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06-17-13: USCG: Recent Failures Of Dynamic Positioning (DP) Systems On MODUs

August 7, 2013, 9:18 am

UNITED STATES COAST GUARD – MARINE SAFETY ALERT

Inspections and Compliance Directorate

June 17, 2013

Washington, DC

RECENT FAILURES OF DYNAMIC POSITIONING (DP) SYSTEMS ON

MOBILE OFFSHORE DRILLING UNITS

 

This Safety Alert addresses dynamic positioning incidents resulting in a loss of position on drillships.

A loss of position during a critical activity may result in a loss of well control and severe

consequences including loss of life, pollution, and property damage. Critical activities are those

activities where the consequences of equipment failure or loss of position are greater than under

normal operating circumstances. Two examples would be a MODU conducting well operations with

non-shearables through the blowout preventer (e.g., the blowout preventer's shear ram(s) cannot

shear) or when the time to terminate operations is unacceptable (e.g., the MODU crew cannot

reposition the non-shearable away from the BOP's shear ram in the time required to disconnect).

 

Recent incidents involving drillship loss of position and emergency disconnects have highlighted the

importance of operating a dynamically positioned drillship within its design limits, ensuring dynamic

positioning competency levels and ensuring appropriate precautions are taken during maintenance

and testing of critical equipment. A loss of position on a dynamically positioned drillship can be

mitigated by following dynamic positioning system guidance published in the ‘‘DP Operations

Guidance Prepared through the Dynamic Positioning Committee of the Marine Technology Society to

aid in the safe and effective management of DP Operations,’ March 2012 Part 2 Appendix 1

(dynamically positioned MODUs), available at:

 

http://www.dynamic-positioning.com/dp_operations_guidance.cfm .

 

See our notice in the Federal Register (77 FR 26562) available at:

 

http://www.uscg.mil/hq/cg5/cg521/docs/DP_FR_Notice_2012-10669.pdf .

 

In two recent incidents, dynamically positioned drillships lost functional thrusters due to an electrical

disturbance when attempting to reconnect a faulty thruster after maintenance. When the thruster was

reconnected it was not electrically isolated from other thrusters and the thrusters did not “ride through”

the disturbance causing loss of thrust. During these incidents the drillship crews were unable to

restore all functional thrusters and as a consequence these drillships lost position and had to initiate

the emergency disconnect sequence (EDS).

 

In another incident a dynamically positioned drillship encountered severe weather with high, shifting

winds that caused it to lose position and initiate the EDS. Despite receiving a weather alert for severe

thunderstorms and high winds well before this incident, only half of the available diesel generators

were on line when the storm hit and the DP Operator (DPO) ordered a significant heading change

with a high rate of turn when the drillship began to lose position. The drillship was unable to achieve

the ordered heading or bring all generators online before it lost position and had to initiate the EDS.

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Based on these incidents, the U.S. Coast Guard recommends that owners and operators of

dynamically positioned MODUs operating on the U.S. Outer Continental Shelf:

 

  • • Include appropriate material on preventing these incidents in training programs for DPOs and

other key DP personnel. Training programs should maximize use of DP simulators to gain

proficiency in maintaining heading (dynamically positioned drillships) and ensuring equipment

is ready ahead of severe weather, ensuring communications with the drill floor (e.g. use of

“blue advisory”/risk assessment) and re-establishing thrust in emergency situations. (See

Marine Technology Society (MTS) MODU Operations Guidance Section 4.13 and IMCA M

117 Rev.1 Appendix 4).

 

  • • Develop and implement a Critical Activity Mode of Operation (CAMO) and a Well Specific

Operating Guideline per MTS, “DP Operations Guidance” to ensure that the most reliable DP

system configuration is used during critical activities. Develop and utilize a CAMO for any

activity you or your lessee identifies as critical. When developing a CAMO, consider requiring

open bus operation during critical activities to prevent a worst case failure with a potential for

zero thrust in excess of your drift off time to the Point of Disconnect (See MTS DP MODU

Operations Guidance Section 4.8 and Appendix C “Example of a CAMO”, “Power

Distribution”).

