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Tank Lining Warranties: Don't Believe the Hype

The difference between an expense and an investment is how well it pays you back over time – the longer the asset continues to perform as required, the better an investment it has been. A warranty is designed to protect an investment and Michael Harrison, global product director for linings at Sherwin-Williams, explains why they should reflect reality and have genuine value.

A warranty is a formal assurance, typically in writing, that certain conditions will be fulfilled, especially that a product will be repaired or replaced if not of a specified quality. Over the last 20 years or so we’ve become used to seeing coatings and linings manufacturers issuing warranties in order to highlight the effectiveness of their products and give customers confidence in their purchasing decisions. 

Tank lining warranties vs life expectancy

Any coating or lining will have a limited service life and inevitably degrade. Its life expectancy is typically the interval from when the coating is applied to when it is no longer offering the required protection. A life expectancy may be 30 years, but a warranty is usually not this long, with most manufacturers offering them over a 5-10 year period. 

ISO 4628-1:2016 is often used as a reference point for warranties, as it defines a system for designating the quantity and size of defects and the intensity of changes in appearance of coatings and linings. It outlines the general principles associated with the quantity and size of any defects, defines the intensity of changes in appearance and outlines the guiding principles used to undertake assessments.

Guaranteed levels of corrosion protection

Within this standard there are defined levels of corrosion – Ri0-Ri5. For example, if a corroded area has individual spots between 0-5mm and 5mm it is considered to be Ri3. Areas graded Ri1-Ri3 will require patch repair coating, while with corrosion grades Ri4 and Ri5, the corrosion protection capacity of the coating will have corroded to a degree that will require the structure to be fully recoated. 

Most warranties guarantee that after a certain number of years there will be less than Ri3 corrosion as per ISO 4628-1:2016. This may take the form of a sliding scale, where there is a certain amount of corrosion after one year up a maximum at various intervals up to the end of the warranty period. For example, 4-7 years for Ri2 and 7-10 years for Ri3.  The guarantee needs to reflect what the owner wants/needs. Usually this is a corrosion warranty – but it is important to have the discussion.

The challenges and pitfalls of tank lining warranties

Bulk Storage tanks are able to hold 7 million litres or more of fluid and any disruption to their use can have serious financial and operational implications. This means that, unless there are clear signs of corrosion, an inspection and maintenance period is usually left as long as possible. A good warranty should therefore reflect reality – if a storage tank will not be opened for 13 years then a five or 10 year guarantee is irrelevant. Also, as a storage tank is usually full it is difficult to observe breakdown as regular inspection is often not possible.

Even if a problem is identified within the warranty period, making a claim isn’t so straightforward. There will need to be inspections and assessments carried out that could take time, and a storage tank might have to be decommissioned while these take place and the matter is resolved. Supply chain issues have meant that safely and securely storing commodities such as water, wastewater, petroleum products, chemicals and food products is vital to the global economy and most owners will, understandably, just want to get the issue resolved as quickly as possible.

Protecting all parties

In reality, a guarantee may not protect the owner's asset sufficiently. If the tank is showing corrosion in the coated area, then it is no longer protecting the floor and there is a risk of leakage – with associated loss of product and potential environmental fines. Getting a storage tank lining right first time is vital and the lining quality should be set from reference area, which is then agreed and rolled out. 

Working with a technical service team that understands the customer need, both now and in the future, will mean the right questions about substrate composition and condition, exposure conditions, chemicals present and in what concentrations, as well as the temperature and pressure data are asked. Most importantly, supporting data and a demonstrable track record will ensure that the correct lining is selected to give the required performance, with qualified inspectors confirming the surface preparation and application is carried out correctly.

Bespoke tank lining warranties tailored to your needs

Rather than issuing a ‘one size fits all’ warranty, a more beneficial approach is to build a bespoke, well-designed and executed guarantee around an inspection period that is agreed with the customer. The warranty will them be relevant to the requirements of the owner and applicator. Discussions need to take place before finalising lining specifications, so all aspects of the warranty offered can be considered, such as documentation. 

This approach benefits everyone. Customers will be protected because in the event of a problem their costs are covered, while applicators will be protected because if the original warranty application was properly evaluated and assessed, they will not be liable for rectification measures. Manufacturers will also be protected because the process of checking designs and verifying workmanship will ensure the correct lining has been specified and applied correctly to maximise longevity.

Asking the right questions

Not all warranty programs are alike and rather than focusing on the length of their duration, end users need to switch their attention to the resilience and reliability of a manufacturer’s offering. Asking manufacturers the right questions, seeking testimonials and references, and comparing and contrasting what the industry has to offer is highly advisable. As with any other form of insurance, the devil is in the detail and knowing exactly what is, and what is not, covered is critically important.

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