RELIABILITY ISSUES IN PIPELINES A CASE STUDY. Addl. Director. Oil Industry Safety Directorate

Transcription

1 RELIABILITY ISSUES IN PIPELINES A CASE STUDY Addl. Director Oil Industry Safety Directorate

2 Structure of Presentation Backdrop Reliability & Safety Case Study Summary

3 PIPELINE NETWORK Mundra Kandla Vadinar Sidhpur Kot Jalandhar Rewari Sanganer Ajmer Jodhpur Chaksu Dahej Bhatinda Sangrur Panipat Hazira Ambala Roorkee Najibabad Meerut Delhi Mathura Lucknow Tundla Kanpur Chittaurgarh Ahmedabad Koyali Ratlam Bangalore AFS Sankari Raipur Bangalore Chennai Asanur Trichy Korba Barauni Ranchi Chennai AFS Siliguri Rajbandh Paradip Haldia Bongaigaon Kol AFS Mourigram LEGEND TOTTAL Guw AFS Guwahati Product LPG Crude Oil KM R-LNG Tinsukia Digboi KM KM 2000 KM 9000 KM 15000KM Madurai 3

4 Cross Country Pipeline System

5 Leak site located in a remote area with difficult terrain. LEAK SITE

6 View of Challenging Gradient w.r.t. Pipeline Maintenance

7 A CRACK AT SITE OF DENT/BUCKLE.

8 RELIABILITY & SAFETY CAN T BE SEPARATED Design Reliability Safety Operations Reliability Maintenance Reliability 8

9 DESIGN RELIABILITY Design reliability achieved by : 1. Compliance with the appropriate standards (API, ASME & OISD). 2. Selection of the grade of pipe material and wall thickness of pipe, type of valves and other pipe fittings. 3. Various factors like internal pressure, static loadings and weight effects of the pipe etc. are taken into consideration throgh STD. 4. Identification of high consequence areas & location class. 5. Special protection at crossings like river/canal, rail, road etc., 6. HAZOP and Risk Analysis should be done at design stage 9

10 Design reliability achieved by : DESIGN RELIABILITY 7. Location of Sectionalizing valves is important. 8. Sectionalizing valves should be MOV (Motor Operated Valve) 9. Review in P&ID for ensuring feature of de-pressurization and station bypassing. 10. Shutdown & isolation logic in control system. 11. Provision of SCADA systems for continuous monitoring and control of remotely located Sectionalizing Valve. 12. Leak detection system with provision of identification of leak location. 13. External coating & cathodic protection for external corrosion control. 14. Inhibitor injection for internal corrosion control case. 10

11 OPERATION RELIABILITY Operation reliability achieved by : 1. Comply with standard operating procedures (SOP). 2. Pressure set points etc. should be appropriately defined in the operation philosophy. 3. ESD logic (cause and effect matrix) should be available in control room. 4. Pigging has to be carried out as per guidelines 5. The results of the pig-residue analysis should be analysed. 6. Safety System should not be bypassed. 7. Ensure dedicated, reliable and standby communication system (OFC, leased line etc.) 8. Ensure reliable functioning of SCADA system. 11

12 OPERATION RELIABILITY Operation Reliability Achieved By : 9. Hand operated valves (HOV) installed on old pipelines should be converted into motor operated valve (MOV) for remote operation and prompt action for sectionalisation of Pipeline. 10. Proper analysis of cathodic protection monitoring reports. 11. Any change w.r.t. Basic design conditions should be done after proper study/ analysis and through a proper Management Of Change procedure 12. Human Reliability: a. Ensure availability of Operation manual b. Deploy adequately trained and skilled manpower for pipeline operations. c. Training on auxiliary system like CP, SCADA, ESD, Earthing and FF equipments etc. d. Training on How to handle Emergency situation. c. Motivation, recognition and skill development of manpower should be looked into 12

13 MAINTENANCE CONSIDERATIONS 1. Aim is to minimize breakdown maintenance 2. More focus to be given on predictive & preventive maintenance. 3. Condition based monitoring should be encouraged. Operators must be sensitive to understand the language of the machine. 4. All routine inspection results (CP survey, Coating survey, Soil Resistivity, IPS, Pig residue analysis etc.) should be analyzed and accordingly action should be planned. 13

