TANK LINING

When we receive your tank lining enquiry it is important to understand the clients requirements to solve the tank lining problem. There is no one size fits all tank lining solution, despite what other tank lining contractors may promote. Important considerations when considering undertaking a tank lining or tank relining are as follows;

• Type of Substrate – steel, concrete and GRP are some of the common tanks that we apply linings to. Each of these different substrates have intricacies that mean that not one type of tank lining is suitable for all.
• Substrate Condition – new tanks often require a different preparation approach compared to old tanks with existing tank linings.
• Access – Tanks by their nature are nearly always a confined space. Safety is our number one priority when undertaking tank relining projects and an essential consideration is how to access the tank safety. The very largest tanks we have relined have been large enough to drive scissor lifts inside, the smallest to small to stand in. This is an important consideration as the tank lining material used can introduce a new hazard into the confined space and this risk needs to be managed when undertaking the tank lining works.
• Regulatory requirements – many tank linings may require an approved tank lining system. Examples are when undertaking water tank linings used in the public supply (DWI regulation 31) or approved tank linings for use in diesel and fuel tank linings.
• Operating temperature – the temperature at which a tank lining needs to operate can drastically change the tank lining solution required. Elevated temperatures increases the aggressiveness of any chemicals contained within the tank. A tank lining which is suitable for ambient conditions might not be suitable for elevated temperatures. Tanks which operate at elevated temperatures may also require higher standards of preparation to ensure compliance with the manufacturers recommendations and the performance of the new tank lining.
• Chemicals – many of the tanks we reline contain aggressive chemicals such as acids, alkalis, hydrocarbons or combinations of different chemicals. When undertaking chemical tank linings it is essential that all information relating to the chemical stored and any parameters in the production or storage of that material are properly understood and passed on to the tank lining manufacturer.
• Local Environment –  tank lining works can involve noise and dust producing operations such as grit blasting and ultra high pressure water jetting. Solvent containing tank lining materials that fulfil other requirements might not be suitable due to the type of tank or the tanks location. All of these factors need to be considered and communicated to the tank lining material supplier and if hazards such as noise, if dust and fumes cannot be designed out control measures need to be put in place to mitigate these hazards. The local environment can also mean that heating or dehumidification is required to ensure the correct conditions for applying the tank lining to ensure compliance with the tank lining manufacturers recommendations.
• Timescale – many of the tank linings we apply take place in planned production outages or shutdowns. This can often mean a restricted time scale for the tank relining process for the works to be undertaken within. This can affect the tank lining material used or how the tank relining is undertaken. An example of this is the curing period required following the application of the tank lining. Typically for epoxy tank linings this is seven days, however very fast curing tank linings are available which can be returned to service in less than 12 hours.

Unlike some tank lining contractors we deal with many different supply partners. This offers us a broad selection of tank lining material options, which given all of the considerations mentioned previously is essential given the huge variety of tank linings we undertake.

We can provide a choice of tank lining systems with differing life expectancies, warranty periods or timescales to fit around our clients budgets and project requirements.

The majority of our supply chain partners are companies that we have worked with for extended periods, giving us confidence in the materials that we used and the integrity of the manufacturer. An intimate knowledge of the tank linings systems available allows the best fit for the clients need to be selected.

Good communication with the tank lining manufacturer is critical to them understanding the specific requirements of a project and allows the identification of the correct application of their proposed tank lining.

Innovation is a key part of how we approach tank linings and if there is a new material that aligns with our objectives of improving the life expectancy or reducing the environmental impact of our operations.

Once suitable tank lining materials have been identified a proposal is developed identifying how the works will be undertaken and the provisions required to facilitate a successful tank lining installation. A key part of this process is identifying the quality assurance checks and steps that will be undertaken. Every stage of a tank relining process has a quality assurance check to ensure that this stage has been completed to the standard required. Tank linings are often protecting key assets in demanding environments and the cost of failure is significant.

By identifying this quality assurance steps at the proposal stage the client becomes informed and can be involved in the process to give them assurance that they are achieving the best possible return on their investment in a new tank lining

Before works can commence on site a detailed plan of how the tank lining project will be undertaken must be developed. This includes but not exclusively the following;

Safe Systems of works – Site specific method statements and risk assessments are developed to manage the hazards present during the tank lining process. COSHH assessments are tailored to each project to accommodate how coatings materials are to be employed. For example by spray applying even solvent free materials a new hazard is introduced compared to brush and roller application. Many of the tank linings we apply contain components which present an occupational health risk which needs to be managed to ensure the health of the tank lining applicators.

