What Is the Standard Fender Size for an LNG Terminal?

The two most common fender sizes for LNG terminals are 3,300×6,500 mm and 4,500×9,000 mm pneumatic fenders, with 2,500×5,500 mm used at smaller berths handling feeder or mid-size LNG carriers.

“Standard” in this context means a size from the ISO 17357-1:2014 nominal series — not a regulatory minimum. The actual size for a given terminal is the output of the PIANC WG 211 berthing energy calculation. An engineer specifies the size that absorbs the calculated berthing energy at rated deflection without exceeding the vessel’s hull pressure limit.

The three LNG-relevant sizes from the ISO 17357-1:2014 series, at 50 kPa internal pressure and 60% deflection:

Performance tolerance ±10%. All figures per catalog, tested at 60% deflection / 50 kPa.

The 3,300×6,500 mm unit delivers approximately 146 kPa (kN/m²) hull pressure at guaranteed energy absorption — consistent with PIANC WG 211 §6.8.7, which notes that typical reaction pressures for foam and pneumatic fenders are in the order of 170 kN/m². The 4,500×9,000 mm unit covers the higher berthing energy range required for large displacement carriers such as Q-Max class.

Custom sizes outside the ISO 17357-1:2014 nominal series are available per Clause 6.3.3, but the standard series covers all common LNG vessel classes without customisation.

See the full ISO 17357-1:2014 standard size series and the pneumatic fender size chart for extended performance data.

LNG terminal fender size is determined by calculating the vessel’s effective berthing energy using the PIANC MarCom Report No. 211 (2024) method, then selecting from the ISO 17357-1:2014 standard size series a unit whose rated energy absorption at rated deflection exceeds that figure.

The core formula is:

E = ½ × M × V² × Ce × Cm × Cs

Where:
– M = vessel displacement (tonnes)
– V = approach velocity (m/s)
– Ce = eccentricity factor (hull geometry and contact point)
– Cm = virtual mass factor (added water mass effect)
– Cs = softness factor (fender system compliance)

The result, E, is the effective berthing energy in kilo-joules. The engineer selects the smallest fender from the ISO 17357-1:2014 series whose rated absorption at 60% deflection and design operating pressure exceeds E, with the required safety margin.

A secondary check compares the selected fender’s reaction force against the vessel’s allowable hull pressure. PIANC WG 211 §6.8.7 notes that typical reaction pressures for foam and pneumatic fenders are in the order of 170 kN/m², and §6.8.8 (Table 6-6) gives typical allowable hull-pressure capacities by vessel type; where vessel-specific limits are lower, a larger unit or wider contact panel is required.

Five inputs must be defined before the calculation can proceed:

1. Effective berthing energy (vessel displacement and approach velocity)
2. Allowable reaction force on the berthing structure
3. Maximum hull pressure the vessel can withstand
4. Fender position and contact area on the hull
5. Environmental conditions: wind, current, wave

Approach velocity is often the most variable input. PIANC WG 211 provides default values by vessel class and exposure category; a port’s operating procedures may specify tighter limits.

For a Q-Max carrier (266,000 m³ cargo capacity) at a normal berthing approach of 0.10–0.15 m/s, the calculation typically yields a berthing energy level requiring the 4,500×9,000 mm unit. A Q-Flex (~210,000 m³) under the same conditions typically calculates to the 3,300×6,500 mm unit.

See the LNG terminal fender system design guide for site-specific sizing support.

A Q-Max LNG carrier (approximately 266,000 m³ cargo capacity, ~345 m LOA) typically requires 4,500×9,000 mm pneumatic fenders based on its berthing energy calculated per PIANC MarCom Report No. 211 (2024); the final size must be confirmed by a site-specific calculation using actual vessel displacement and approach velocity.