14 MAINTENANCE CONSIDERATIONS Pigging is a very important activity in pipeline Pipeline Pigging - Pigs are inserted into the pipeline while it is operational and are carried along by the fluid being pumped. Appropriate pigs to be used (foam pigs instead of scrapper pigs is not proper). CLEANING PIGS 14

15 MAINTENANCE CONSIDERATIONS 1. CLEANING PIG - Provide a way to clean debris and scale from the inside of the pipe, 2. INTELLIGENT PIG - Inspect or identify type of defects like metal loss, dent and crack etc. of the pipe. INTELLIGENT PIG 15

16 MAINTENANCE CONSIDERATIONS Pipeline coating & cathodic protection Protective Coating : To prevent direct contact between the Pipe and the environment, to isolate the metallic pipe and to protect from corrosion. Coating Surveys like DCVG/ Pearson survey is carried out to identify coating defects. 16

17 CASE STUDIES-OISD 17

18 CATASTROPHIC FAILURE DUE TO POOR MAINTAINANCE NATURAL GAS PIPELINE RIVER BRIDGE ORIGINATING STATION 18" (API 5L X-60) SV-1 SV-2 SV-5 SV-4/ I P HIGHWAY X-ING SV-3 (CANAL) (PIGGING STATION) RIVER X-ING SV-6 SV-7 SV-8 POWER PLANT Length of pipeline Dia of Pipeline Flow: Pressure: Approx 200 KM 18 OD 0.7MMSCMD 42 Kg/cm2

19 Background CATASTROPHIC FAILURE DUE TO POOR MAINTAINANCE Cross country pipeline supplying Natural Gas to power plant. The pipeline was being operated at a lower flow rate. Pipeline was transporting wet gas. The gas contained CO2 and some traces of Sulphur. Leakage took place at the lowest point where the pipeline was crossing a canal at 6 o clock position. There has been a history of previous leaks near the place of accident Leaks were repaired by clamping. After repairing damaged coating was not repaired.

20 Background CATASTROPHIC FAILURE DUE TO POOR MAINTAINANCE Only foam pig was used for cleaning. It was raining on the day of the incident, so we inferred that vapour cloud of highly flammable hydrocarbon could not disperse due to heavy weather. A tea stall owner. who turned on the stove in the morning, possibly provided the source of ignition. A major explosion occurred in Pipeline gave multiple causalities.

21 CATASTROPHIC FAILURE DUE TO POOR MAINTAINANCE Fire extinguishing took 2 hours. There was a long delay in closing the nearby sectionalising valve (SV). If remote operation of SV was functional, the extent of damage could have been reduced. Root Cause of Incident Leak due to internal corrosion because of presence of condensate. Presence of water and CO2 form weak Carbonic acid, which induce internal corrosion. Improper pigging foam pig used instead of scrapper pigs. Pig residue analysis not carried out. Use of wet natural gas instead of dry natural gas. Not using corrosion inhibitor.

22 CATASTROPHIC FAILURE DUE TO POOR MAINTAINANCE Recommendations and Lessons Learnt Proper cleaning pigging to be carried out regularly followed by pig residue analysis. Instrumented pig survey to be carried out periodically and the anomaly rectification to be carried out as per the recommendations. Dehydration facility must be provided for removal of water and condensate prior to feeding natural gas in the pipeline. Corrosion inhibitor to be used in the line as per requirement. Proper maintenance and inspection practice to be followed. External Coating to be repaired promptly In addition to OFC communication there should be a leased line as back-up. Remote operation of sectionaling valve to be restored.

23 EXAMPLES OF POOR MAINTAINANCE Damaged condition of coating Condensate in field after leak

24 Summary MAINENANCE ACTIVITIES AND SCHEDULE AS GIVEN IN STANDARDS MUST BE ADHERED TO. INSPECTION RESULTS SHOULD BE PROPERLY ANALYSED AND RECOMMENDATIONS ADHERED TO. FOCUS SHOULD NOT BE LIMITED TO DESIGN ASPECT ONLY BUT ALSO ON OPERATION AND MAINTENANCE RELIABILITY.

25 THANK YOU