Petrobras P36 Sinking Report

Rio de Janeiro, BrazilJune 22, 2001

InquiryInquiry Commission intoCommission into PP--36 36 AccidentAccident

Carlos HELENO Netto Barbosa Chairman - Drilling and Logistics (Sondagem e Logística) SSE

CID Guilherme P Valerio SMS Corporativo

RONALDO DIAS Roncador Production Assets

Carlos BARTOLOMEU Bastos Barbosa Basic Production Engineering – CENPES

José Antônio de FIGUEIREDO Production Engineering – ENGENHARIA

Luiz Carlos Nery GUARABYRA Corporate Human Resources (RH Corporativo)

Carlos Henrique de Lima Ferreira CIPA (Internal Commission for Accident Prevention) Representati

Pedro Jose BARUSCO Filho E&P-CORP/ENGP/ENMBP

Prof TIAGO Alberto Piedras Lopes UFRJ (Federal University of Rio de Janeiro)/ Coppe

Antônio Carlos Ferreira RANGEL Representative of SINDIPETRO – NF (Petroleum Workers Union)

ScopeScope of of the Investigation and Findingsthe Investigation and Findings

SCOPE OF THE WORK: Determine the causes of the accidentContributing factors resulting in loss of stability of the platformTo recommend measures for the elimination/control of these causes and factors

COMMISSION WAS ASSURED OF TOTAL AUTONOMY AND AUTHORITY

FINAL PRODUCT:Most probable hypothesis explaining events which occurredConclusions and Recommendations

The AccidentMarch 15 2001

Establishing Hypotheses

Testing the Hypotheses

Scop

e of

Ver

ifica

tion

by D

NV

Scop

e of

Acc

iden

t Inq

uiry

Witness Statements Photographs Video Computer Records Documentation

Rejection of HypothesesInteraction Timeline/Hypotheses

Formal Accident Inquiry Immediate CausesBasic CausesRecommendations

Analysis of Management

Final Report

Constructing Timeline of Accident

Raising Data and Information

Investigation MethodologyInvestigation Methodologyof Pof P--36 36 Accident Accident

HAZOP Stability Analysis

Dispersion Model

Explosion Analysis

Visit Jack Bates

Documentary Analysis

INFORMATION COLLATINGINVESTIGATIONINVESTIGATION

PRINCIPAL SOURCE OF INFORMATION (P36) WAS LOST64 INTERVIEWSDOCUMENTATION/MATERIAL RETRIEVED FROM P-36– Records of Ballast Operations– Daily Production Bulletin– Operational Situation Bulletin (SITOP)– Treatment of Irregularities Report (RTA)– Magnetic Files with Records of Fire and Gas and Shutdown Systems

• (Period from 08h00min on March 14 to 04h00min on March 15 2001)

PLATFORM PROJECT DOCUMENTATIONVIDEO TAPES AND PHOTOGRAPHSARTICLES PUBLISHED IN THE MEDIA

Analysis of Photographs and Videos

Normal Operation

After the Accident

After the Loss


Magnetic Files

•Fire and Gas records recovered•11800 entries•1723 entries between 1st and 2nd events (17 minutes )•Work required for processing this data


Project Documentation INFORMATION COLLATINGINVESTIGATIONINVESTIGATION

Timeline Analysis

Date/Time System Description

INVESTIGATIONINVESTIGATION

EVENT

First event. Shaking (jolt). Noise reported as falling deck cargo. Probablemechanical rupture of the starboard emergency drain storage tank.

Verification of pressure loss in the fire tank. PS 70001 alarm sounded

PT-70007 pressure in fire ring fell to 7-bar set point, which automatically starts thetwo seawater pumps (XA/401 A/B/C/E) as well as two fire pumps (XA/401A/B/CE)placing the platform in a FIREFIGHTING MODE.

