National
alert from pipeline accident
National alert from pipeline
accident
Regulators urge review
of computer systems
Friday, July 9, 1999
By SCOTT SUNDE
SEATTLE POST-INTELLIGENCER
REPORTER
Breakdowns in the Olympic Pipe Line Co. computer system just before
and during last month's deadly accident in Bellingham have so alarmed federal
regulators that they have issued a nationwide warning.
The federal Office of Pipeline Safety issued the warning this
week to the 2,000 operators of liquid and natural-gas pipelines in the
United States. It urged them to make sure that computer systems used to
operate and monitor pipelines are working properly.
Snip
But on June 10, the system had an internal database error. That
error, plus the demands put on the computer by the leak, "hampered controller
operations," the advisory said.
"The combination of the database error, the inadequate reserve
capacity of the SCADA processor and the unusually dynamic changes that
occurred during the upset condition appear to have combined and temporarily
overburdened the SCADA computer system," regulators said.
"This may have prevented the pipeline controllers from reacting
and controlling the upset condition on their pipeline as promptly as would
have been expected."
Regulators also said that modifications made to the computer system
after it was installed may have caused it to malfunction.
-- Brian (imager@home.com), July 10, 1999
ant
Thanks for the link, and here is the official word from The Office
of
Pipeline Safety.
Home Page
Welcome to the Office of
Pipeline
Safety
ADB99-03
Potential
Service Interruptions
PIPELINE SAFETY ADVISORY BULLETIN
ADVISORY BULLETIN: ADB-99-03 Date: July 7, 1999
To: Owners and Operators of Hazardous Liquid and Natural Gas
Pipeline
Facilities
Subject: Potential Service Interruptions in Supervisory Control and
Data
Acquisition Systems
Purpose: Inform pipeline system owners and operators of potential
operational limitations associated with Supervisory Control and
Data
Acquisition (SCADA) systems and the possibility of those problems
leading
to or aggravating pipeline releases.
Advisory: Each pipeline operator should review the capacity of its
SCADA
system to ensure that the system has resources to accommodate
normal
and
abnormal operations on its pipeline system. In addition, SCADA
configuration
and operating parameters should be periodically reviewed, and
adjusted
if
necessary, to assure that the SCADA computers are functioning as
intended.
Further, operators should assure system modifications do not
adversely
affect
overall performance of the SCADA system. We recommend that the
operator
consult with the original system designer.
Background: During an Office of Pipeline Safety (OPS) investigation
of a
recent pipeline incident, OPS inspectors identified inadequate
SCADA
performance as an operational safety concern. Immediately prior to
and during
the incident, the SCADA system exhibited poor performance that
inhibited
the
pipeline controllers from seeing and reacting to the development of
an abnormal
pipeline operation.
Preliminary review of the SCADA system indicates that the processor
load (a
measure of computer performance utilization) was at 65 to 70
percent
during
normal operations. Immediately prior to an upset condition
occurring
on the
pipeline, the SCADA encountered an internal database error. The
system
attempted to reconcile the problem at the expense of other
processing
tasks.
The database error, coupled with the increased data processing
burden
of the
upset condition, hampered controller operations. In fact, key
operator
command functions were unable to be processed immediately prior to
and
during the abnormal operation. It is possible that post
installation
modifications may have hampered the system's ability to function
appropriately.
The combination of the database error, the inadequate reserve
capacity
of the
SCADA processor, and the unusually dynamic changes that occurred
during
the upset condition, appear to have combined and temporarily
overburdened
the SCADA computer system. This may have prevented the pipeline
controllers from reacting and controlling the upset condition on
their
pipeline
as promptly as would have been expected. For further information,
contact
Chris Hoidal, Director, OPS Western Region at 303-231-5701.
-- Brian (imager@home.com), July 10, 1999.