IMO IGF / IGC CODE • 9% NICKEL STEEL • DUAL-FILE SPMT SUPERLOAD

800-Ton Cryogenic IMO Type-C LNG Fuel Tank Transport Manual

Authoritative heavy transport engineering standard for maritime dual-fuel bi-lobe and cylindrical Type-C pressure vessels: saddle cold breaks, positive nitrogen blanket retention, and shipyard roll-on/roll-off (RoRo) load-outs.

Payload Envelope
350T – 850T
Bi-lobe & cylindrical geometry up to 55m length and 9.5m OD.
Metallurgy & Design Temp
-163°C (110 K)
ASTM A553 9% Ni steel inner shell with austenitic outer jacket.
Insulation & Vacuum
< 1×10-3 mbar
Multi-layer vacuum insulation (MLI) or expanded perlite matrix.
SPMT Configuration
2 × 24 Axle Lines
Dual-file synchronized platform with 3-point hydraulic leveling.
01

Saddle Structural Shoring & Thermal Cold-Break Blocks

IMO Type-C cryogenic tanks feature fixed and sliding support saddles designed to accommodate significant thermal contraction during liquid nitrogen pre-cooling and LNG bunkering. During highway and shipyard modular transport, the following structural load-bearing parameters must be maintained:

Densified Laminated Wood (Permali) Interfaces

Tank-to-saddle contacts utilize resin-impregnated densified beech laminate (Permali / Dehonit) with compressive strength ≥ 120 MPa. Under road transport dynamic loading (±0.5g lateral, ±0.3g longitudinal), no metal-to-metal contact is permitted between outer saddle steel and the vacuum containment jacket.

Sliding Saddle Locking Keys

While in marine service one saddle expands and contracts freely along low-friction PTFE/stainless slide plates, during heavy haul transport temporary high-shear transit locking pins must be inserted to prevent unconstrained longitudinal sliding during braking or incline ascents.

02

Inert Nitrogen Blanket & Annular Vacuum Telemetry

Unfilled Type-C tanks dispatched from manufacturing plants to shipyards travel under positive nitrogen blanket to prevent internal atmospheric moisture ingress, which causes ice crystallization and valve seat scoring during initial cryogenic cool-down:

Internal N2 Blanket
0.3 – 0.5 bar(g)
Grade 5.0 dry nitrogen (dew point < -60°C)
Annular Vacuum Watch
< 0.05 mbar
Continuous Pirani gauge digital readout
PRV Setpoint Setting
4.5 bar(g)
Dual redundant ASME VIII / IMO pilot valves
03

Multi-File SPMT Kinematics & 3-Point Hydraulic Suspension

Due to the extreme center of gravity (CoG) height of 800-ton bi-lobe fuel tanks (typically 4.8m to 6.2m above ground), transport configurations require wide-track multi-file SPMTs:

  • • 3-Point Hydraulic Support Grouping: SPMT hydraulic cylinders are grouped into three independent hydraulic circuits (one virtual apex at the front, two lateral circuits at the rear) to ensure determinate load distribution over roadway cambers without torsional chassis twisting.
  • • Tipping Angle Security Margin: The static stability angle must exceed 8.0° across all transverse slopes, with maximum allowable crossfall during transport restricted to 2.5% (≤ 1.4°).
  • • Ground Bearing Pressure (GBP): Steel load distribution grillage beams over the SPMT platforms distribute maximum wheel line axle loads ≤ 16.5 metric tonnes, keeping quayside quay wall bearing pressure ≤ 18.0 t/m².
CRYOGENIC SUPERLOAD LOGISTICS SPECIFICATION

Consult an Exspeedite Cryogenic Transport Architect

Request route surveys, SPMT axle load simulations, and IMO IGF saddle shoring reviews for marine fuel tanks.