NTSB Safety Recommendation P-87-019

NTSB safety recommendation P-87-019.

THE NTSB RECOMMENDS THAT THE WILLIAMS PIPELINE COMPANY: ADD A LOW DISCHARGE PRESSURE AUTOMATIC SHUTDOWN CONTROL TO AUTOMATIC SHUTDOWN CONTROLS AT THE MINNEAPOLIS TERMINAL, AS WELL AS AT OTHER TERMINALS.

Priority: CLASS II

Overall Status: Closed - Acceptable Alternate Action

Issued Date: 1987-09-09

Adopted Date: 1987-07-20

Overall Date Closed: 1989-07-12

Synopsis: ABOUT 4:20 A.M. ON JULY 8, 1986, LINE 2N, AN 8-INCH PRODUCTS PIPELINE OPERATED BY WILLIAMS PIPE LINE COMPANY (WPL) AT MOUNDS VIEW, MINNESOTA, RUPTURED. UNLEADED GASOLINE UNDER 1,434 PSIG SPEWED FROM A 7 1/2-FOOT-LONG OPENING ALONG THE LONGITUDINAL SEAM OF THE PIPE. VAPORIZED GASOLINE COMBINED WITH AIR AND LIQUID GASOLINE FLOWED ALONG NEIGHBORHOOD STREETS. ABOUT 20 MINUTES LATER, THE GASOLINE VAPOR WAS IGNITED WHEN AN AUTOMOBILE ENTERED THE AREA. FOLLOWING AN EXPLOSION-LIKE NOISE, FIRE SPREAD RAPIDLY ALONG THE PATH OF THE LIQUID GASOLINE. TWO PERSONS WERE BURNED SEVERELY AND LATER DIED, AND ONE PERSON SUFFERED SERIOUS BURNS. THERE WAS SUBSTANTIAL PROPERTY DAMAGE AND SOIL AND WATER POLLUTION.

Ntsbnumber: DCA86AP014

Report Number: PAR-87-02

Addressee Name: Williams Pipeline Company

Addressee Status: Closed - Acceptable Alternate Action

Addressee Date Closed: 1989-07-12

Addressee Organization Type: P-Private Industry

Communication Date: 1989-02-09

Communication Type: Official Correspondence

Communication Contents: WILLIAMS RECENTLY BEGAN FULL SCALE OPERATION OF ITS NEW SUPERVISORY CONTROL AND DATA ACQUISITION (SCADA) SYSTEM. THE SCADA SYSTEM IS A CENTRALIZED COMPUTER-BASED CONTROL SYSTEM WHICH UTILIZES STATE-OF-THE-ART COMMUNICATIONS AND PROCESS CONTROL TECHNOLOGY TO INTEGRATE INFORMATION PROCESSING, PIPELINE CONTROL AND COMMUNICATIONS SYSTEMS. THE SCADA SYSTEM COLLECTS DATA FROM ALL REMOTE FIELD LOCATIONS ALONG THE PIPELINE (PUMPING STATIONS, TRUCK LOADING TERMINALS, TANK FARMS, ETS.), PROVIDING THE DISPATCHER WITH A COMPLETE VISUALIZATION OF THE PIPELINE OPERATION. AMONG OTHER SOPHISTICATED MONITORING CAPABILITIES, THIS NEW SCADA SYSTEM ALLOWS THE DISPATCHER TO SET PARAMETER ALARMS THAT WILL SOUND AN ALERT SHOULD ANY CONTROL SETTINGS EXCEED OR FALL BELOW DISPATCHER DEFINED THRESHOLDS. REMOTE STATUS SIGNALS TAKE ONLY 5 SECONDS (SCAN TIME FOR THE PREVIOUS SYSTEM WAS 30-45 SEC) TO REACH THE DISPATCH CONTROL CENTER, THUS THE DISPATCHER IS ABLE TO INITIATE IMMEDIATE REMEDIAL ACTION IN THE EVENT OF AN ABNORMAL CONDITION, SUCH AS A SUDDEN DROP IN PUMP DISCHARGE PRESSURE. ANOTHER INTEGRAL COMPONENT OF THE NEW SCADA IS A COMPUTERIZED LEAK DETECTION SYSTEM (UNDER DEVELOPMENT SINCE 1982), CAPABLE OF INDICATING TO THE DISPATCHER THE POSSIBLE PRESENCE OF A LEAK WITHIN THE PIPELINE NETWORK. LEAK DETECTION IS PERFORMED BY TWO INDEPENDENT METHODS--VOLUME BALANCE, AND PRESSURE-FLOW DEVIATION. THESE TWO MECHANISMS COMPLEMENT EACH OTHER TO PROVIDE ADVANCE NOTICE OF POTENTIAL LEAKS AND TIMELY INFORMATION REGARDING THEIR SIZE AND LOCATION. WILLIAMS' SCADA AND LEAK DETECTION SYSTEMS ARE UNQUESTIONABLY THE MOST SOPHISTICATED IN THE PIPELINE INDUSTRY.

Addressee Organization Type: P-Private Industry

Communication Date: 1989-10-10

Communication Type: Official Correspondence

Addressee Organization Type: P-Private Industry

Communication Date: 1989-07-12

Communication Type: Official Correspondence