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					TITLE SafeShip sets the standard

DECKHEAD IT is becoming an increasingly important part of class, and
ABS is at the forefront of this development. David Robinson of ABS
explains the classification society’s comprehensive and innovative
SafeShip programme
In the marine and offshore industries, it is well known that the primary concern of a
classification society is to develop, and subsequently check compliance with Rules for
the design, construction and maintenance of marine structures. However, over the last
decade or so, the development of the Rules themselves and methods for checking
continued compliance, have changed dramatically due to the exponential growth in
computing power, database technology, communication capabilities and client’s
expectations of such technologies. Within ABS, we have seen the emergence of the
Dynamic Loading Approach, a first principles or direct calculation approach to the
loading and structural response of a ship, SafeHull, a first principles approach to
structural design requirements and SafeNet, an information management system for
survey planning and execution.

At first, these were individual and unique developments covering different phases of a
ship’s life, but now they have been integrated into a programme called SafeShip to
produce a suite of products and procedures covering the whole life cycle care for
tankers, bulk carriers and containerships.

Before describing the components of SafeShip in detail, it is worth defining what it is
in general terms. It is an integrated programme being offered to all clients of ABS
with SafeHull vessels, at no cost, for them to take advantage of tools and services
develop by ABS for the life cycle care of such ships. Many of the applications
(software) used within SafeShip have been developed at a very high cost, but ABS
feels very strongly that such capabilities must be freely available in order that the
much higher level of information is used to make informed decisions regarding
surveys, maintenance and repairs.

Because it is based on SafeHull, the service concentrates on hull structures at this
stage, but the philosophy of holding and using electronic data is common to all
aspects of a ship and its operation. It will, therefore, be expanded to cover new areas
such as machinery and systems and human factors in the future.

SafeShip consists of four parts, each corresponding to different stages of a ship’s
lifetime, from design through to the last survey: SafeHull, obviously in the design
assessment phase, but also later in the ship’s life for re-assessments; Hull
Construction Monitoring during the construction phase; Vessel Drawings Storage; and
Hull Maintenance during the operational phase.

CROSSHEAD SafeHull

SafeHull was introduced as a Rule requirement for tankers, bulk carriers and
containerships in 1993. This first principle approach revolutionised the design
assessment process by departing from the prescriptive empirical methods used


ABS SafeShip
previously. Apart from this fundamental difference, there are notable variations in the
design assessment process to point out. Firstly, the structure of the design is defined
to a very high level and is represented graphically. Secondly, software is used to
check input and output from the program, and most importantly, checks are
automatically made for all relevant failure criteria, with output clearly showing the
extent of compliance or non-compliance of the design with the Rules of the submitted
design.

The SafeHull system incorporates many of the technological developments that have
occurred previously, such as the estimation of dynamic loads using environmental
analysis and ‘strip theory’ and the resulting structural response using finite element
analysis. These techniques are now incorporated as mandatory rule requirements and
the resulting process is very different from designing a ship to comply with simple
prescriptive criteria, and herein lie enormous benefits when we need to look at fitness
for purpose or capability later in the ship’s life.

SafeHull is carried out in two phases, the first of which considers the adequacy of all
individual structural components against relevant failure modes, including fatigue,
and the second includes the evaluation by Finite Element Analysis of all the
interactions of the primary and secondary structures and the overall strength
assessment. Once a design complies with both of the two phases, output from
SafeHull will quantify all of the reserves of strength in either offered to required ratios
or diagrammatically using various methods of display. SafeHull thus gives the
builder, owner and ABS the ability to understand, in quantitative terms, the strengths
and weaknesses of a design.

During the process of ‘plan approval’, it is a requirement for ABS engineers to
identify any area classed as ‘sensitive’ or highly stressed so that appropriate
construction standards can be applied to such areas. This capability leads us to the
next component of SafeShip, namely Enhanced Hull Construction Monitoring
described below.

CROSSHEAD Enhanced Hull Construction Monitoring

The requirement for ABS engineers to highlight areas of higher stress and to pass this
information on to the new construction surveyors has been in place for some years, as
has the requirement to insist on higher construction standards from the shipyards.
What has changed, however, under the requirements of is the need for documentation
of the standards used and of any remedial corrective action taken when applying the
standards.

The new Enhanced Construction Monitoring Guide, which was published in June
2000, details the responsibilities and interaction of the ABS Hull Project Engineer, the
Shipyard and the ABS attending survey who all have a part in ensuring that structural
details subsequently perform according to design requirements.

