Lessons Learned . . . or Not Kevin Duffin, Kevin Smith Maritime - - PowerPoint PPT Presentation

DYNAMIC POSITIONING CONFERENCE

OCTOBER 9‐11, 2017

RISK

Lessons Learned . . . or Not

Kevin Duffin, Kevin Smith Maritime Assurance & Consulting

10th October 2017

Lessons Learned… or Not

Background

• Old guidance revised

– IMCA M103, Feb. 2017 – IMCA M166, Apr. 2016 – IMCA M190, Mar. 2017 – IMCA M245, Aug. 2017

• New guidance created

– TECHOP_GEN_01, Sep. 2012 – TECHOP_ODP_01_(D), Oct. 2013 – TECHOP_ODP_08_(O), Sep. 2014 – TECHOP_ODP_11_(D), May 2015 – TECHOP_ODP_13_(D), Sep. 2016

• Workshops and Seminars

– MTS Europe DP Workshop (2017) – IMCA - Live Short Circuit Testing (2014) – Annual MTS and IMCA conferences

• Guidance produced to make DP operations

safer, surveys more objective and to improve consistency across the industry

• MAC’s experience would suggest the same

mistakes are still being made

• Here, we present some of the more critical

issues from recent trials and assurance work…

Part I – Interpretation of Trials Requirements

Annual DP Test

Introduction – DP Trials throughout Vessel Lifetime

Initial Survey

Supplementary Trials Revised Annual DP Test Changes to DP System?

Complete DP Test

5th year FMEA review (latest guidance, drawings review, industry lessons learned) may require that the FMEA be re‐written and so cycle starts again

Year 0 Year 1 Year 5 Y N

FMEA complete

Year 1 Test Matrix

IMO MSC.1/Circ.1580, 5.1.1.1: “An initial survey which should include a complete survey of the DP system and FMEA proving trials for DP Classes 2 and 3 to ensure full compliance with the applicable parts of the

• guidelines. Furthermore it should include a complete test of all systems

and components and the ability to keep position after single failures associated with the assigned equipment class.” IMO MSC.1/Circ.1580, 5.1.1.3:“The annual survey should ensure that the DP system has been maintained in accordance with applicable parts of the guidelines and is in good working order. The annual test of all important systems and components should be carried out to document the ability of the DP vessel to keep position after single failures associated with the assigned equipment class and validate the FMEA and Operations Manual.”

Year 2 Test Matrix Year 3 Test Matrix Year 4 Test Matrix Annual DP Test

IMCA M190, 4.11:“… it is accepted that there may be some components of the DP system which, provided their reliability has been proven throughout the year or they do not provide critical redundancy, may after review be subject to a rolling programme of testing such that they are not tested every year.”

FMEA Proving Trials

FMEA Verification Complete DP Test

Desktop FMEA

Rolling Annual DP Test

IMO MSC.1/Circ.1580, 5.1.1.2: “periodical testing at intervals not exceeding five years to ensure full compliance with the applicable parts of the Guidelines. A complete test should be carried out as required in paragraph 5.1.1.1”.

Interpretation of Initial / 5-Year Survey Requirements

Year 1

Annual DP Test

Supplementary Trials Revised Annual DP Test Changes to DP System?

Complete DP Test

Year 0 Year 5 Y N

FMEA complete

Year 1 Test Matrix Year 2 Test Matrix Year 3 Test Matrix Year 4 Test Matrix Annual DP Test

Desktop FMEA

Rolling Annual DP Test Initial Survey

FMEA Proving Trials

FMEA Verification Complete DP Test

• In the last year MAC have 3 examples of this process being challenged, specifically the

interpretation of 5-yearly periodical survey requirements

Interpretation of Initial / 5-Year Survey Requirements

• Latest revision of MSC.1/Circ.1580 is more explicit and so latest revision of IMCA M190 is

more explicit.

• Guidance that precedes this year is not so explicit.
• This leads to different interpretations of what constitutes a 5-yearly periodical survey /

trials programme.

