Internal Floating Roofs IFR’s- Pontoon and Full Contact Types

..... In a nutshell


An internal floating roof, or IFR, comprises a steel or aluminium deck, which floats on, or just above the surface of the product within a vertical cylindrical storage tank. This deck has a seal around the outer edge which is tight enough to form a barrier but flexible enough to allow the deck to rise and fall with product level within the tank.



Because a correctly functioning IFR will prevent vapours from leaving the surface of the product and occupying the vapour space with a storage vessel – with adequate sealing, these vapours will remain below the deck which has a number of key benefits. Firstly, you protect the product from contamination with air and the moisture it contains – this is important with aviation fuels and in marine environments where ingress of air could also mean ingress of salt and moisture. Secondly, when the vapour space is occupied by air rather than a volatile vapour, it makes for a safer installation. Lastly, when a tank fitted with an IFR breathes or fills/empties, it will vent air rather than the valuable/dangerous/odorous/volatile/noxious vapour (product) which sits below the IFR.

In smaller tanks, a nitrogen blanket is often used as an alternative to an IFR. As the tank size increases, blanketing can become expensive unless nitrogen is freely available, making an IFR a cost effective long term solution.



Usually on large tanks (upwards of 15m diameter), IFRs are used by Fuel Terminals, Airports, Refineries, Fine Chemical Manufacturers, Sewage Works and anywhere where valuable, volatile, safety critical or finely refined product is stored.

IFR technology dates back to the 1950s and has evolved in line with the demands of customers and to keep abreast of legislation. Tank inspections are now routinely performed in 10 – 20 years intervals. Therefore, it is important that the IFR performs effectively throughout this period, without the need for intervention and maintenance. Pressure on profit margins can drive cost-cutting on capital equipment purchases and concurrent pressure to prevent production outages, so inspection schedules are likely to be pushed out even further. It is, therefore, important that any IFR technology meets those demands and performs robustly at optimum level for longer periods of time than ever before.

Assentech has an enviable reputation for delivering quality at a competitive price. We have now completed many projects on time and on budget with commendations and testimonials from major UK infrastructure companies. Every IFR or Geodesic dome we fit has been engineered to suit the specific tank application. Drawings will be produced with specific details of the deck or dome complete with customer details, tank layout including location of key items such as manways, dip funnels etc. Our customers can’t afford to take risks with this kind of equipment. A failed IFR or collapsed dome is unthinkable so we rightfully question why some customers buy cheap decks and domes that are proposed without any apparent up front engineering or documentation.

IFR’s are fitted for one reason, to stop vapours leaking to the atmosphere. Tank inspection periods run from between 10 years and up to 20 years in some industries so why do customers buy cheap wiper seals that last only 3-5 years. Our stainless steel shoe seals last for at least 25 years. We feel that our fitted IFR’s give the best life cycle cost through sound engineering solutions.

The IFR’s we work with are designed and manufactured by Matrix Applied Technologies. Matrix Applied Technologies have long been the global leader in the design and manufacture of IFR’s, with 25 years practical tank experience and installations in over 80 countries Worldwide.

We primarily offer two types of IFR from Matrix Applied Technologies, their Heavy Duty Aluminium Pontoon Type IFR and the Matrix Applied Technologies Full Contact Aluminium Honeycomb Panel IFR. Each has been designed to overcome the many design problems that exist in other well-known brand IFR’s – offering value for money through low cost of ownership and long term durability.

Heavy Duty Aluminium Skin and Pontoon Internal Floating Roof

63The Matrix Applied Technologies heavy duty IFR comprises 5 core elements, a central frame, a deck, pontoons, landing legs and rim seal. The deck sits on top of the pontoons which allow it to float clear of the product surface. When the tank is emptied, the IFR lowers onto legs which prevent it from fouling on the tank floor or in tank equipment such as inlets and stirrers.

Structural integrity is at the core of the design and the result is an IFR which is not only suitable for tanks which are subject to high sloshing and/or turbulence but has also been approved for installation in areas prone to earthquakes.

When investing in an IFR, there is never 100% certainty of what the future holds for the tank. It may in the future be subject to a change of duty, be modified or require additional gauge poles and these factors need to be considered on purchase. Many of the IFR’s offered by our competitors have structural integrity which relies upon the collective strength of the integral components. This is not a long term solution as it makes future repairs or modifications impossible – after all, you should be able to change your windows at home without the house falling down.

