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OFFSHORE E-NEWS
May 2000
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JUST-RELEASED: UPDATED ABS
GUIDES
For Floating Production Installations;
Production Facilities;
and Pipelines and Risers
Incorporating
the latest engineering developments and, also, ABS’ broad-base
experience with offshore clients ranging from oil companies, independent
owners/operators, designers and fabrication facilities, the updated
ABS Guides provide ABS class requirements for the following:
Floating
Production Installations
The new Guide
for Building and Classing Floating Production Installations
is an update of the 1996 ABS FPSO Guide with the focus of
the improvements on requirements for ship-shaped FPSOs. This new
criteria is appropriate for newbuilds and major conversions, and
allows owners and operators of FPSOs to tailor the hull structure
of an FPSO to the expected conditions of its installation site.
This is especially relevant since FPSOs have typically been subject
to "unrestricted service" requirements of tankers, even
when the FPSO is located in an area where the environmentally-induced
loads are far below those typically faced by a tanker.
To allow for
this level of customization, the Guide uses ABS
SafeHull technology to separate and analyze static and dynamic
load effects.
"In the
case of an FPSO located in a relatively benign environment, ABS-required
hull scantlings for a newbuilding would likely be rationally reduced
below those required in unrestricted service for a tanker,"
says Todd Grove, Manager, ABS Offshore Engineering. "For a
conversion, it would likely reduce the amount of potential steel
renewal. In the case where the environmentally-induced loads are
more severe than those for unrestricted tanker service, the Guide
will assist the designer in determining how much the strength of
the hull needs to be increased, or in otherwise providing information
to assist in mitigating the loads it needs to resist."
Because environmental
severity evaluation relies upon highly specific data, a Site-specific
Environmental Analysis System (SEAS) was employed to find environmental
severity factors contributing to determination of the loads and
expected fatigue-induced damage. Characteristics like wind, wave,
current and other data are factored into analysis models.
The new Guide
criteria allows owners and operators to better design FPSOs, making
them more appropriate for their intended service in offshore production
areas worldwide.
Production
Facilities
The updated
ABS Guide for Building and Classing Facilities for Offshore Installations
incorporates the latest technological developments for production
facilities on fixed and floating structures, and addresses the stresses
induced by acceleration forces of floating installations.
"What often
happens is that an oil company will contract a manufacturer to construct
the process equipment skids, but the manufacturer will not know
whether the skids are to be installed on an FPSO, with vertical,
horizontal, heave and pitch motions, or on a TLP, which moves much
less," said Malcolm Sharples, Vice President, ABS Offshore
Technology and Business Development. "The motions of these
platforms are very different, and they may have unique effects on
equipment. In fact, equipment not designed for a particular environment
may not work at its best efficiency."
The Facilities
Guide also incorporates criteria for alternative use of a risk
methodology derived from OSHA’s Process Safety Management and
US EPA’s Risk Management Program regulations, opening the door
to risk-based design. This means that the risk analysis is tailored
to the risks associated with a particular equipment design, and
addresses areas of concern on an item-by-item basis.
Pipelines
and Risers
The updated
ABS Guide for Building and Classing Undersea Pipeline Systems
and Risers has gained in importance as offshore installations
venture to deeper waters and risers, in particular, become critical
to the safety of the rig, the reliability of production / transportation
and the protection of the environment.
"The update
of the pipelines and risers guide reflects research and technical
developments that have occurred around the world in the offshore
industry," said Dr. Yong Bai, ABS Staff Consultant, Offshore
Technology Department.
The guide also
incorporates recent award-winning research by Bai and ABS colleague
Søren Hauch on the bending moment capacity of pipes. In this
study, which won the "Best Paper Award" from ASME’s
Ocean and Offshore Arctic Engineering Division, a set of equations
were developed that can more effectively predict the ultimate load
carrying capacity of pipes when subjected to combinations of pressures,
axial force and bending.
"The purpose
of our research on the bending moment capacity of metallic pipes
is to develop design criteria that can help optimize the cost effectiveness
of the seabed intervention design without compromising the safety
of the pipe," explained Bai.
The updated
Guide consists of four parts:
- Classification,
testing and survey
- Materials
and welding
- Design
- Inspection
and maintenance.
In addition,
the Guide contains four appendices for information
- Limit state
design criteria
- Structural
reliability analysis
- Risk management
- Assessment
of dent and corrosion defects.
A copy of the
paper, "The Bending Moment Capacity of Pipes," can be
downloaded from the ABS web site, at www.eagle.org
or contact Jo Feuerbacher at 1-281-877-6516 or email jfeuerbacher@eagle.org.
To order any
of these or other ABS Guides, click
here .
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