Annual DP Trials for DP Mobile Offshore Drilling Units

lickforkabsorbingOil and Offshore

Nov 8, 2013 (3 years and 7 months ago)

321 views








Guidelines for
Annual DP Trials for DP
Mobile Offshore Drilling Units

www.imca-int.com


IMCA M 191

February 2008


International Marine
Contractors Association
www.imca-int.com
AB







AB

The International Marine Contractors Association
(IMCA) is the international trade association
representing offshore, marine and underwater
engineering companies.

IMCA promotes improvements in quality, health, safety,
environmental and technical standards through the publication
of information notes, codes of practice and by other
appropriate means.

Members are self-regulating through the adoption of IMCA
guidelines as appropriate. They commit to act as responsible
members by following relevant guidelines and being willing to be
audited against compliance with them by their clients.

There are two core activities that relate to all members:

Safety, Environment & Legislation

Training, Certification & Personnel Competence

The Association is organised through four distinct divisions,
each covering a specific area of members’ interests: Diving,
Marine, Offshore Survey, Remote Systems & ROV.

There are also four regional sections which facilitate work on
issues affecting members in their local geographic area –
Americas Deepwater, Asia-Pacific, Europe & Africa and Middle
East & India.


IMCA M 191


This guidance was produced for IMCA under the direction of its
Marine Division Management Committee.

www.imca-int.com/marine



The information contained herein is given for guidance only and endeavours to
reflect best industry practice. For the avoidance of doubt no legal liability shall
attach to any guidance and/or recommendation and/or statement herein contained.

Guidelines for Annual DP Trials for
DP Mobile Offshore Drilling Units

IMCA M 191 – February 2008



1 Introduction...........................................................................................................1
1.1

Scope....................................................................................................................................................................1

1.2

Background.........................................................................................................................................................1

2 Objectives...............................................................................................................2
2.1

Primary Objectives............................................................................................................................................2

2.2

Secondary Objectives.......................................................................................................................................2

2.3

Additional Objectives........................................................................................................................................2

3 Other Guidelines...................................................................................................3
4 DP Trials for MODUs............................................................................................4
4.1

Annual Trials Programme................................................................................................................................4

4.2

Arrangements for Annual Trials Programme...............................................................................................5

4.3

Annual Verification............................................................................................................................................5



IMCA M 191 1
1 Introduction
1.1 Scope
These guidelines provide advice on undertaking the annual dynamic positioning (DP) trials for DP
mobile offshore drilling units (MODUs) on a continual basis throughout the year.
The purpose of the trial programme is to improve safety and performance by reducing risk. These
guidelines propose a method of achieving these goals by carefully managed testing of all important
systems and components of a DP system to ensure that the DP system is maintained in good working
order. Particular focus is placed on verifying the conditions from the failure modes and effects analysis
(FMEA) that are difficult or impossible to verify by any other method. The trial programme may be
conducted on an incremental basis throughout the year as opportunities arise but needs to be
completed within a twelve month period.
The guidelines are designed to provide a common approach for DP MODU annual trials.
1.2 Background
In the 1980s DP systems onboard vessels were tested many times during a year and the time required
for the frequent repetitious testing events was costly and inconvenient for both vessel owners and
their clients. In addition, the frequent testing raised the risk of equipment damage.
In 1991 vessel owner representatives met with oil company and government representatives to
discuss and rationalise the auditing and testing of dynamically positioned vessels. This resulted in the
DPVOA guideline 112 UKOOA Part 2 which was published in 1992
1
. In 1993 the rationalisation
process continued and was enhanced with the production of International Maritime Organization
(IMO) Maritime Safety Committee (MSC) circular 645 which was adopted in 1994. This IMO circular
requires annual testing of all important systems and components of a DP system to ensure that it is
maintained in good working order.
The use of the traditional annual DP trial, where all of the DP tests are carried out at a specific time
once a year, has not been widely accepted and taken up for DP MODUs because their continuous
work programmes do not usually provide suitable non-operational periods that can be used for such
an approach. Therefore, these guidelines have been produced setting out a reasonable way to
perform the trials programme incrementally throughout the year as opportunities arise, while ensuring
that the total scope of the trials programme is accomplished within a twelve month period.


1
DPVOA guidance note 112 UKOOA Part 2 – ‘Guidelines for auditing vessels with dynamic positioning systems’ is to be superseded by
guidance document IMCA M 190 – ‘Annual trials for DP vessels’, expected to be published in early 2008.
2 Objectives
2.1 Primary Objectives
The primary objective of the annual trials programme is to improve the safety of DP MODU
operations by:
♦ encouraging MODU vessel owners to carry out detailed, auditable tests as part of an annual trials
programme;
♦ verifying that the DP system is in good working order and that the FMEA remains valid.
2.2 Secondary Objectives
The secondary objectives of the annual trials programme are:
♦ to provide a common standard approach for the auditing and accepting of DP vessels by client
companies that adequately discharges their duty of care to the satisfaction of their regulatory
bodies;
♦ to make the DP testing and acceptance process more efficient and thus save the industry time and
unnecessary cost.
2.3 Additional Objectives
Additional objectives of the annual trials programme are:
♦ to give failure response training and experience to DP personnel;
♦ to document the trials results;
♦ to demonstrate good management of change.
2 IMCA M 191

IMCA M 191 3
3 Other Guidelines
These guidelines do not replace IMCA M 190
2
which sets out guidelines for undertaking the full annual trial
programme at a specific time once a year for other types of DP vessels, as described in IMCA M 103 –
‘Guidelines for the design and operation of dynamically positioned vessels’. Such a programme is applicable to other
types of DP vessels.
Guidance document IMCA M 182 – ‘International guidelines for the safe operation of dynamically positioned offshore
supply vessels’ – sets out specific arrangements for annual DP trials for offshore supply vessels.


