Pipeline Risk Assessment

Transkripsi

1 Pipeline Risk Assessment Ahmad Taufik Metal Performance Assessment Group Engineering Consulting and Training Services dan Rekayasa Pertambangan - Program Pasca Sarjana Institut Teknologi Bandung

2 pipa gagal (mis : akibat faktor lingkungan/korosi) 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

3 Damage Mechanism & Failure Modes 1. Fatigue 2. Corrosion 3. Brittle Fracture 4. Buckling / Plastic Deformation 5. Stress Corrosion Cracking 6. Hydrogen Embrittlement

4 The Origin of Failure Design Faulty Manufacture Defect Construction Defect Operation Misconduct Maintenance/Assembling Inspections Nature

5 No. of Incidents Fatalities Property Damage ($MM) DOT Gas Distribution Incidents : Data statistik memperlihatkan bahwa risk dari pipeline dapat dikurangi, dikendalikan, atau diubah tetapi tidak dapat dihilangkan menjadi nol.

6 FAILURE DATA FOR PIPELINE (contoh di USA & Eropa) Other Accidently Caused by Operator Construcion/Operating Error Damage from Outside Forces External Corrosion Internal Corrosion

7 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.

8 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

9 Flow Chart untuk Pipeline Risk Assessment Risk Assessment Likelihood of Failure Define Objectives Segment Identification Data & Info Gathering Consequences of Failure (Hazard) Pipeline Risk Assessment Pipeline Risk Management Risk Estimation Acceptable Risk? Yes Risk Mitigation No Maintaining RIsk Level - Performcance Improvement - Conditioning Monitoring Acceptable Protection Feedback Risk Management

10 Design Maintenance Pipeline Data Inspection Assessment Risk Management Life Cycle

11 APA KEUNTUNGAN DARI PENGELOLAAN RISK? 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

12 Masukan dalam Perhitungan Risk 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

13 DATA TEKNIS YANG PERLU MENDAPAT PERHATIAN SERIUS : Review dari Fluida (minyak dan gas) Product Hazard dan Faktor Dispersi Sejarah Kebocoran (jika ada) Data Penggalian Suvey Potensial untuk Proteksi Cathodic Survey Cacat Coating Hasil Intelligent Pig dll yang relevan

14 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. Teori Reliability dan Probabilistik (mis : FOSM) 2. Fault Tree Analysis 3. Sejarah / Laju Kegagalan persatuan waktu (Frekwensi of Failure) 4. Sistim score berdasarkan weighting faktor, dsb.

15 Likelihood of Failure / Frequency of Failure Accident probability tergantung : kondisi pipa, management, human error, dsb. 1. high F > 10-2 per year 2. low 10-2 > F>10-4 per year 3. very low 10-4 > F>10-6 per year 4. rare 10-6 > F >10-8 per year 5. extremely rare F < 10-8 per year

16 Failure rates untuk pipa dengan diameter ½ - 2 FAILURE MODES Small leak Break FAILURE RATES 10-9 per hr.m 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%

17 Annual Failure Frequency Ranking for One pipeline Category Description Frequency 1 (low) So low frequency that event considered negligible. < Event rarely expected to occur > (medium) Event individually not expected to happen, but when summarized over a large number of pipelines have the credibility to happen once a year. 4 Event individually may be expected to occur during the lifetime of the pipeline (Typically a 100 year storm) 10-3 > > (high) Event individually may be expected to occur than once during lifetime. >10-2

18 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

19 Identifying Potential Consequences for Pipeline Pipeline contents Human safety Environmental impact Material Damage Gas Relevant Normally not Relevant relevant 4 Condensate Relevant Relevant 1 Relevant Oil Relevant Relevant Relevant Water Normally not relevant Relevant 5 Relevant Umbilical Normally not relevant 2 Normally not relevant 2,3 Relevant

20 Safety Consequence Ranking Category Description 1 (low) No person(s) are injured 2 (not used) 3 (medium) Serious injury, one fatality (working accident) 4 (not used) 5 (high) More than one fatality (gas cloud ignition)

21 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. 2 Minor release of polluting media. The released media will decompose or be neutralized rapidly by air or seawater. 3 (medium) 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. 4 Large release of polluting medium which can be removed, or will after some time decompose or be neutralized by air or seawater. 5 (high) 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. ~ 0 <1000 tonnes <10000 tonnes < tonnes > tonnes

22 Economic Consequence Ranking Category 1(low) Description Insignificant effect on operation, small or insignificant cost of repair Production delay/ Downtime 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. 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. 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 months 3-12 months 1-3 years

23 PIPELINE SECTIONING WO4-24 WO6-18 JO4-24 3" 0.4 km W11-18 WO " 0.6 km 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 12" 0.5 km 12" 1.2 km 10" 1.0 km J06-24 JO7-24 J05-18 C Pembagian seksi pipa perlu untuk mengidentifikasi bagian pipeline yang memiliki potensi risk tertinggi.

24 PRESENTASI RISK - MATRIX Representasi grafis untuk memudahkan mengkarakterisasi pipeline risk (merupakan rangkuman) Consequence evaluation Human safety, Environmental Impact Economical loss Consequence vs damage Frequency estimation Frequency vs damage Frequency ranking Risk matrix Not acceptable ALARP region Acceptable Event Process description of a risk assessment (figure is olny schematic, actual limits need to be given operator)

25 7.0 Ranking Matrix for "Natural Gas" Likelihood of Failure (CoF) Likelihood of Failure Consequences of Failure Database of pipelines shown in a risk matrix Consequences of Failure (CoF)

26 Presentasi Risk Kurva (plot ) Risk Score Vs Lokasi Pipeline Likelihood Consequences Risk Score Score Lokasi Pipeline (Km)

27 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.