OUTLET DAMPER VE-006ST. (exhaustion of starboard aft column) closes. Thecorresponding EXHAUSTER (XA-2658) receives the same stop signal (status ofthis ventilator is not indicated in the F&G and E8D system)Waste oil pump XB149A (XB1 49AS) indicates no longer functioningINLET DAMPER VE-002STS (verification of the starboard aft column) closes.Corresponding VENTILATOR (XA-264H) receives the same stop signal (status ofthe ventilator is not indicated in the F&G and E8D system)XB70519B sea water pump electric drawer signal XA/039C (bow /starboard)turning at high speedOUTLET DAMPER DF-5251 – 09 (starboard aft column elevator well) confirmsclosureXS70701 and XS70704 – General Public Alarm A & B is soundedGas is detected on the Main Deck (external area) at the platform bow and airventilation intakes.Gas detectors GS20HCA/HCB (ventilation intake of fire and freshwater pumpstations) operate at very high levels (60% of the LEL), remaining operational untilcutting out. Gas detectors GS52HCA/HCB (ventilation intake of PP-BE column)operate at high level

HAZOPINVESTIGATIONINVESTIGATION

FAULT IN RISERDate:Participants of the HAZOPCoordinator of the HAZOP simplified:

1 Description of scenario according to Commission Inquiry

2 Physically possible?If so, how?

3 Necessary contributory factors4 Scenario indicators before the event

(verifiable)5 Defective safety features6 Liberation rate7 Possible ignition source8 Possible damage caused by the event9 Scenario indicators after the event

(verifiable)10 Intervention11 Probability evaluation of the scenario12 Others

Stability AnalysisINVESTIGATIONINVESTIGATION

Dispersion of Gases and Explosion Analysis

Gas concentration in column(Cross Section)

Explosion due to excessive pressure


Visit to sister platform Jack Bates

Jack Bates built according to the same Friede & Goldman project

Water service pipes and ventilation shafts on the 4th level


Purpose created diagrams

Damaged Zones


Event Final/Origin Type

* March 15 2001 00:22:54 ALARM/ALARM UNACK_ALMSmoke detector activated, located in the column, elevation 28956 (DE-5400-855-AMK-223)* March 15 2001 00:24:14 NORMA/ALARM ACK_RTN Smoke detector returns to normal

*March 15 2001 00:25:33 ALARM/ALARM UNACK_ALMSmoke detector activated again*March 15 2001 00:26:12 NORMAL/ALARM ACK_RTNSmoke detector returns to normal*March 15 2001 00:40:19 ALARM/ALARM UNACK_ALMSmoke detector activated again

Gas detector and their logic

Gas detector registers and damperactivity

Purpose created diagrams

INVESTIGATIONINVESTIGATIONTITLE: VENTILATION SYSTEM – FIRE ZONE 4CAUSE AND EFFECT ANALYSIS

Audit of Management Safety SystemINVESTIGAÇÃOINVESTIGAÇÃO

FLUTUADOR

COLUNA

MAIN DECK

SECOND DECK

STABILITY BOX

STARBOARD AFT COLUMN

PONTOON

COLUMN

MAIN DECK

SECOND DECK

STABILITY BOX

FAIR LEARD BOX

SECOND LEVEL

FOURTH

LEVEL

THIRD LEVEL

QUINTO PISO

SEA WATER OUTLET PIPE

SECOND DECK

TANK TOP

PONTOON

SEAWATER PUMP

FOURTH LEVEL

MAIN DECK

TANK TOP

EXHAUST SHAFT

THIRD DECK

SECOND DECK

VENTILATION SHAFTS

WASTE OIL TANK

FOURTH LEVEL

THIRD LEVEL

TANK TOP

EMERGENCY DRAIN STORAGE TANK

SEA WATER OUTLET PIPE

11stst Event:Event:Rupture of the Emergency Drain Storage Tank in the starboard aftRupture of the Emergency Drain Storage Tank in the starboard aft columncolumn

Accidental entry of hydrocarbons into the tank to be followed by waterExcessive internal pressure and rupture of the tankImpact felt at 00:22 h on March 15 2001Damage to equipment, pipes and electrical and electronic installations on the 4th

levelFlooding by water and oil with gas saturation on 4th levelPlatform lists 2 degrees in 5 minutesLoss of pressure in the firefighting network systemPlatform in ESD modeEmergency Firefighting Service goes to area of the occurrence

EventsEventsof of the Accident on Platformthe Accident on Platform PP--3636

EventsEventsof of the Accident onthe Accident on PlatformPlatform PP--3636

ATMOSPHERIC VENT

PRODUCTION HEADER

OPEN VALVE

CLOSED VALVE

SEMI-OPEN VALVE

CAISSON VALVE

HEADER VALVE

STARBOARD EMERGENCY DRAIN TANK

RACQUET

PORT EMERGENCY DRAIN TANK

KEY:

RACQUETS


22ndnd Event:Event:Explosion, damage, impact and death of the firefighting crewExplosion, damage, impact and death of the firefighting crew