2
DPVOA guidance note 112 UKOOA Part 2 – ‘Guidelines for auditing vessels with dynamic positioning systems’ is to be superseded by
guidance document IMCA M 190 – ‘Annual trials for DP vessels’, expected to be published in early 2008.
4 DP Trials for MODUs
4.1 Annual Trials Programme
The purpose of the DP trials is to improve the DP system safety and performance by testing faults and
failure conditions important to DP safety to prove the ability of the vessel to keep position after single
point failures associated with the IMO equipment class and to verify the FMEA requirements. When
faults identified during the year on other similar DP MODUs are determined to be feasible on the
vessel then additional tests should be incorporated in the trials programme.
The annual trials programme should be undertaken by appropriate personnel onboard the vessel, but
should be witnessed and signed off by the vessel master or offshore installation manager (OIM).
The use of a third party witness, either an in-house independent specialist such as the vessel owner’s
fleet DP superintendent or a competent independent third party consultant, is optional and should be
at the discretion of the vessel owner or at the request of the client. Any such witness needs to be
familiar with the type of vessel and its annual trials programme.
The annual trials for a MODU should have a defined testing programme. This should contain testing
of single failure items based on the vessel-specific FMEA but may also contain non-FMEA items such as:
♦ performance verification testing of perishable items, such as power plant load acceptance capacity
and capacity of battery/uninterruptible power supplies;
♦ DP operational items, such as blackout recovery drills;
♦ verification and exercise of operating parameters or limits not normally demonstrated in routine
operations, such as power limits.
The setup of the DP system when undertaking the various tests which make up the annual trials
programme should reflect the normal setup used by the MODU. Each test should reflect the safest
way to operate the vessel in the water depth and environmental conditions present at the time of the
test. The MODU owner’s DP fleet vessel superintendent/in-house independent specialist should
confirm that the proposed tests are consistent with the assumptions of the FMEA.
Documentation describing all the tests to be undertaken as part of the annual trials programme and
expected results should be available on the MODU. The results of previous tests undertaken during
trials programmes should also be available. Blank sheets for completion of each test should be
provided. Vessel crews are expected to be fully conversant with the trials programme and able to
carry out all the tests.
If the work of the DP vessel includes several DP modes then every effort should be made to test these
modes and the failures associated with them.
Tests that are essential to be included during the annual trials programme include the following:
♦ All prime movers to full power long enough for temperatures to stabilise or for a minimum of
15 minutes, with tests to be allowed in pairs or groups;
♦ All thrusters and propellers to full power long enough for temperatures to stabilise, or for a
minimum of 15 minutes with tests to be allowed in pairs or groups whether or not on DP.
Thruster azimuth rates and ramp rates should be verified;
♦ Demonstration of the single worst case failures;

Demonstration of open and closed bus power management system(s) for power limit, increase of
online power capacity and power restoration (black out recovery);
♦ Network failures for DP and integrated control systems.
The specific design of the annual trials programme should be the responsibility of the vessel owner
who should include:
♦ the FMEA report;
♦ recent experience in the industry with respect to DP incidents;
♦ system modifications since the last trials programme report.
Client representatives may request additional pertinent tests to be included in the trials programme.
4 IMCA M 191

IMCA M 191 5
The vessel master/offshore installation manager (OIM) and any other witnesses to the tests making up
the annual trials programme need to be familiar with:
♦ the FMEA report;
♦ the last annual trials programme report;
♦ the proposed content of the forthcoming annual trials programme;
♦ recent developments in the industry with respect to DP incidents; and
♦ system modifications since last annual trials.
The vessel master/OIM may consider the planned maintenance status report available prior to any
tests being performed so that this can be taken into account during the tests. The vessel master/OIM
should also have access to any vendor visit reports so that tests may be adjusted to prove that
problems experienced relevant to DP were corrected.
For each test making up the annual trials programme, the following should be recorded:
1 Purpose (what is planned to be demonstrated);
2 Method (how it is to be carried out);
3 Results expected – locally and for DP;
4 Results found;
5 Comments;
6 Date and signature of vessel master/OIM witnessing the test.
Completion of each test should be recorded in a table/log showing the dates when each test was
conducted.
4.2 Arrangements for Annual Trials Programme
These guidelines set out the requirement for DP MODUs to undertake a DP trials programme on an
annual basis.
Due to the nature of DP drilling work, with a DP MODU often connected to an exploration or
production well for extended periods of time, it is not always possible to set aside sufficient time
during a year to undertake the full annual trials programme in one go. Therefore, provided that the
total scope of the tests which make up the annual trials programme is covered, the tests can be
undertaken incrementally throughout the year as the opportunities arise.
If the opportunity to undertake the full annual trials programme at one time presents itself, for
example after dry-dock, this is preferred because of the ability to verify integrity of the DP systems
after maintenance, repair or modification.
If the full annual trials programme is required prior to a contract, then the complete programme
should be carried out. However, the incremental tests making up the annual trials programme carried
out over the preceding year may be able to satisfy this requirement.
4.3 Annual Verification
Each year an annual verification exercise should be undertaken by the vessel owner’s fleet DP
superintendent/in-house independent specialist or other senior corporate official to review and accept
that the various tests identified in the annual trials programme have been completed and that an
appropriate report is provided for each test. It may be appropriate for the vessel owner to mobilise a
competent independent third party consultant to undertake this verification and to inform clients, for
whom the MODU is expected to work during the following year, so that they may review the annual
trials programme results if they so wish.
Tests relating to any modifications made to the vessel during the year should be included in the annual
verification and should be added to the annual trials programme for future years.
The execution of the annual verification should be decided to best fit into planned operations but
should be carried out within three months of completion of all the tests identified in the annual trials
programme.