CONSOLIDATED EDISON CO OF NEW YORK

Incident Narrative

ON SEPTEMBER 23, 2015 A BIENNIAL REMOTE CLOSURE TEST OF REMOTELY OPERATED VALVE (ROV) 62190 WAS PERFORMED; AS PART OF THIS PROCEDURE, TWO CLOSURES ARE COMPLETED TO FIRST TEST A FRAME RELAY COMMUNICATION PATH, FOLLOWED BY A WIRELESS COMMUNICATION PATH. INITIAL CONDITIONS WERE ROV 62190 IN THE 100% OPEN CONDITION ON FRAME RELAY COMMUNICATIONS. FLOW THROUGH THE TRANSCO 134TH STREET GATE STATION UPSTREAM OF THE ROV WAS 1700 DTH/H. THE SEQUENCE OF EVENTS IS AS FOLLOWS: 5:07:55 - SET POINT FOR ROV 62190 SET TO 0% OPEN 5:08:02 - ROV 62190 IN TRAVEL 5:09:10 - ROV 62190 43% OPEN - ALARM FOR POSITION 5:10:11 - ROV 62190 0% OPEN - ALARM FOR FULL CLOSURE 5:10:15 - SET POINT FOR ROV 62190 SET TO 100% OPEN 5:10:24 - ROV 62190 IN TRAVEL 5:12:14 - ROV 62190 100% OPEN 5:13:48 - ROV 62190 WIRELESS COMMUNICATION PATH SELECTED 5:14:07 - SET POINT FOR ROV 62190 SET TO 0% OPEN 5:15:04 - ROV 62190 VALVE IN TRAVEL 5:15:04 - ROV 62190 59% OPEN - ALARM GENERATED FOR POSITION 5:16:32 - TRANSCO 134TH STREET FLOW IS 2517 DTH/H 5:16:54 - TRANSCO 134TH STREET PRESSURE IS 346 PSIG - ALARM FOR HI PRESSURE 5:17:17 - ROV 62190 0% OPEN - ALARM FOR FULL CLOSURE 5:17:17 - ROV 62190 NORTH (UPSTREAM) PRESSURE IS 375.7 PSIG - ALARM FOR HI HI PRESSURE. TRENDING SHOWS AN INSTANTANEOUS PRESSURE PEAK AT 396 PSIG; MAOP + 10% EXCEEDED FOR 20 SECONDS (>385 PSIG) 5:17:22 - SET POINT FOR ROV 62190 SET TO 100% OPEN 5:17:32 - ROV 62190 IN TRAVEL 5:18:05 - TRANSCO 134TH STREET PRESSURE IS 288 PSIG - PRESSURE IN NORMAL RANGE 5:18:44 - ROV 62190 NORTH (UPSTREAM) PRESSURE IS 288 PSIG - PRESSURE IN NORMAL RANGE 5:19:58 - ROV 62190 100% OPEN DUE TO CONFLICTING PRESSURE READINGS ON THE SAME LINE THE CONTROLLER NOTIFIED GAS ENGINEERING DURING NORMAL BUSINESS HOURS ON 9/23/15. PRESSURE CONTROL (PC) INSTRUMENTS AND CONTROLS (I/C) VERIFIED TRANSDUCER CALIBRATION FOR BOTH TRANSDUCERS ON 9/24/15. TRANSCO WILLIAMS WAS CONTACTED TO EXTRACT STATION DATA ON 9/24/15; TRANSCO STATED THAT PHYSICAL DATA WOULD BE AVAILABLE WITHIN 24 HOURS. ON 9/25/15 INFORMATION FROM TRANSCO INDICATED A DISCRETE HIGH PRESSURE ALARM IN EXCESS OF 360 PSIG AND TRAVEL OF THE FIRST OF TWO OVER PRESSURE PROTECTION (OPP) DEVICES SET AT 365 PSIG AND 370 PSIG RESPECTIVELY. DUE TO THE HIGH PROBABILITY OF AN EVENT, CENTRAL INFORMATION GROUP (CIG), PUBLIC SERVICE COMMISSION (PSC), AND NATIONAL REPORTING CENTER (NRC) WERE NOTIFIED ON 9/25. POST-ANALYSIS FOUND THAT INTERNAL SPECIFICATION G-11810-29 ""PROCEDURE FOR INSPECTION AND MAINTENANCE OF GAS TRANSMISSION PIPELINES"" MADE NO PROVISION FOR TIME PERIODS BETWEEN VALVE MOVEMENTS TO ALLOW FOR SYSTEM STABILIZATION. REVISION G-11810-30A INCORPORATED A 15 MINUTE STABILIZATION TIME FOR ALL VALVE MOVEMENTS FOR ROV FULL-CLOSURE INSPECTIONS. PROCEDURAL PRACTICE ALSO INCORPORATED REDUCING FLOW TO 0 DTH/H PRIOR TO ANY FULL-CLOSURE TEST OF A ROV.