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“Natural gas has become much more than a secondary oil by-product
that must be moved, processed, reinjected or flared. We have new options.
As worldwide demand for natural gas increases, ABS can assist the
industry with a single-source set of guidelines for safe alternative
means of transporting, and therefore of marketing, this cleaner-burning
energy source,” said Sember.
Sember advises that the new ABS guide will facilitate CNG industry
development, providing a comprehensive framework of reference material
while identifying acceptable methodologies for achieving class society
approval of new CNG technology.
“We are responding to our energy clients with the necessary
technical standards and guidance for transporting, storing, offloading
and containing gas,” said Sember.
CNG Market Niche
Relatively long distances between the gas
sources and markets or difficulties associated with accessing remote,
deepwater offshore fields may make pipelines prohibitively expensive
for otherwise promising gas projects.
Because many worldwide gas-producing fields lack suitable infrastructure
for liquefying natural gas, and because terminal re-gasification
facilities may be similarly limited, transportation of this “stranded”
gas in compressed rather than liquid form offers cost and operational
benefits.
For example, gas can be loaded directly onto newly designed gas
carriers from offshore production facilities, increasing safety
and decreasing security concerns. The gas can be compressed and
contained onboard, eliminating the need for costly liquefaction
and re-gasification processing.
In some designs, CNG carriers also can discharge gas directly into
terminal facilities located offshore, further minimizing potential
impact to population centers and areas of high environmental sensitivity.
These operational benefits are indicative of the potential for
CNG market growth as new technological milestones are reached, says
Philip Rynn, ABS senior engineering staff consultant.
“ABS is helping industry stay ahead of the curve, defining
criteria for the technology validation process,” said Rynn.
The ABS CNG
Guide and the International Gas Code
The CNG guide builds upon the International
Gas Code (IGC) of the International Maritime Organization (IMO)
as a platform of regulatory standards accepted by the international
marine community. However, progressive and novel concepts in CNG
may require new directives, says Sember.
“Operators and developers are calling upon us to provide
more risk-based classification guidance than ever before. CNG technical
advancements call for more application of risk-based assessment
because the traditional codes and inspection rules don’t apply,”
he said.
Approval
in Principle
The guide addresses the development of novel
ship and containment designs with the goal of achieving ABS approval
in principle (AIP), a fast-track alternative to prescriptive classification
rules and the first step in the regulatory and vessel certification
process.
First applied to short hauls of small gas volumes, these developing
concepts now promise a new generation of CNG solutions. Recent examples
include:
- The TransCanada proposal for a gas transport module (GTM),
based upon the company’s composite reinforced pipeline (CPLP);
- The Coselle vessel design with a containment system that uses
small diameter pipe in coiled cylinders for longer periods of
sea transport;
- The Trans Ocean Gas proposal utilizing composite pressure vessels
in the hold of a ship; and
- The VOTRANS (Volume Optimized Transport Storage) concept of
EnerSea Transport LLC, Hyundai Heavy Industries Co., Ltd. and
Kawasaki Kisen Kiasha, Ltd., which employs 2,400 modular bottles,
racked vertically and about six inches apart.
ABS Requirements
Underlying the approval and classification
process, ABS risk studies identify the hazards posed by CNG loading
procedures and other ship operation parameters. In assessing these
procedures and parameters, the guide conforms to the American Petroleum
Institute (API) codes for system safeguards.
Before previously stranded gas can be transported, however, flag
states signatory to IGC require provision for regulatory equivalents.
Coastal states and local authorities at load and discharge must
approve safety factors.
Sember advises that communication among all involved parties, including
concept developers, system designers, materials manufacturers, shipyards,
operators, regulatory bodies, export and import states, can be coordinated
by ABS.
“Historically, regulation generally follows after innovation.
We are pleased to say that in this instance, development of rules
and standards are taking place in partnership with a class society,
allowing for innovation and the incorporation of new risk methodologies.
“The new ABS guide assists with a probabilistic approach
to identifying hazards, determining departures from existing codes,
providing equivalents and evaluating safeguards. This is the role
classification plays in helping industry and operators face their
development challenges,” he said.
The new ABS Guidance Notes for Building and Classing Ships
Carrying Compressed Natural Gas will be available soon for
free download on the ABS web site, Rules and Guides section.
Read details and view graphics of
existing and proposed CNG technology discussed at OTC.
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