The Matrix Applied Technologies Heavy Duty pontoon type IFR is different – the strength core is provided by a rigid central frame, to which the pontoons, landing legs, rim seal and deck are fastened. This means that in years to come, repairs or modifications can be made to the deck, pontoons or seal without requiring total replacement of the IFR.

This is not the only part of the design where Matrix Applied Technologies think diffe

Tank Internal Floating Roof-Pontoon Type

rently – for instance – Matrix Applied Technologies floatation pontoons are hung below the deck on custom designed straps which spread stress evenly over the pontoon, making it independent of the structure. Many competitor designs incorporate the pontoon within the structure – this is a shortcut because although it means less metal and less cost up front, pontoons are not a structurally able to cope with cycling stresses and almost always result in cracking of the ends. This leads to leaking pontoons, a sinking deck and problems with de-gassing.

These are just two design choices which set Matrix Applied Technologies apart. There are many other which we would happy to discuss including;

  • Heavy duty as standard – sturdier construction than most other types
  • Landing Legs are not connected to the pontoons
  • Easy assembly – quicker and cheaper installation
  • Extruded rim allows fitting a shoe seal without rim reinforcement
  • Coil type anti-static/earth connection eliminates fouling problems
  • Heavy duty Shoe seal offered as standard (other seal types available on request)
  • Deck sheeting is fastened from the top making it accessible and easy to modify in the future
  • 0.6mm (0.024”) thick main deck sheeting as standard – it will not puncture or tear easily
  • All fasteners are stainless steel
  • 1000lb/ft² load capability – the majority of decks will just about cope with the API standard of 500lb/ft2
  • We can coat and anodise our IFRs to suit your particular requirement

Heavy Duty Full Contact Internal Floating Roof-Aluminium Honeycomb Panel IFR

64The Matrix Applied Technologies Full Contact Honeycomb Panel IFR consists of a deck which floats with its bottom surface in full contact with the stored liquid. Unlike a pontoon type IFRs, there is no vapour space beneath the deck panels of a full contact IFR.

The Matrix Applied Technologies Full Contact Roof uses a unique (Patent Pending) & simple panel to panel bolted connection system with continuous sealing between the panels – ensuring leak free seams. Each panel is pressure tested to ensure it meets Matrix Applied Technologies’s stringent quality standards.

Tank Internal Floating Roof-Full Contact Type

Many full contact IFRs are made from standard panels which are modified on site and have the landing legs fitted in a pattern which is vaguely symmetrical and relies on fittings piercing the panels. This not only results in uneven loading but every time a panel is pierced you risk loss of containment and structural integrity. The Matrix Applied Technologies deck is custom built and designed down to the last fastening. Every landing leg is situated in a designated sleeve which sits outside of the panels and is structurally reinforced.

These are just two design choices which set Matrix Applied Technologies apart. There are many other which we would happy to discuss including;

  • Heavy duty as standard – sturdier construction than most other types
  • Landing are considered in the design and located in strengthened sleeves, not bolted through the middle of panels
  • Easy assembly – quicker and cheaper installation
  • Additional rim buoyancy to prevent the rim seal from causing outer panels to sag
  • Extruded rim allows fitting a seal without rim the need for additional reinforcement
  • Coil type anti-static/earth connection eliminates fouling problems
  • Heavy duty Shoe seal offered as standard (other seal types available on request)
  • All fasteners are stainless steel
  • 500lb/ft² load capability
  • We can coat and anodise our IFRs to suit your particular requirement

Internal Floating Roof Installation

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At Assentech, we offer a complete installation service provided by our team of Matrix Applied Technologies trained confined space installation engineers. If you would prefer to use local staff for your installation, we will consider providing a project manager and site supervisor to oversee the team of your choice as long as they are suitably skilled and qualified.


All of our engineers are fully insured to work on COMAH sites and we provide Risk Assessments and Method Statements in advance of all work as standard.


A common criticism of our competitors is that they apply hidden costs during or after installation. At Assentech, we pride ourselves in working to a fixed price which includes everything you require, from an inlet diffuser to roof vents, floor plates and site welfare – because we would rather you know the costs and remove the options you don’t require than get any nasty surprises.

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