FEBRUARY 25, 2015
The Bureau of Safety and Environmental Enforcement (BSEE) and the U.S. Coast Guard today issued a Joint Safety Alert addressing a dynamic positioning incident involving an Offshore Supply Vessel which resulted in a loss of position while conducting a critical Outer Continental Shelf activity. BSEE and the Coast Guard are issuing this joint Safety Alert to highlight the importance of an Offshore Supply Vessel's Safety Management System and a leaseholder’s Safety and Environmental Management System.
Dynamic positioning (DP) is a computer-controlled system to
automatically maintain a vessel's position and heading by using its own
propellers and thrusters. Position reference sensors, combined with wind
sensors, motion sensors and gyrocompasses, provide information to the computer
pertaining to the vessel's position and the magnitude and direction of
environmental forces affecting its position. Examples of vessel types that
employ DP include, but are not limited to, ships and semi-submersible mobile offshore
drilling units (MODU), oceanographic research vessels and cruise ships.
The computer program contains a mathematical model of the
vessel that includes information pertaining to the wind and current drag of the
vessel and the location of the thrusters. This knowledge, combined with the
sensor information, allows the computer to calculate the required steering
angle and thruster output for each thruster. This allows operations at sea
where mooring or anchoring is not feasible due to deep water, congestion on the
sea bottom (pipelines, templates) or other problems.
Dynamic positioning may either be absolute in that the
position is locked to a fixed point over the bottom, or relative to a moving
object like another ship or an underwater vehicle. One may also position the
ship at a favorable angle towards wind, waves and current, called
weathervaning.
Dynamic positioning is used by much of the offshore oil
industry, for example in the North Sea, Persian Gulf, Gulf of Mexico, West
Africa, and off the coast of Brazil. There are currently more than 1800 DP
ships.
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SAFETY
ALERT
February 24, 2015 Coast Guard Alert 01-15
Washington, DC
BSEE Alert #315
DYNAMIC POSITIONING SYSTEM FAILURES ON OFFSHORE SUPPLY VESSELS ENGAGED
IN OIL AND GAS OPERATIONS IN THE U.S. OUTER CONTINENTAL SHELF
Discussion: This Joint Safety
Alert addresses a dynamic
positioning (DP) incident involving an Offshore Supply Vessel (OSV) which resulted in a loss of position
while conducting a critical
Outer Continental Shelf (OCS) activity.
The OSV was attached
to a wellhead, lost position and severed the wellhead tree causing a lubricant release on the platform deck and to the environment. Immediately prior to the position loss, the OSV had multiple DP system alarms and failures,
including loss of bow thruster
and engine control. No attempt
was made to identify
or correct the causes
of these failures and the operations continued.
At the time of the position loss, the OSV was being utilized
to support pump and electric line equipment
which was connected
to the well at the time of the incident. Specifically, when the vessel lost position, the vessel operator was in the process of removing
a downhole DX plug from the well via wireline.
High pressure pump lines were also connected to the well, although actual
pumping operations were not in progress. When the vessel lost
position, the Christmas tree was sheared from the well because
of the force exerted on it by
virtue of the connected high pressure lines. Severe consequences were averted
because a subsurface safety
valve was activated and there was an absence
of hydrocarbon flow from the well.
The OCS activity
performed was critical
due to the short time to terminate and the potential uncontrollable release of hydrocarbons from a
well with known sustained casing
pressure. The Coast
Guard and the BSEE
are issuing this joint Safety
Alert because we share
jurisdiction on the OCS and wish to
highlight the importance of an OSV’s Safety Management System
(SMS) and a leaseholder’s Safety and Environmental Management System (see Reference
1).
This incident highlights the following
critical issues:
Alarms: The Coast
Guard and BSEE stress the importance of properly acknowledging and investigating all alarms,
and taking immediate and positive
corrective action prior to initiating or proceeding with any critical OCS activity.
