Lloyd’s Register issues approval in principle to GTT for updated NO96 LNG carrier hull elongation criteria

Lloyd’s Register has issued an approval in principle to GTT covering revised hull elongation criteria for LNG carriers equipped with the NO96 cargo containment system. The AiP confirms that GTT’s updated criteria—governing allowable hull deformation beneath the NO96 membrane and insulation system—meet Lloyd’s Register’s classification requirements and applicable international regulations.

The assessment examined operational, thermal, and hull-induced loads across a representative LNG carrier design, including compatibility with NO96 variants and relevant hull geometries.

Lloyd’s Register approves GTT’s revised NO96 elongation criteria

This AIP is a formal endorsement from one of the world’s leading classification societies. Lloyd’s Register confirmed that GTT’s revised criteria—which govern how much a ship’s hull can deform beneath the NO96 membrane and insulation layers—stay within established safety margins. That’s a meaningful benchmark. Hull elongation affects the mechanical behavior of the entire containment system, so any revision to those thresholds needs rigorous independent verification before it can be applied in practice.

The system also appears in complex, high-specification gas carriers and other marine vessel designs where structural assurance is a non-negotiable requirement.

This wasn’t a simple desk review. LR’s technical team examined operational loads, thermal conditions, and hull-induced stresses across a representative LNG carrier design—the goal being to confirm the updated criteria hold up under real-world conditions, not just on paper. That kind of multi-load assessment is standard for containment system approvals, but the scope here reflects how seriously both parties treat changes to foundational design parameters.

Why GTT developed the updated criteria

GTT developed the revised elongation criteria as part of its ongoing innovation program—a broader effort to keep the NO96 system competitive as vessel designs grow more complex. The specific driver was flexibility. Hull structural design involves a web of competing constraints, and more refined elongation criteria can open up design space that wasn’t previously available to naval architects.

The updated criteria don’t relax safety standards. GTT maintained established stress limits, fatigue margins, and membrane performance requirements throughout development. The idea is to give designers more room to work within those limits — not to move the limits themselves.

LR’s review reinforced that distinction. The classification society ran detailed structural and hydrodynamic analysis based on a representative LNG carrier design, checking compatibility across NO96 variants and verifying alignment with applicable load cases and hull geometries. That level of scrutiny is exactly what an AiP is designed to provide: independent confirmation that a new technical approach is sound before it gets built into an actual vessel.

Implications for LNG vessel design and construction

The practical upshot for designers and shipbuilders is real. Updated elongation criteria that have already cleared LR’s review can be applied earlier in the design process, cutting uncertainty during a phase when changes are still relatively easy to make. Early-stage confidence matters — it can shorten design cycles and reduce the risk of costly revisions down the line.

A structural benefit also emerges. The updated criteria enable more efficient optimization of NO96-equipped hulls, with possible reductions in lightship weight—the vessel’s mass without cargo, fuel, or crew—which is a key factor in overall efficiency and commercial performance. Even modest reductions can have meaningful effects across a vessel’s operating life, compounding over thousands of voyages.

Compatibility was confirmed across NO96 variants, applicable load cases, and relevant hull geometries. That breadth matters because LNG carriers aren’t a single uniform design. Vessel specs vary by owner, route, and cargo requirements, so criteria that only work for a narrow subset of hulls would have limited practical value.

Context: NO96’s role in the global LNG fleet

NO96 is one of the most widely deployed cargo containment systems in the global LNG fleet. Its prevalence means that technical updates — even incremental ones — can ripple broadly across shipyards, owners, and operators. The system also appears in complex, high-specification gas carriers and other marine vessel designs where structural assurance is a non-negotiable requirement.

As vessel designs become more structurally optimized and technically demanding, early-stage technical validation has grown in importance. Classification societies like LR are increasingly involved at the concept and preliminary design stages rather than just during construction. AiPs are one of the primary tools for that kind of upstream engagement.

Both companies highlighted that dimension in their responses to the approval. Constantinos Chaelis, Global Gas Segment Director at Lloyd’s Register, said: “This approval is about giving confidence at an early stage. Our review confirmed that GTT’s updated NO96 elongation criteria remain within established safety margins while allowing designers greater flexibility. This kind of technical validation is essential as vessel designs become more optimized and structurally demanding.”

François Michel, CEO of GTT, echoed that framing: “Lloyd’s Register’s AiP confirms the technical robustness of the latest NO96 developments. These enhanced design criteria provide greater flexibility for ship designers while preserving the highest standards of safety and membrane integrity.”

The key takeaways are straightforward. Lloyd’s Register has formally confirmed that GTT’s revised NO96 hull elongation criteria meet classification and regulatory requirements—criteria that give designers more flexibility without compromising established safety or performance standards. The approval covers a representative LNG carrier design and applies across NO96 variants and relevant hull geometries, positioning both GTT and shipbuilders using the NO96 system to pursue more structurally efficient vessel designs with a credible technical foundation already in place.

Kelly Lippke

Kelly is an experienced writer with 15 years of experience exploring the big stories that shape our world, from tech breakthroughs and space exploration to climate, energy, and the fascinating quirks of science. She has a talent for turning complex ideas into sharp, memorable insights that stay with readers long after they’ve finished reading.