MOSS LNG Insulation
Repair & Upgrade Programs

Marine Gas Insulation AS has the only class approved refurbishment system for 0 - hour upgrade of SG (Spiral Generation) MOSS type LNG insulation

For an IMO type B Cargo tank in general, the main purpose of the insulation system is to:

  • Restrict heat ingress in order to minimize costs from lost cargo or expensive reliquefaction
  • Act as spray shield in case of tank leakage to protect the hull structure against critical temperatures
  • Allow for leak detection in case of tank failure
  • Allow for drainage and controlled evacuation of leaked cargo
  • Act as vapour barrier to minimize moisture ingress and accumulation

The original SG (spiral generation) insulation is prone to a variety of defects originating from the application process, material behaviour and operating conditions such as frequency of loading / de-loading – but generally all failure modes can be traced back to the design of the system itself. Defects will typically show after time and can be observed as extended de-lamination of vapour barrier and spray shielding, extensive and frequent surface cracking as well as complete through thickness cracking.

MOSS Insulation Upgrade Description

The MGI Thermo upgrade system is class approved and designed according to the IGC code specifically for the SG insulation system but can in principle be used for any MOSS type LNG tank insulation. The upgrade can briefly be described as follows: All through-going cracks will be repaired by injecting Polyurethane foam in order to seal damaged original insulation. The original combined vapour barrier and sprayshield is removed and replaced by a reinforced layer of polyurethane foam and a specially developed cryogenic polymeric coating. This method will minimize gas leakage through the insulation, hence reduce nitrogen consumption and improve vapour ingress protection. Additionally the thermal performance will be improved as the added Polyurethane has a very low conductivity, and increased tightness will minimize mass transport through the insulation

The upgrade system can be applied for repair of damaged insulation as well as for improved thermal performance of otherwise sound existing systems. The method can be used on complete tanks or only upper hemisphere according to the owners needs and requests.

MOSS Insulation Upgrade Advantages

An upgraded SG insulation system will be improved with respect to operational stability, environmental impact, safety and thermal performance:

  • Continuous application with full visual quality control
  • Conformance with Class rules
  • Eliminated need for frequent spot-repairs
  • Reduced Nitrogen consumption during operation
  • Reduced vapour ingress
  • Reduced heat ingress relative the original design:
    • A typical vessel guaranteed to 0.25%/24h BOR can be improved to reach 0.15-0.18 %/24h
    • A typical vessel guaranteed to 0.15%/24h BOR can be improved to reach 0.08-0.10 %/24h

Depending on the size of the vessel and the quality of the original insulation, this could potentially reduce the need for expensive reliquefaction with 30 – 60 tons of LNG pr. day

Insulation Repair Systems for
LPG, LEG, LNG - IMO type A, B & C

Ill conditioned insulation will result in increased heat ingress with corresponding loss of cargo as well as higher maintenance and operational costs. A well maintained insulation system saves money as well as the environment. MGI Thermo can offer insulation repair and upgrade solutions for most any kind of self supporting tanks for liquefied gas, independent of cargo temperature.

Typical Problems with Cold Insulation Systems

  • Panel insulation joint cracking does typically occur over time as glued joints become hard or the insulation bonding surfaces fails. Leads to increased heat ingress and potentially moisture ingress. For a panel system fixed with stud bolts or glue, moisture will condensate between tank and insulation leading to corrosion
  • Insulation de-lamination from the tank surface is a common problem for glued systems. It is often observed that large sections of insulation is completely disbonded and only held in place by the outer insulation cladding.
  • Support terminations are frequently observed having problems. Difference in thermo mechanical properties of insulation and support structure poses a great challenge for proper design and application. The result is ice build-up on the supports where the heat ingress is too large. Ice formation typically induces ice wedging causing the insulation to disbond, leading to further deterioration and moisture ingress.

Tank Insulation Repair Solutions

MGI Thermo can offer tailor made insulation solutions for any kind of self supported tanks. When possible, our principle is to rectify damaged areas with polyurethane spray foam, ensuring best possible bonding to the cargo tank as well as to adjoining original insulation. For IMO type B tanks or A and C where the original insulation is not bonded to the tank surface it will be a case by case consideration if the repair insulation will be new panel inserts, spray foam or a combination of both. No repair job is the same so detail knowledge of each different system as well as practical experience is important for a satisfactory result.

  • Insulation inspection and status reports for repair and maintenance of vessels in operation, including repair procedures and cost estimates
  • Supply of engineering, supervision, materials and installation for insulation repairs during docking or voyages
  • Repair or upgrade of LPG, LEG and LNG cargo tank insulation with polyurethane spray foam or tailored solutions
  • Partial or full replacement of existing insulation on-board during docking. All insulation materials and systems are approved by class society
  • Full insulation replacement will give same properties as for a new-building, and can meet the latest BOR requirements
  • Renewal of insulation can be planned area by area to fit the vessels' operation program
  • Training and instruction of ships' crew for insulation maintenance and small repair

Pipe Insulation Repair

MGI Thermo offer various solutions for pipe insulation repair in cooperation with our partners:

  • Conventional pipe insulation with one or two layers of pre-fabricated pipe sections with GRP or glass cloth and mastik
  • Pre insulated pipe system in cooperation with LR Marine
  • World wide material deliveries, installation and supervision