondisi ROW aktivitas pihak ketiga Kondisi geologi dan iklim
DATA TEKNIS YANG PERLU MENDAPAT PERHATIAN SERIUS : 9 Review dari Fluida (minyak dan gas) 9 Product Hazard dan Faktor Dispersi 9 Sejarah Kebocoran (jika ada) 9 Data Penggalian 9 Suvey Potensial untuk Proteksi Cathodic 9 Survey Cacat Coating 9 Hasil Intelligent Pig 9 dll yang relevan
Probability of Failure atau Likelihood of Failure Peluang kegagalan merupakan komponen pertama dalam perhitungan resiko dan harus dapat ditentukan terlebih dahulu. Peluang kegagalan merupakan indikator utama terhadap integritas struktur dan keandalan pipa terhadap kerusakan yang dihasilkan. Probability of Failure dapat dihitung / ditaksir dari : 1. 2. 3. 4.
Teori Reliability dan Probabilistik (mis : FOSM) Fault Tree Analysis Sejarah / Laju Kegagalan persatuan waktu (Frekwensi of Failure) Sistim score berdasarkan weighting faktor, dsb.
Likelihood of Failure / Frequency of Failure Accident probability tergantung management, human error, dsb. 1. 2. 3. 4. 5.
high low very low rare extremely rare
:
F > 10-2 per year 10-2 > F>10-4 per year 10-4 > F>10-6 per year 10-6 > F >10-8 per year F < 10-8 per year
kondisi
pipa,
Failure rates untuk pipa dengan diameter ½ ”- 2” FAILURE MODES
FAILURE RATES
Small leak
10-9 per hr.m
Break
3.10-11 per hr.m
Failure Rates 5 x 10-4 (per km per yr) Small
x < 20 mm
87%
Medium
20 mm < x < 80 mm
10%
Large
x > 80 mm
3%
Annual Failure Frequency Ranking for One pipeline Category 1 (low) 2 3 (medium) 4 5 (high)
Description So low frequency that event considered negligible.
Frequency <10-5
Event rarely expected to occur.
10-4>10-5
Event individually not expected to happen, but when summarized over a large number of pipelines have the credibility to happen once a year.
10-3>10-4
Event individually may be expected to occur during the lifetime of the pipeline (Typically a 100 year storm)
10-2>10-3
Event individually may be expected to occur than once during lifetime.
>10-2
Consequence of Failure Menjelaskan hasil atau akibat atau dampak (-) sebuah accidental event. Konsekewnsi biasanya dievaluasi dari sisi i) human savety, ii) environmental impact dan iii) economic loss atau besaran lain yang menyebabkan kerugian material atau nonmaterial. Resiko yang tidak diinginkan pada kegagalan pipeline 1.
Fire
2.
Explosion
3.
Pollution
Identifying Potential Consequences for Pipeline Pipeline contents
Human safety
Gas
Relevant
Condensate
Environmental impact
Material Damage Relevant
Relevant
Normally not relevant4 Relevant1
Oil
Relevant
Relevant
Relevant
Water
Normally not relevant
Relevant5
Relevant
Umbilical
Normally not relevant2
Normally not relevant2,3
Relevant
Relevant
Safety Consequence Ranking Category 1 (low) 2 3 (medium) 4 5 (high)
Description No person(s) are injured (not used) Serious injury, one fatality (working accident) (not used) More than one fatality (gas cloud ignition)
Spillage Ranking Category
Description
Amount of release
1 (low)
Non, small or insignificant of the environment. Either due to no release of internal medium or only insignificant release.
~0
2
Minor release of polluting media. The released media will decompose or be neutralized rapidly by air or seawater. Moderate release of polluting medium. The released media will use some time to decompose or neutralize by air or seawater, or can easily be removed.
<1000 tonnes
3 (medium)
4
5 (high)
<10000 tonnes
Large release of polluting medium which can be removed, or will after some time decompose or be neutralized by air or seawater.
<100000 tonnes
Large release of high polluting medium which can not be removed and will use long time to decompose or be neutralized by air or seawater.
>100000 tonnes
Economic Consequence Ranking Category
Description
Production delay/ Downtime
1 (low)
Insignificant effect on operation, small or insignificant cost of repair
0 days
2
Repair can be deferred until scheduled shutdown, some repair costs will occur.
<1 month
3 (medium)
Failure causes extended unscheduled loss of facility or system and significant repair costs. Rectification requires unscheduled underwater operation with pre-qualified repair system before further production.
1-3 months
4
Failure causes indefinite shut down and significant facility of system failure costs. Rectification requires unscheduled underwater operation without pre-qualified repair system before further production, OR Failures resulting in shorter periods of shut down of major parts of (or all of) the hydrocarbon production for the field.
3-12 months
5 (high)
Total loss of pipeline and possible also loss of other structural parts of the platform. Large cost of repair including long time of shut down of production. OR Failures resulting in shut down of the total hydrocarbon production for a longer period.
1-3 years
PIPELINE SECTIONING WO4-24
WO6-18
3" 0.4 km JO4-24
W11-18 10" 0.6 km
WO9-23 JO7-24
J11-18
W10-07 WO6-24 4" 0.48 km
10" 0.48 km
8" 0.48 km 6" 0.48 km
12" 1 km 16-23
12" 0.5 km J06-24
12" 1.2 km JO7-24
10" 1.0 km J05-18
C513-07
Pembagian seksi pipa perlu untuk mengidentifikasi bagian pipeline yang memiliki potensi risk tertinggi.
PRESENTASI RISK - MATRIX Representasi grafis untuk memudahkan pipeline risk (merupakan rangkuman)
mengkarakterisasi
Consequence evaluation Human safety, Environmental Impact Economical loss
Consequence vs damage
1 2 3 4
Frequency estimation
5
5 Frequency vs damage
Not acceptable
4
ALARP region
3 2
Acceptable
1 Frequency ranking
Event Risk matrix
Process description of a risk assessment (figure is olny schematic, actual limits need to be given operator)
5.6 Likelihood of Failure
Likelihood of Failure (CoF)
7.0
Ranking Matrix for "Natural Gas"
4.2
2.8
1.4
0.0 0.0
2.0
4.0
6.0
Consequences of Failure
8.0
10. 0
Consequences of Failure (CoF)
Database of pipelines shown in a risk matrix
Presentasi Risk – Kurva (plot ) Risk Score Vs Lokasi Pipeline 25 Lik e liho o d C o ns e que nc e s R is k S c o re
15 10 5
Lokasi Pipeline (Km)
19
17
15
13
11
9
7
5
3
0 1
Score
20
Penutup dan Kesimpulan 1. Risk assessment perlu dilakukan untuk mengidentifikasi resiko tertinggi dari jalur pipeline (khususnya aging pipeline) 2. Pipa dengan resiko tertinggi dapat dikelola untuk menurunkan level risknya (risk mitigation), apakah peluang kegagalannya yang diturunkan atau dampaknya yang dikurangi. 3. Jika no.1 & 2 dilakukan maka akan terjadi optimasi : i) inspeksi, ii) maintenance, & iii) operational cost yang efektip dengan tingkat safety dan keandalan tinggi dari pipeline.