 

o It may be possible to make a common power system fully fault tolerant in respect of

single failure criteria for DP Class 2 and DP Class 3. However, in such designs fault

tolerance depends on a very comprehensive range of protective functions and on many

items of equipment being able to perform to capacity. Operating the power plant as

two or more independent power systems reduces dependence on protective functions

and vulnerability to hidden failures. It does not remove all common points between

redundant systems. The potential to lose one part of the system is higher but the

potential to lose the complete system is reduced (See MTS “DP Vessel Design

Philosophy Guidelines” Section 10.8).

 

  • • Perform testing aboard MODUs to ensure functional thruster drives will ride-through a system

disturbance. This testing should indicate how the system will react during a significant bus

disturbance such as a short circuit on the main switchboard. Where ride-through capability is

an essential part of the DP redundancy concept it should be proven by live short circuit and

ground fault testing per Section 9.2.5 of the MTS “DP Vessel Design Philosophy Guidelines”.

This testing should be incorporated into the vessel DP Proving Trial (5-year).

 

  • • Perform regular thermal imaging surveys of DP system electrical equipment (e.g., switchgear,

drives, motor controllers, etc.) as part of a preventative maintenance program to provide early

detection of faulty or loose connections.

 

This Safety Alert is provided for informational purposes and does not relieve any foreign or domestic

requirement. Developed by the Coast Guard Outer Continental Shelf National Center of Expertise.

For additional information contact Commander James Rocco: james.v.rocco@uscg.mil .

 

Distributed by the Office of Investigations and Casualty Analysis: http://Marineinvestigations.us

To subscribe:kenneth.w.olsen@uscg.mil

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06-11-13: New Orleans Navigation Restoration Committee Activated for 2013 Hurricane Season

August 7, 2013, 9:17 am

Navigation Restoration Team:  A 'dry run' Navigation Restoration Conference Call was held on Tues, 11 June 2013.

Comments (1411) »


06-06-13: NTSB SAFETY ALERT: Improve Your Chances of Survival When Abandoning Ship

August 7, 2013, 9:14 am

Mariners: Improve Your Chances of Survival When Abandoning Ship

 

Good preparation and proper use of safety equipment is key

 

The problem

The NTSB recently investigated an accident that required the crew to abandon a weather-damaged liftboat in near-hurricane-force conditions.1 Several problems leading up to and during the vessel abandonment negatively impacted the 10 crewmembers’ probability of survival once they were in the water, and four of them died as a result:

 

1 Personnel Abandonment of Weather-Damaged US Liftboat Trinity II, with Loss of Life, Bay of Campeche, Gulf of Mexico, September 8, 2011. The report is available at www.ntsb.gov, under report number NTSB/MAR-13/01.

 

The company hurricane plan did not account for rapidly and locally developing low pressure weather systems. This reduced the crewmembers’ ability to properly plan for the developing storm and to make an early decision to leave the vessel through routine means before the onset of the storm.

The vessel had recently been equipped with two new inflatable throw-over-type liferafts. However, the liferafts were inflated on deck instead of in the water when the crew prepared to abandon the vessel. This led to the liferafts blowing away from the vessel and vanishing in the high winds and seas. The crewmembers ended up clinging to a lifefloat, which, unlike the liferafts, did not provide out-of-water flotation, shelter from the elements, and nonperishable food and drinking water.

Although the crewmembers had gathered additional food, drinking water, and other supplies while preparing to evacuate, they failed to take these with them.

The vessel was equipped with an emergency position indicating radio beacon (EPIRB), which if activated would have quickly alerted authorities and narrowed the search area. However, the crewmembers did not take the EPIRB with them when they abandoned the vessel. As a result, they spent 3 days in the water before search and rescue assets were able to locate them.

 

 

 

What can mariners do?

 

Develop and execute a thorough weather preparedness plan. Ensure that your plan takes into account surface low pressure systems, nontropical storms, and other weather systems that may form rapidly and locally. (For example, not all hurricanes approach from the east.)