Quality – each tank lining project has a tailored quality assurance plan, identifying all the checks and hold points that need to be undertaken to comply with the tank lining manufacturers instructions for use.

Material Storage – tank lining materials have to be stored at defined temperatures, something that is often over looked. In winter months this may include the provision of heated stores. Tank lining materials often contain hazardous components, meaning that materials need to be stored in bunded containers in the event of spillages occurring.

Resource Allocation – ensuring that the correct people and equipment are in place to ensure a successful tank lining installation.

When it comes to undertaking the tank lining works adhering to the pre defined proposal and planning is essential. This can be challenging if factors outside of the applicators come into effect – such as weather risk or an unforeseen change in the working environment.

When changes in the developed plan occur communicating this changes to the client is critical as these can often have implications to safety, quality and program duration if not addressed. Adaptability when changes occur is something that we pride ourselves on. When changes and challenges do occur it will often involve referring back to technical documents or communication with the tank lining material supplier to understand what mitigation measures or additional steps need to be put in place.

Any change in scope are often identified as part of the testing and inspection regime developed for that particular tank lining installation. These would typically include the following;

Cleanliness – contaminants from the tanks usage if they have been in service must be removed before preparation for the new tank lining can commence. For example if a tank has been used for storing oils or hydrocarbons these must be washed away and the thoroughness of this checked using a UV Blacklight.

Surface profile – the majority of tank linings require a minimum surface profile or roughness to ensure optimum adhesion of the new tank lining. This must be checked, typically either using a surface profile needle gauge or Testex tape. This results are recorded and retained as part of our standard tank lining quality assurance.

Visual Preparation Standards – As per ISO 8501-1 there are internationally recognised preparation standards that are referenced by the tank lining manufacturer for their materials.

Soluble salts – something many tank lining contractors over look as soluble salts cannot often be seen, but an essential part of a thorough tank lining application. Soluble salts if left in place can cause premature tank lining failure through osmotic blistering as a result of moisture being drawn through the coating film as a result of osmosis.

Dust tape tests – following preparation a cleaning stage is undertaken, typically vacuuming or a washing operation. To verify that this has been effective a dust tape test is conducted at various locations throughout the tank and retained as part of the quality assurance records.

Climatic Monitoring – the tank lining manufacturer will specify the temperatures, relative humidity and dew point restrictions relating to their tank lining material. This need to be strictly adhered to in order to ensure adhesion and proper performance of the tank lining. These conditions are continually monitored through the tank lining application phase.

Wet film thickness checks – during application of most tank linings the applicator checks that the material is being applied to the correct thickness using wet film thickness combs. This is not possible with ultra fast gel time tank lining materials such as polyurea tank linings.

Dry Film thickness checks – the cured tank lining thickness is checked after each coat in order to inform the applicator if they need to adapt their methodology. These are logged and retained for the project quality file. Any areas below the required thickness must be rectified to ensure that each constituent layer is applied inline with the tank lining manufacturers technical documentation.

Porosity – a single pin hole in a tank lining is a point of failure through which moisture, oxygen and chemicals can attack the substrate you are protecting. To identify these on conductive substrates (metal and concrete) it is best practice to test the new lining using a DC Holiday Detector – commonly called a spark tester.

As well as the testing regime there are best practices when physically applying the tank lining. These include;

Stripe Coating – applying an additional coat to angles, edges, nuts and bolts where tank linings naturally are thinner as a result of gravity and surface tension of angles and edges.

Contrasting colours – it is best tank lining practice to apply each coat in a contrasting colour to the previous coat in order to ensure full coverage for each layer of the tank lining specification.

When plural spraying using fast setting materials such as polyurea tank linings the lining may be applied in multiple layers, but these are not typically considered separate coats so the same colour is used throughout.

Once the on site tank lining application works have been completed all of the quality assurance records are collated and retained for the project completion file. Any warranty documents issued and a customer feedback from completed to ensure satisfaction with our performance.