SMS: The OSV was not required to and did not have an International Safety Management (ISM) Code certificate. The Coast Guard reminds
OSV owners and operators
that an effective
SMS is essential to safe operations, particularly when those operations are critical OCS activities. Had the OSV implemented an effective SMS, as described in the ISM code, it likely would have:
1. Had
adequate emergency
disconnect capability and procedures for loss of position
events and personnel trained in those procedures. In this case the OSV did not have adequate
emergency disconnect capability,
procedures or training
records;
2. Ceased the critical
OCS activity after experiencing multiple DP system failures - including
engine and thruster loss - and not have resumed the activity
until after correcting the causes of the DP system
failures (see Reference 2).
Dynamic Positioning: The Coast Guard strongly recommends owners and operators of OSVs using DP to
follow DP guidance provided in reference 3 (Marine Technology Society (MTS) DP operations guidance) when conducting critical activities on the U.S. OCS. See the applicable
notice on this topic published in the Federal
Register (77 FR 62247, October 12, 2012) for more details. Had this OSV followed the MTS DP operations guidance
it likely would
have:
1)
Had a DP system that met a minimum of DP Equipment Class 2 (DP-2).
The involved OSV’s DP system
was DP Equipment Class 1 (DP-1), which means that a loss of
position may occur in the event of a
single failure. (see Reference 3,
paragraph 4.1);
2)
Had an Activity
Specific Operating Guideline (ASOG) that
prescribed emergency disconnect procedures and capability to prevent equipment damage and pollution. The involved OSV did not have an ASOG defined. The sample ASOG in MTS DP guidance recommend
the operator should “halt operations
and initiate contingency procedures” for thruster and generator failures,
which this OSV experienced prior to the loss of position incident. (see Reference 3, Appendix C);
3)
Had a Critical Activity Mode of Operation
(CAMO) defined. The involved
OSV did not have a CAMO defined.
The sample CAMO in MTS DP guidance recommend the operator change operating
condition from “normal operations” to “informative/consultative status (risk assess)” when any change occurs to the normal
operations of the DP system, which
this OSV experienced prior
to the loss of position incident. (see Reference 3, Appendix C);
4)
Ensured a structured competence assurance
program was applied to all key DP personnel. At a minimum
DP personnel should be required to demonstrate proficiency in understanding the redundancy concept
and emergency procedures to respond in the event of a DP system failure. (see
Reference 3, paragraph
4.14).
Leaseholder/operator SEMS: BSEE
strongly recommends leaseholders/operators consider
Coast Guard recommendations
for DP vessels when evaluating
potential hazards and establishing/implementing contractor safe work practices in their SEMS program (see 30 CFR §§ 250.1911 and 250.1914). BSEE reminds
leaseholders/operators of their
critical role in ensuring safety and
environmental hazards associated with contracted vessels on their
lease are properly managed.
For example,
leaseholders/operators should ensure hazards associated with a loss of
position by contracted DP vessels are
analyzed and managed with appropriate contractor safe work practices.
For
additional information, contact Lieutenant
Commander Elizabeth Massimi at (504) 671-2156 with the Coast Guard District 8 Prevention Division or Troy Trosclair at 504-736-2923 with the BSEE Gulf of Mexico Region.
Reference 1: BSEE/USCG Memorandum of Agreement OCS-07
“Safety and Environmental Management Systems (SEMS) and Safety Management Systems
(SMS)” (April 30, 2013).
Reference 2: ISM Code Regulations 7 and 10 (2014 ed.).
Reference 3: DP Operations Guidance, Part 2 Appendix 2: DP Project
/Construction Vessels (Dynamic Positioning Committee of the Marine
Technology Society to aid in the safe and effective management of DP Operations (July 31, 2012).
Reference 4: Marine Technology Society Technical
and Operations Guidance (TECHOP)
“Defining Critical Activities
Requiring Selection of Critical Activity
Mode”, TECHOP_ODP_12_(O) (January
2014).