TECHOP_ODP_01_(D)_(FMEA TESTING)_Ver2 October 2013: “Phase 1 ‐ Proving Trials: …Once it has been established that all the necessary attributes are present and they provide the DP systems with fault tolerance then this aspect of testing need not be repeated for another five years according to existing guidance.”. IMCA M190 March 2017 (interpretation of IMO): “The question often arises of when or if the FMEA proving trials should be repeated. There is sometimes a belief that there is a requirement to carry out FMEA proving trials every five years. This belief perhaps comes from interpretation of the classification societies’ requirement to carry out more in‐depth surveys on a five‐yearly basis. Generally speaking, the purpose of the classification society five‐yearly survey, as well as functionally testing the DP system, is to verify the level of redundancy with reference to defined single failures that was established by the FMEA (and proven by trials). This is different from redoing the FMEA proving trials programme”. IMCA M190 interpretation of IMCA M103 – “The DP annual trials programme should be based on the vessel’s DP FMEA proving trials, cover a period of more than one year and should be repeated after five years”. MSC 645 – “Initial survey which should include a complete survey of the DP‐system to ensure full compliance with the applicable parts of the

• guidelines. Further it includes a complete test of all systems and

components and the ability to keep position after single failures associated with the assigned equipment class”.

Interpretation of Annual Trials Requirements

Year 1 Test Matrix Year 2 Test Matrix Year 3 Test Matrix Year 4 Test Matrix Annual DP Test Annual DP Test Initial Survey

Supplementary Trials Revised Annual DP Test Changes to DP System?

Complete DP Test

Year 0 Year 1 Year 5 Y N

FMEA complete

FMEA Verification Complete DP Test

Desktop FMEA

Rolling Annual DP Test

Interpretation of Annual Trials Requirements

• Pressure from Industry to reduce annual test scopes

– Planned maintenance evidence used in lieu of conducting some test steps

• Often the planned maintenance programme is not aligned to the test requirements

– Redundancy group tests

• “Can we test only one per year?”

– Net throughput / storm testing

• Requires manufacturer support

– Insufficient position references tested to demonstrate compliance with Class rules and industry guidance

• Testing relative position references can be difficult

IMCA M103, Rev. 2 June 2016: “The annual DP trial should test all functions on which the redundancy concept depends, including network testing, blackout recovery plans and ESD functions”. IMCA M103, Rev. 2 April 2016: “The annual DP trial should test all functions on which the redundancy concept depends, including network testing (data storms and throughput test), blackout recovery plans and ESD functions”. IMCA M190, Rev. 1 March 2017: “Tests that are essential to be included during the annual trials include the following:

• network failures for DP and integrated control systems”.

MTS Annual Trials Gap Analysis September 2014: “If both networks are not capable of carrying all the traffic the vessel will lose position if one network fails”. "Network storms are a potential common mode failure capable of causing a drift off. All modern networks are fitted with protection against this type of failure. This protection must be checked periodically to confirm it is operational and that alarms to indicate that it is

• perating are working”.

Part II – Common Findings from Trials and Assurance Reviews

Legacy Issues and Understanding Fail Safe

• Thrusters failing to uncontrolled rotation.
• Witnessed on a DP 3 dive vessel, 2 x DP 3 drilling vessels, 2 x DP 3 semi-submersibles

and a DP 2 pipe-laying vessel

Angle RPM Angle Angle Angle Angle Angle Angle Angle Angle

• Loss of azimuth command signal results in rpm freeze and azimuth rotation to 0° (ahead)

= undesired thrust vector!

IMO MSC.1/Circ.1580: “Failure of a thruster system including pitch, azimuth and/or speed control, should not cause an increase in thrust magnitude or change in thrust direction”. IMCA M190: “For vessels with variable speed thrusters of proven reliability, it may be acceptable to carry out the control loop wire break tests on a rolling programme where all tests are carried out over a five‐year period. Controllable pitch propellers should be tested annually”.