A fully laden Q-Max has a displacement in the order of 165,000–175,000 tonnes (PIANC WG 211 gives LNG carrier displacement ≈ 1.33 × DWT + 1,400). At a normal berthing approach velocity of 0.10–0.15 m/s, the effective berthing energy using PIANC WG 211 inputs reaches the range the 4,500×9,000 mm unit (4,752 kJ / 5,747 kN at 50 kPa, 60% deflection) is designed to absorb.

The hull pressure check supports this choice. The 4,500×9,000 mm unit delivers hull pressures in the range PIANC WG 211 §6.8.7 describes as typical for foam and pneumatic fenders (in the order of 170 kN/m²); confirm against the specific vessel’s allowable hull-pressure limit for the project.

Treating this as a fixed rule is wrong. A lightly laden Q-Max at reduced approach velocity may calculate to a lower energy level. The 4,500×9,000 mm is the engineering default for full-load, standard-approach-velocity conditions at a berth designed for regular Q-Max operations — not a vessel-class assignment independent of the calculation.

Custom sizes outside the ISO 17357-1:2014 series are available per Clause 6.3.3, but the 4,500×9,000 mm standard unit covers Q-Max conditions without customisation.

The sizing basis differs between FSRU and fixed onshore LNG terminals, but both use the same PIANC WG 211 calculation method and ISO 17357-1:2014 product series — the deployment changes, not the engineering framework.

For an FSRU receiving an LNG carrier ship-to-ship, both hulls are floating. The berthing energy calculation accounts for the compliance of both vessels. Sizing follows PIANC WG 211 inputs alongside OCIMF Ship-to-Ship Transfer Guide guidance for STS operations. The result is often the same 3,300×6,500 mm or 4,500×9,000 mm unit used at fixed terminals.

For a fixed onshore terminal, the berth structure is rigid — concrete quay or pile-supported breasting dolphin. The allowable reaction force on the structure and the vessel’s berthing approach conditions may produce a different energy figure than the FSRU case, but the calculation method is identical.

See pneumatic fenders for FSRU and LNG terminals for FSRU-specific configuration details.

Typically 4–6 fenders are arranged along the berthing face of a fixed LNG terminal; FSRU ship-to-ship operations commonly use 2–4 fenders per side, depending on vessel parallel body length, dolphin spacing, and redundancy requirements.

Three variables determine the count:

1. Vessel parallel body length. For a Q-Max (~345 m LOA), the parallel body — the flat hull section available for fender contact — may span 150–200 m. Fenders must be distributed to cover this section without excessive point loading.

2. Dolphin or breasting structure spacing. LNG berths use discrete breasting dolphins rather than a continuous quay face. Fenders mount at each dolphin. A berth designed for Q-Max service typically has 4–6 breasting dolphins along the berthing face, so 4–6 fenders.

3. Redundancy requirements. Some terminal operators or project specifications require N+1 redundancy — a failed fender must not prevent safe berthing of the design vessel. This can push the count to 6–8.

Quantity and size interact. A berth using 4,500×9,000 mm fenders at 4 locations distributes the same total energy capacity differently from one using 3,300×6,500 mm fenders at 6 locations. The layout is a berth design output, not a rule derived from vessel class alone.

A JettyGuard sizing proposal includes a fender quantity recommendation alongside the size recommendation, based on the vessel’s parallel body and the berth structure drawing.

Yes — JettyGuard supplies the full standard range from 2,500×5,500 mm to 4,500×9,000 mm, all built to ISO 17357-1:2014, with per-unit test certificates and berthing energy calculation support included at the inquiry stage.

All three LNG-relevant sizes (2,500×5,500 / 3,300×6,500 / 4,500×9,000 mm) are standard catalog items. Each unit ships with reaction force and energy absorption test results at 60% deflection, pressure performance data, and full traceability to ISO 17357-1:2014.

JettyGuard’s manufacturing facility operates an ISO 9001:2015 quality management system, and fenders are supplied to ISO 17357-1:2014 with third-party inspection available (BV, DNV, or equivalent) — the documentation LNG terminal supply chain qualification requires.

For the full product range see pneumatic fenders. For system-level specification and supply, see the LNG terminal fender system page.