Under this regime, it is the ABS Hull Project Engineer’s responsibility to identify
areas close to design limits or likely to be significantly affected by construction
standards; to approve the standards to be used by the shipyard for such areas; and to
provide technical support to the attending surveyor during construction.


ABS SafeShip
The Shipbuilder must document the following: areas of the ship’s structure which
require special attention and care, the construction measures taken to address these
areas, a corrective action plan for non-conformances, quality procedures and the
methods to be used and a structural inspection plan.

The ABS Attending Surveyor must review the shipbuilder’s structural inspection plan,
ensure that the prescribed standards for construction tolerances, welding control and
erection procedures are applied, ensure that any necessary corrective action is carried
out and issue a report and certificate.

CROSSHEAD SafeNet

SafeNet, a marine information management network developed by ABS, was first
introduced to shipowners in 1996 as a means for obtaining their survey status and
related marine information online. These were the first two modules of SafeNet to be
developed and distributed to all owners and were also the means whereby ABS
surveyors obtained a ship’s survey status before carrying out their surveys. In the
owner’s version of SafeNet, there is also a survey planning document capability as
required by ABS and IACS for Enhanced Survey Programme vessels.

Subsequently, SafeNet developed in two ways, firstly to embrace a vessel drawing
storage module plus a hull maintenance module, and secondly, to incorporate a whole
range of operational software modules available through the ABS Nautical Systems
company. The SafeNet modules incorporated in SafeShip are the Survey Status,
Marine Information, Vessel Drawings and Hull Maintenance modules. The Survey
Status and Marine Information modules essentially provide the owner with the
necessary information to plan upcoming surveys, whereas the Vessel Drawing and
Hull Maintenance modules are the tools for carrying out and keeping track of the
surveys, inspections, maintenance and repairs.

The vessel drawing module of SafeShip will provide the most frequently used
drawings on a CD, so that they may be more readily accessed either in the owner’s
office or on the ship. The application that will be provided with the CD will enable the
user to access any of the drawings or parts of a drawing, mark the drawing with notes
or instructions and print to any normal size for convenience of carrying on board.
The service can be expanded to include any number of drawings, calculations or
documentation, but such a service will be at a cost to the owner and will be available
through ABS Nautical Systems.

The drawings provided with SafeShip at no cost, include:
    General Arrangement, Midship section
    Scantling Profiles and decks (including hatch covers for bulk carriers,
       containerships and general cargo vessels),
    Shell expansion, Watertight and deep tank bulkheads, Capacity plan,
    Docking arrangements, Rudder arrangements, Steering gear,
    Machinery layout, Piping line diagrams, Electrical line diagrams,
    Propeller and shaft arrangements,
    Cargo oil systems, crude oil washing systems, IGS,


ABS SafeShip
       Remote and Automatic Control Systems,
       Safety Plan.

The drawings can be either in digital electronic format or in raster scan format
obtained from the scanning of a hard copy drawing, both of which can be stored and
accessed from the same CD.

CROSSHEAD SafeNet Hull Maintenance module

Although the SafeNet hull maintenance module is just one part of the SafeNet system,
it is a very important part because it is central to all classification activities concerning
the design, construction and maintenance of the hull structure. It has been developed
and enhanced over a period of some three years to become a product that uses the
most up-to-date electronic communication techniques to store, display, monitor and
predict structural condition from a classification society’s and owner’s perspective.

At the heart of SafeNet, and the hull maintenance module of SafeNet in particular, is a
database that contains a complete description of the ship’s form and hull structure in
electronic format. When the database is created, either by converting hard copy
drawings or using shipyard’s electronic drawings, it contains only the ‘as built’ data
describing the scantlings and arrangements that are the starting point for collecting
life cycle data. Subsequently, many forms of data associated with the drawings are
entered into the database in order to represent the precise condition of the ship at any
point in time. The following list of drawings and hull form data are used to establish
the initial and otherwise empty database:

           General Arrangement
           Capacity Plan
           Shell Expansion
           Midship Section
           Transverse Bulkhead
           Construction Profile
           Deck Plans
           Fore End Construction (Collision BHD fwd)
           Aft End Construction (After peak space)
           Cargo Hold Construction including Forward and After Cargo Hold
            Construction

In order to be able to track the condition of any component of the structure throughout
the entire life cycle of the vessel, including details of corrosion, thickness, damage
and subsequent repair, a complete description of plates and stiffener boundaries and
properties must be in the database; SafeHull Maintenance provides this level of
information. The purpose of having access to this kind of information is to be able to
assess capability at any point in time and also to be able to determine maintenance
strategies to prevent failures and any downtime associated with unscheduled repairs.

