Acid Water Process Tank RefurbishmentMultiple coating failures and severe pitting corrosion in a failing storage tank
Solvent Free Tank Lining Solutions
Abfad Ltd was appointed to refurbish a 250 cubic meter process water tank for one of our Power Generation clients. Due to the condition and breakdown of the existing coating corrosion had taken hold. Severe pitting corrosion of the tank was evident with the existing coating delaminating and cracked in many areas.
The Process Water Tank in question has a wide range of chemical fluctuation. It ranges from pH 1 right up to pH13, although the tank operating range would be at pH 6-9 for discharge the majority of the time.
This particular tank was open topped so a scaffold roof was installed prior to blasting operations. Abfad Ltd supplied all plant including a shot blast dust extraction unit and expended grit vacuum system to remove grit from the tank into skips for waste disposal.
The tank walls were blasted from an internal scaffold tower. The existing coating was removed and a blast profile of over 140 microns was created. This ensures good adhesion of the solvent-free coating. Corrosion pitting was also filled during the coating application.
Solvent-free coatings offer optimum protection and performance
A solvent free, two component polycyclamine cured lining system utilising advanced epoxy novolac technology with flake and fibre reinforcement was chosen as it has superb chemical, assorted acids, and water resistance.
Once wall sections were coated all areas were inspected for pinholes or any discontinuities in the coating and these were repaired.
The floor area was then blasted and the coating applied. Coating inspection was carried out and any discontinuities in the coating were repaired. The nominal thickness of the coating was 1000 microns (1mm), this was all verified by paint inspection equipment.
All areas of the internal tank were blasted and coated including hatch ensuring full protection of tank steel.
Abfad always look to save our clients money whenever possible
On this project, our client also requested emergency safety cover for other trades working in confined spaces as well as the tank refurbishment.
To save costs for our client Abfad Ltd supplied a three-man emergency safety crew and a three-man blast and coating crew. Safety crew was on site and available to support Alstom trade personnel during confined space entry and also available to assist with the tank refurbishment when required.
This was possible as most Abfad personnel are multi-discipline. Trained in rope access rescues in addition to specialist coating activities. In real terms, the cost of the tank refurbishment was half price, therefore, saving our client thousands of pounds.
Work consisted of:
1. Temporary scaffold roof was installed, along with internal scaffold tower
2. Tank walls and hatch were blasted to SA2.5 standard providing a blast profile of over 140 microns
3. Solvent free coating applied to tank walls and hatch with a nominal thickness of 1000 microns
4. Coating inspected for any discontinuities or pin holes and any repairs made
5. Floor area blasted to SA2.5 standard
6. Solvent free coating applied to floor area with a nominal thickness of 1000 microns
7. Coating inspected for any discontinuities or pin holes and any necessary repairs made