Transocean Blind Shear Ram In The Gulf of Mexico Disaster

Appendix Z .

Hydraulic analyses of BOP control system (from ultra Deep) ,one of scenarios that have been investigated is operating the EDS/Auto shear system “, the investigation found strong indications on that the EDS/Auto shear system haven’t worked as intended. There have been signs of leakage in the St-lock line and the question is raised how large leakage can the system have and still cut the drill pipe. Scenario 5 :failure in the EDS(Auto shear )system .This scenario has been stimulated to identify possible failures that can prevent the BSR from cutting pipes and you can see from figures the leakage causes a continuously loss of hydraulic fluids as soon as “ the Auto shear “ function is activated.

On the other hand, there are two other issues which are not less impotent as I read in other reports(Chief Counsel‘s report)  - first one , Federal regulations required the Deepwater Horizon to have a BOP that included a blind shear ram (BSR). The blind shear ram is designed to cut drill pipe in the well and shut in the well in an emergency well control situation. But even if properly activated, the blind shear ram may fail to seal the well because of known mechanical and design limitations. In order for a blind shear ram to shut in a well where drill pipe is across the BOP, it must be capable of shearing the drill pipe. And blind shear rams are not always able to perform this critical function, even in controlled situation .Blind shear rams are not designed to cut through multiple pieces of drill pipe or tool jointsconnecting two sections of drill pipe. It is thus critically important to ensure that there is a piece of pipe, and not a joint, across the blind shear ram before it is activated. This fact prompted a 2001 MMS study to recommend every BOP to have two sets of blind shear rams such that if a tool joint prevented one ram from closing, another adjacent ram would close on drill pipe and would be able to shear the pipe and shut in the well. MMS never adopted the recommendation.

The Horizon‘s blowout preventer had only one blind shear ram. Sections of drill pipe are joined by a tool joint at each interval and are often about 30 feet in length, though some of the drill pipe used on the Horizonvaried in length. If one of those joints was in the path of the blind shear ram at the time of attempted activation, as portrayed in The figure shown that the ram would have been unable to shear the pipe and shut in the well.

The second issue  is BOP Recertification,

Recertificationof a blowout preventer involves complete disassembly and inspection of the


It was well known by the rig crew and BP shore-based leadership that the Deepwater Horizon

blowout preventer was not in compliance with certification requirements. BP‘s September

2009 audit of the rig found that the test ram, upper pipe ram, and middle pipe ram bonnets

were original and had not been recertified within the past five years. According to an April

2010 assessment, BOP bodies and bonnets were last certified December 13, 2000, almost

10 years earlier.

Failure to recertify the BOP stack and diverter components within three to five years may have violated the MMS inspection requirements

Transocean did not recertify the BOP because it instead applied ?condition-based

Maintenance. According to Transocean‘s Subsea Maintenance Philosophy, ?the condition of

the equipment shall define the necessary repair work, if any. Condition-based maintenance

does not include disassembling and inspecting the BOP on three- to five-year intervals, a

process Transocean subsea superintendent William String fellow described as unnecessary.

According to String fellow, the rig crew instead tracks the condition of the BOP in the Rig

Management System and ?if we feelthat the equipment is—is beginning to wear, then we

make…the changes that are needed. Transocean uses condition-based monitoring to inspect

all of its BOP stacks in the Gulf of Mexico. According to Transocean witnesses, its system of

condition-based monitoring is superior to the manufacturer‘s recommended procedures and can

result in identifying problems earlier than would occur under time-based intervals. The Chief Counsel‘s team disagrees. Condition-based maintenance was misguided insofar as it

second- guessed manufacturer recommendations, API recommendations, and MMS regulation.

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