Data entry by the class society or by the owner is achieved through separate sessions
governed by rules covering editing and viewing rights that maintain agreed levels of




ABS SafeShip
confidentiality. This means that the database can be used by the owner to hold and
use information to which the class society will not have access.

The type of data that can be entered, viewed and analysed has been derived over time
and based on the needs of the two main user groups of class and operators and has
been confirmed and expanded through pilot studies with major shipowners. All input
into the database is date stamped so that subsequent viewing can be done for any
‘reference date’. No data is discarded.

Apart from the complete description of the ‘as built’ structure along with all
associated scantlings, the following main data entry categories are included in
SafeNet Hull Maintenance: thickness measurements, critical areas for inspection,
fractures, pitting, coating condition, damage areas, repair areas and recommendations,
plus any photographs, sketches or text associated with any of the input parameters.

The application allows for the simple entry of engineering analysis relating to highly
stressed areas and all survey data, thickness measurements and inspection findings,
directly onto the electronic definition of the structural item or compartment, with data
entered in ‘sessions’ covering a particular review, survey or inspection period.
Associated photographs or sketches are stored in the database as attributes of either a
structural component or a compartment. All data is date stamped for entry into the
database and no data is removed during the life of the ship as it is used to view the
condition at any point in time.

The predictive mode at present only relates to thickness determination, based either on
a curve fit to gauging values measured over time or from standard published corrosion
rates. Other output formats include thickness measurement reports (in IACS required
format) obtained automatically from gauging inputs, pitting data and
recommendations, coating condition data including precise area calculations, critical
areas for inspection, inspection plan timeline including outstanding inspections,
ability to search and view fractures, damages, repairs and areas of substantial
corrosion. After an area has been identified for repair, the program adds up all the
associated areas and weights to obtain estimates for repairs based on shipyard tables,
will produce a repair specification and include the associated diagrams.

CROSSHEAD SafeHull Re-analysis

In the same way that SafeHull determines the strengths and weaknesses of the design
prior to construction, so it can be used to do the same thing as the ship ages. This is
infinitely better than relying on prescriptive criteria to judge when structural
components have to be replaced, as SafeHull enables a re-examination of the
capability of the ‘as is’ condition to resist all the same failure modes that were
assessed during the design phase. This re-examination will be done first in
preparation for the second special survey using predicted thickness estimates with the
results being posted for viewing, by surveyors and operators into the Hull
Maintenance module. The predicted thicknesses will then be compared with the
actuals during the survey to see whether the prediction was accurate or not and
therefore whether any re-analysis is necessary. This information can then be used to
predict forward to the next special survey and if SafeHull predicts any area or failure
mode becoming a problem, the owner can elect to adopt an appropriate maintenance


ABS SafeShip
regime in order to prevent renewals. If used correctly, renewals can be drastically
reduced in later life.

Another benefit of using SafeHull, for actual and predicted conditions, is that more
rational renewals can be suggested based on remaining life criteria and now that we
have the right tools, it is no longer necessary to replace with original ‘as built’
scantlings. This will not only save weight and hence cost, but will avoid the harsh
transition of inserting ‘as new’ material in areas with general, but acceptable, wear
down, thus avoiding new areas of stress concentration or hard spots.

CROSSHEAD Conclusion

SafeShip is the visible face of a new way of doing things at ABS. Modern technology
and tools ensure good design is translated into a good product and is then monitored
in such a way that it retains the highest level of capability and safety. The diligent
application of these new tools will also enable operators to reduce both middle and
long-term costs of operation. What is not seen is the underlying use of database
technology and advanced communication techniques based on the STEP protocol and
the Ship Product Model that lie at the heart of the integrated system.

The SafeShip service has been introduced for SafeHull ships only, now that all of the
technology is in place to make such a service practical. Although it represents a
considerable financial commitment by ABS, it is helped by the ability to database
information on a piecemeal basis as it is collected. This is also the main reason why it
would be difficult, but not impossible, to apply the philosophy to existing non-
SafeHull vessels.

BOXED AT END OF ARTICLE:

David Robinson of ABS was recently transferred from his role as vice
president of technology and business development in London to be the
director of corporate technology in the ABS head office in Houston.
He was project manager for the development of SafeNet back in 1997
and has returned to Houston where he is now responsible for the
integration of rule and regulation information systems with
applications and the implementation of the 'SafeShip' programme
worldwide.




ABS SafeShip
ABS SafeShip

				
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