The scope of the project
Bio-ethanol and bio-methanol storage move into focus in tank farms with the introduction of E5 and E10 blended fuels. The bulk storage tanks for alcohols in tank farms or refineries are not only exposed to severe steel corrosion. Conventional coating and corrosion protection products are also not chemically resistant to exposure to them. Therefore, these steel tanks face internal corrosion due to the medium as well as to its vapour. But Wolftank Austria is able to provide a complete solution to floor lining in bio-ethanol and bio-methanol tanks.
The challenge
A storage tank with 20 m diameter in Central Europe was intended to be used for a bulk storage of ethanol. Wolftank Austria decided to apply the system Epoflex® 6N, which is resistant to 100 % bio-ethanol and approved as tank lining system for ethanol tanks by Germany’s national technical approval, DIBt.
The customer specified application of a 2-layer laminate system which is covered by a final Epoflex® 6N layer and an antistatic top layer. A wet- on-wet laminate application made the project very challenging. As attested by the German TÜV, this lining system exhibits structural properties and actually acts as a double floor lining (steel floor plus fiberglass floor).
The customer’s expectation was not to have any tank openings due to floor inspection for a period of 15-20 years. This was a basic requirement in the design of the layer system.
The solution / timing
The Epoflex® 6N lining system comprises the following:
- Epoflex® 6N lamination resin + bi-woven fibreglass fabric
- Epoflex® 6N resin
- Adapox® L conductive resin
Wolftank Austria recommends a clean subsurface for a proper long-lasting coating system. Therefore, Wolftank technicians sand-blasted the surface in order to achieve the proper adhesion (SA 3).
After the surface preparation, the team levelled the welding joints at the bottom of the tank with mortar (Epoflex® Klebmoertel N). The objective of this step was to get a smooth and even surface. Using the same material, the team created a corner radius between shell and annular ring.
The application of the laminate layer started the next day. This reinforcement consisted of the application of two layers, wet on wet, since the final, dried layer thickness of the lamination must reach 2,6 mm. This was the most challenging part of the implementation of the lining system since obtaining the appropriate amount of resin was very difficult. Too much resin would result in the second sheet of fibreglass floating on the first one; not enough resin would result in inadequate thickness. Subsequently, technicians applied Epoflex® 6N on the cured and sanded subsurface with an airless spraying machine. As the top layer, the team rolled the conductive layer on quite thinly.
The whole application lasted a period of 20 days leading to a minimum downtime related to the upgrade to a new storage media. It is not necessary to apply hot works and hydraulic testing after this installation. This resulted in a significant cost saving.
The outcome
Wolftank Austria team completed the project on time and fully according to the customer’s required standards (quality and safety). Since ethanol storage is increasing in Europe and other countries, this application is a great Wolftank Austria reference for future projects.
With more than 20 years of expected lifetime extension of the lining system, none additional floor maintenance is a major benefit. In addition, the low installation down time is a huge benefit too. In addition, due to the long-term chemical resistance of the Epoflex lining, no significant maintenance cost is necessary. This type of lining is not subject to corrosive deterioration.
To also learn about Wolftank Austria’s solution for methanol storage, please click here.
