Bulk Storage Facilities
Bulk Storage Facilities
At Fleury Engineering, we offer a complete service for your bulk storage facilities to ensure product quality and environmental compliance.

+ Project Management
+ Risk Assessment
+ Design
+ Installation
+ Health and Safety Compliance
+ Waste Minimisation
+ Decommissioning and Demolition
+ Decontamination
+ Inspection and Testing
+ Auditing

The Problem of Fuel Contamination

Once diesel leaves the refinery, it is subject to contamination at every point along the supply chain. Water/condensation, corrosion deposits, microbial growth and even the diesel itself can present problems over time.

Diesel Bug

Almost all diesel contains some microbes, which can enter storage tanks via filling inlets and vents, as they are present in the air. At low levels, these do not pose a problem but if a microbial population takes a hold, it can cause serious problems for fuel quality. The growth of bacteria, yeasts and fungi in stored fuel is often termed “diesel bug”.

The main things these microbes require are food, water, oxygen or sulphur and some trace minerals. They reside at the fuel/water interface, consuming the hydrocarbons in the diesel and living in the water. If they are aerobic, they consume oxygen dissolved in the water and if they are anaerobic, they consume sulphur and produce corrosive compounds as a result.

The visible symptoms of diesel bug include:

  • Slime. This can look like treacle, mouse or candy-floss

  • Thick slimy mats at the oil/water interface

  • Black deposits in diesel like coffee grounds

  • Murky diesel

  • Under suitable conditions (especially where water is present in tanks), these microbes can multiply from a single spore to several kilograms of slimy mass overnight. Often the growth is less dramatic but it can still pose major problems for fuel stored for a long time, such as over 6 months. As well as having a significant impact on fuel quality, these micro-organisms can consume rubber gaskets, O-rings, hoses, tank linings and coatings in an effort to obtain their mineral content.

    Consequences of Diesel Bug

    The presence of microbial growth in fuel storage tanks can cause major problems:

  • Reduced start-up reliability

  • Reduced engine life

  • Reduced efficiency

  • Higher emissions

  • Diesel bug can 'spoil' the fuel and the sludge can be drawn into the engine, quickly clogging filters, causing loss of power, narrowing fuel lines and eventually leading to engine breakdown. If anaerobic microbes take a hold – often adhering to the tank walls and fuel lines - corrosive hydrogen sulfide can be produced. This causes corrosion and pitting of the injectors and other components.

    Fuel deterioration

    Even if diesel bug is avoided, the diesel itself will cause sludge deposition over the long term. This is because “middle distillate” fuels are inherently unstable and will deteriorate over a period of months. Most fuel suppliers will not guarantee fuel in bulk storage beyond a few months to a year.

    Emergency Generators

    While fuel contamination is a major issue for vehicle fuel, for emergency generators, the results of a “no-start” can be catastrophic. If you rely on a back-up generator, then you need to be sure that it always has a clean fuel supply.

    Prevention and Treatment of Water Ingress, Microbial Growth and Sludge Build-up

    Ensuring that fuel is free from water is the main preventative action required for Diesel Bug. Periodic sampling and inspection is required to test fuel quality and tank integrity. If water and/or sludge are present then they must be removed and the opportunities for re-occurrence minimised. Fleury Engineering can provide a complete service to ensure that you maintain the quality of your stored fuel.

    Tank Cleaning

    We have cleaned fuel and chemical tanks from 150 litres to 10,000 tonnes. Using advanced equipment and highly experienced personnel, the result is a tank safely cleaned with the minimum of disruption to the owner. Where possible, we clean tanks using non-entry techniques (See Fuel Cleaning). If entry is required, all our personnel are trained and experienced in confined space entry and the use of breathing apparatus.

    Tank Inspection

    A range of inspections from routine external to detailed structural surveys are provided.
    Corrosion is the biggest enemy of storage tanks. This can be internal or external. With Fleury Engineering, you can get your tanks inspected to API 653 standard.

  • Ultrasonic testing

  • Underfloor corrosion

  • Magnetic Flux testing

  • Pipelines

    Over-ground or underground pipelines are always at risk from corrosion and collision. Fleury Engineering can inspect your system using non-destructive techniques to ensure that you are safe from causing environmental pollution or losing product from pipelines.

    Diesel Bug Biocides
    We can engineer systems to minimise water ingress and to actively remove water and other contaminants. However, growth of diesel bug can be further prevented by dosing the fuel storage system with biocide. See Products.

    Fuel Dispensing

    Fuel is a major cost to fleet owners. Proper management of supply, storage, dispensing and consumption is crucial to minimise fuel, vehicle servicing and environmental costs. It also minimises opportunities for operator error and theft. Fleury Engineering can provide a customised solution to meet your fuel dispensing system needs.


  • Marine vessels

  • Rail

  • Haulage contractors

  • Plant and machinery

  • Service vehicles

  • We can provide complete management systems incorporating:

  • Dry-break couplings – no more spills

  • Automatically recorded metering

  • Automatic usage tracking via tagged nozzles and inlets

  • Automatic Inventory recording

  • We can provide a highly automated system which tracks how much fuel is dispensed from which tank, by which operator, to which vehicle and at what time and date.


  • Fuel savings

  • Faster refuelling times

  • Reduced environmental damage

  • Reduced inventory management time

  • News
    12 February 2014
    Fleury Engineering has recently completed several large fuel recovery projects for industrial users and oil distributors in Ireland and the UK. Oil...
    31 May 2012
    Fleury Engineering is proud to have been awarded with ISO Certification in Quality (ISO 9001:2008) and Environmental
    (ISO 14001:2004) Management...
    Marine Fuelling Systems
    We build complete marine fuel storage and dispensing systems. Our systems are designed specifically for the marine environment....
    Data Centre Standby Generator Fuel Cleaning
    Avoid generator failure by keeping the fuel in the tank at its best. Over time diesel will break down due to exposure to heat, oxygen and moisture.