Gas rises from the 4th level and reaches the upper platform levels to produce an explosive mixtureAn ignition source provokes an explosion of the gas mixtureA strong explosion occurs in the area of the starboard aft columnThis explosion occurs in the area where 11 members of the Firefighting Service are locatedShock waves and heat of the explosion severely damage the structures, equipment and accessories on the upper levels of the starboard aft areaAttempts to rescue the wounded (1 firefighter rescued, but dies one week later )Difficulties in maintaining platform stabilityEvacuation begins 01:45hPlatform is abandoned at 06:00h


33rdrd Event:Event:Flooding of void spaces and loss of the platformFlooding of void spaces and loss of the platform

Flooding of the 4th level of the starboard aft column due to the rupture of the DST, of the sea water line and the activating mechanism of the seawater pumps

Flooding of the pumping stations, of the propellers and the the water injection area through the ventilation shaft

Initial flooding of the 26S tank and the void space 61S through open inspection doors

Entry of sea water occurred through the sea chest which remained open (Fail-Set Valves)

Progressive flooding begins through the chain lockers, pontoon tanks, void spaces of the starboard aft column and deck; greater list

Final list and loss of the platform

ResultsResultsof of the Stability Analysisthe Stability Analysis

The flooding of the interconnected compartments caused the platform to sink and incline by more than 16 degrees at about 8:15h on March 15 200, sufficient to submerge the openings of the chain lockers, a situation which exceeded the structure’s maximum projected damage levels. This initiated the process of progressive flooding which ended in the sinking of the platform.

Opening of the chain locker

ResultsResultsof of the Stability Analysisthe Stability Analysis

HypothesesHypotheses

HYPOTHESES INVESTIGATED, EVALUATED and REJECTED FOR 1st and 2nd

EVENTS

SINCE NO OBVIOUS CAUSES WERE IDENTIFIED,VARIOUS SCENARIOS WERE ANALYZED

•EXPLOSION CAUSED BY BLOCKAGE

• SABOTAGE• MISALIGNED PIPING• MAINTENANCE SERVICES• COLLISION• CARGO HANDLING• DIESEL OIL SYSTEM

HYPOTHESES REJECTED DUE TO LACK OF EVIDENCE FOR SUCH IN THE 1ST and 2nd EVENTS

HYPOTHESESHYPOTHESES

• EXPLOSION CAUSED BY BLOCKAGE

• SABOTAGE

• MISALIGNED PIPING

• MAINTENANCE SERVICES

• COLLISION

• CARGO HANDLING

• DIESEL OIL SYSTEM

ConclusionsConclusions

The conclusions reached herein are based on the records of the Fire and Gas and Emergency Shut Down systems, documentation recovered from the platform and from existing Petrobras records.

Specific studies were made to give due technical support to the hypotheses established.

However, it is important to note that with the loss of P-36, there was no way of physically proving these hypotheses.


On the basis of the available information, the commission concluded that the most probable hypothesis for the sequence of events was:

Excessive pressure in the Starboard Emergency Drain Tank (EDT) due to a mixture of water, oil and gas, which caused a mechanical rupture thus leaking the EDT fluids into the 4th level area of the column.

The rupture of the Emergency Drain Tank caused damage to various items of equipment and installations in the column, principally the rupture of the sea water service pipe, thus initiating the flooding of this compartment, and released sufficient gas to fill the entire void space on the 4th level as well as other areas of the platform.

As to the accident


After 17 minutes, dispersed gas - in contact with an ignition source - caught fire, causing a major explosion in the area where the firefighting crew was located and also resulting in serious physical damage to the platform.

After unsuccessful attempts to stabilize the unit, the platform’s increasing inclination – reflecting continuous flooding – resulted in the chain lockers and the vent tubes of the buoyancy tanks reaching sea water level causing progressive flooding, culminating in the loss of the platform.

As to the accident


As to the causes that brought about the accident

As with every major accident, that of P-36 did not occur due to one single cause but was provoked by a series of factors.