Ensure you know how to use safety equipment. Don’t wait until a real emergency to find out whether you know how to properly use lifesaving equipment. Instead, include in your regular weekly or monthly drills a thorough step-by-step assessment of all such equipment, especially liferafts, which can’t actually be deployed during drills.

Plan before evacuating. Before an emergency, ensure you know your assigned duties and responsibilities―such as who’s bringing what supplies―and ensure the responsible person is aware of the location of those items.

Drill as if it is a real emergency. Conducting realistic drills gets the attention of crewmembers, builds their confidence and proficiency in emergency response procedures, and reinforces a strong safety culture. Review drill performance with crew to identify areas for improvement.

Even in coastal waters, plan for the worst. Despite being close to shore and/or in a normally high-traffic waterway, don’t assume that others will be able to come to your immediate aid, especially if your location changes. Be physically and mentally prepared for the possibility of a prolonged exposure situation.

Follow your plan. In emergency situations involving high stress and exhaustion, ensure all aspects are covered by running through step-by-step emergency procedures in accordance with established checklists. Use shoreside support resources to assist you with this.

Don’t forget the EPIRB. The EPIRB is a vital piece of equipment that can significantly shorten the time necessary to locate and rescue you. Take it with you! In addition, carry a personal locator beacon (PLB); it is an inexpensive and effective device.

Stay together in the water. Search and rescue personnel will more easily spot a group of people in the water than dispersed swimmers.

 

The complete investigation report is available here:  http://www.ntsb.gov/doclib/reports/2013/MAR1301.pdf

NTSB feels that this safety alert stems from and relates to a liftboat operation, the recommendations are very important to the broad spectrum of all commercial, offshore, deep sea,  recreational boating, and other types of seagoing and coastal water operations.

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06-04-13: USCG & BSEE sign agreement for regulating MODUs

July 1, 2013, 8:58 am

WASHINGTON - U.S. Coast Guard Rear Admiral Joseph Servidio, Assistant Commandant for Prevention Policy and Bureau of Safety and Environmental Enforcement (BSEE) Director James Watson signed a Memorandum of Agreement (MOA) for regulating Mobile Offshore Drilling Units (MODU) on the Outer Continental Shelf (OCS).

"The Coast Guard and BSEE share the goal of keeping our oceans clean and offshore workers safe," said Servidio.  "This agreement solidifies the commitment of each of our agencies to work across agency boundaries to promote safety and most effectively use government resources."

Under the current regulatory system, both the U.S. Coast Guard and BSEE have shared responsibilities for the regulation of safety management systems on the OCS. This MOA ensures a comprehensive joint approach in the regulation of MODUs by clearly outlining the responsibilities of each agency for inspection and oversight of the systems and sub-systems associated with mobile offshore drilling units engaged in offshore drilling operations.  The Coast Guard and BSEE will use this MOA to better align policies and procedures while also collaborating on future regulatory projects.

"MODUs are unique and dynamic vessels that are an important part of the offshore oil and gas industry's exploration efforts but as we learned from the Deepwater Horizon tragedy, these highly complex drilling units with their state-of-the-art equipment and ultra-deepwater drilling capabilities must be closely monitored" said Watson. "This agreement between BSEE and the Coast Guard serves as a significant milestone in achieving coordinated oversight of MODUs while continuing our joint effort to improve offshore safety."

The MOA is implemented in accordance with an overarching Memorandum of Understanding (MOU) between BSEE and the Coast Guard signed November 29, 2012. The MOU outlined the efforts of the two agencies to closely coordinate responsibilities for regulation and enforcement on the OCS and for the establishment of future focused agreements such as the one signed today. It was the first MOU between the two agencies since the creation of BSEE following the reorganization of the Mineral Management Service in 2011.

The MOA may be viewed here: http://www.uscg.mil/hq/cg5/cg522/cg5222/mou.asp

More information on the MOU that was signed on November 27, 2012 can be found here: http://www.bsee.gov/BSEE-Newsroom/BSEE-News-Briefs/2012/BSEE---Coast-Guard-Sign-Memorandum-of-Understanding.aspx

Comments (179) »


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