Legacy Issues – Automatic Changeovers and Transfer of Fault

PS 1 PS 2 PS 3

G M VFD G G G M VFD M VFD M VFD M VFD

Auto changeover allows azimuth thruster to be restored quickly after failure of PS supply

• Witnessed on a DP 3 pipe-lay vessel

T1 T2 T3 T4 T5

CB A CB B

Legacy Issues – Automatic Changeovers and Transfer of Fault

PS 1 PS 2 PS 3

G M VFD G G G M VFD M VFD M VFD M VFD

I>> I>> I>> I>> I>> I>> I>> I>> I>>

Blocking signal allows for local isolation of fault

EF U< I>> U< U< EF U< I>>

Hardwire interlock prevents both PS 3 feeder breakers being closed Dedicated protection relays for U<, EF, I>> T1 T2 T3 T4 T5

CB A CB B

Legacy Issues – Automatic Changeovers and Transfer of Fault

PS 1 PS 2 PS 3

M VFD G G M VFD M VFD M VFD M VFD

PS 1

G G

• 1. Dead bus condition on PS1

 

• 2. Healthy bus condition on PS2



• 3. PS1 ‐ PS2 CBs open
• 4. PS1 – PS3 CB open



T1 T2 T3 T4 T5

CB A CB B

Legacy Issues – Automatic Changeovers and Transfer of Fault

PS 1 PS 2 PS 3

M VFD G G M VFD M VFD M VFD M VFD

PS 1

G G

• 1. Dead bus condition on PS1

 

• 2. Healthy bus condition on PS2



• 3. PS1 ‐ PS2 CBs open
• 4. PS1 – PS3 CB open



I>> I>> I>> I>> I>>

!

U< U< U< I>> I>> I>> U< U<

A single failure in combination with a hidden failure of the CB could blackout the vessel!

T1 T2 T3 T4 T5

CB A CB B

Legacy Issues – UPS Configurations

• Witnessed on 2 x DP 3 pipe-lay vessels this year
• A configuration error that can defeat the redundancy concept

– UPS bypass alarms are a requirement under certain Class rules

Redundancy Group PS Redundancy Group SB

Main Bypass

PS DP UPS

XX

Legacy Issues – Control Voltage Cross Connections

• Witnessed on a DP 3 pipe-lay vessel this year

Control & relays SWBD PS Breaker Motors SWBD PS Control & relays SWBD SB Breaker Motors SWBD SB

PS Redundancy Group SB Redundancy Group Class insisted fuse links be removed to protect redundancy 110Vdc control voltage PS 110Vdc control voltage SB Consumers introduced cross connections regardless

Loss of PS switchboard! No alarm!

Backups of backups were popular on older vessels

Legacy Issues – Closed Bus System Testing

PS 1 PS 2 PS 3

G M VFD G G G M VFD M VFD M VFD M VFD

Load 20% Load 0% Load 20% Load 20% Load 100% Load ‐25% Load ‐25%

Crew fearful of conducting “destructive tests”.

• Common occurrence in our DP PSV vessel assurance work

A single failure can result in total blackout!

Legacy Issues – DP Control System Redundancy

• Witnessed on a DP 3 pipe-lay vessel and a DP 3 dive vessel this year
• Complex survey configurations directly affecting DP system redundancy

Cha Change suppl ge supply y to to Survey U rvey UPS Disabl Disable IALA, IALA, sin single le ante antenn nna and and use new use new subscription c cription corrections rrections for bot for both F8 F8 – Surve urvey rack backup kup suppl upply F9 F9 – Surve urvey coff

• ffee machin

achine F10 F10 – Crew Crew movi movie server erver

Gyr Gyro 3 3 to HP to HPR VRS VRS 3 3 to HP HPR

Conclusions

• All cases presented are representative of issues already well understood within the DP

community – Current industry climate is applying pressure to DP vessel assurance. – Many of the issues can be attributed to naivety or lack of appreciation for guidance and industry standards. – Ambiguity in the guidance can also be a factor.

• MAC is one of many DP consultancies

– Are other DP practitioners seeing the same legacy issues? – What is the scale of the problem globally? – Are lessons being learned..?

• How can we move forward with trials programmes that maintain standards and meet

everyone’s expectations?

Thanks for your time

Any questions?