Below are listed some of the probable causes of the accident:

The unexpected flow through the entry valve of the starboard EDT associated with the blocking of the vent and the racket absence in the entry valve, thus causing excessive pressure and rupture of the EDT;Alignment of the port EDT to the production header instead of to the Production Caisson, thus permitting the entry of hydrocarbons into the starboard EDT;Delay in activation of the drainage pump of the port EDT, allowing a reverse flow of hydrocarbons for approximately an hour;



Failure of the activators to close the sealed ventilation dampers permitting leakage through to the sealed habitable compartments of the column and pontoon;

Opening of the 26S tank and the 61S void space for inspection without following the procedure which established contingency measures, thereby increasing the volume subject to flooding;

Existence of two seawater pumps out of action for repair without contingency measures for substitution, reducing the scope to act in case of emergencies;

Deficient procedures and training to deal with emergency situations for controlling stability and ballast.


RecommendationsRecommendations

To require the E&P analyze the complete range of the problems cited and implement an Operational Excellence Program in the Marine Production Units.

In spite of being an oil industry practice, the Commission recommends that in future projects a management decision be taken not to use tanks or receptacles in columns or pontoons which are linked to processing activities. For those existing units with receptacles or tanks located in columns or pontoons and linked to processing activities, we recommend that the E&P carries out a reanalysis of its projects as to operational risk.

Adopt mechanisms for monitoring, evaluation and the dissemination of the execution of actions herein proposed.

AreasAreasindicated indicated for for improvementimprovement

During the course of the work of the Inquiry Commission areas were identified with room for improvement. While not directly linked to the accident, these areas need to be examined and included in the implementation of the Operational Excellence Program for the Marine Production Units.

AreasAreasindicatedindicatedfor for improvementimprovement

To improve the definition of responsibilities as they relate to the operation, maintenance and supervision of areas of production, platform infrastructure and control of stability.– Examples: Supervision/operation of equipment facilities linked to the

processing activities (Waste Oil Tank, EDT);operation of ballast and infrastructural equipment (Sea Water Pump)

Review supervisors’ functions to reduce their bureaucratic activities and to concentrate their focus on operating activities, such as: operations in progress; non-routine adjustments; restrictions caused by warning or safety features; operational procedures, the complexity or risk of which requires their personal intervention.


Review the size and upgrade the skills of the Company platform crew in accordance with the complexity of the installations and the operations involved, the use of new technologies, the strategic importance of the installations to the Company’s business and avoid the accumulation of functions, thus assuring the presence of the full supervisory team on board.


Restructure and establish priorities for maintenance activities to ensure:– Compliance with preventive/scheduled maintenance

programs;– Reestablishment of maintenance engineering;– Conclusion and effective implementation of the RAST;– Elimination of late preventive maintenance routines;– Re-dimensioning of Company teams; – Ensure the necessary qualification levels for outsourced

teams especially in relation to mechanical and instrumentation aspects.


Systematize the process for the management of the changes to ensure that the project alterations are only implemented after the completion of risk analysis, up-dating of documentation, the approval from the appropriate authorities and training of the operating and maintenance team. For this it is necessary, among other measures: – To train the teams in the techniques of identification,

evaluation and control of risk situations;– To systematize the identification of potential risks in the

areas of Safety, the Environment and Health (SMS) including major accident and total loss risks.


To upgrade the Emergency Procedures and Plans in relation to, among other aspects, the following topics:– The firefighting crew to go directly to the location of the

occurrence;– Compartments to remain sealed in case of flooding;– Means to be used in the case of evacuation (cranes x

lifeboats);– Use of portable gas detectors for continuous

monitoring with sound and visual alarms;– Use of communication systems during emergencies.


To invest in technical training involving control of stability and ballast, promoting retraining and training in emergency control. The training to be tailor made for each unit.To guarantee that the units’ documentation is up-to-date and available both on-board and also with onshore management.To put into practice a system of copying and recovery of key information before final evacuation through implementation of features similar to those used in the aeronautical industry, such as the black box or removable HD with the object of recovering operating information in the event of emergency.


To reevaluate project requirements and the E&P safety philosophy to include:– More rigorous classification of areas;– Restriction in the use of alternative requirements for

stabilizing in the event of damage;– Restriction on the use of vital common systems by

floating units (refrigeration x ballast x firefighting);– Use or not of FAIL-SET valves in ballast system;– The number of ballast pumps interlinked in the case of

emergency;– Prioritize alarms to avoid excessive information in the

control room, especially during emergency situations.

“ Every serious accident is unique, since each one includes various elements which only occur once.”

Gerard Mendel, in “Industrial Accidents, the cost of silence”, MichelLlory, MultiMais Editorial, 1999

Petrobras P36 Sinking Report

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Transcript of Petrobras P36 Sinking Report