Specialist Lining Services were called in to carry out a re-lining of a 61m² Water Production Tank at a company based in Ulverstone, Cumbria. The tanks were suffering from catastrophic coating failure due to poor adhesion from the epoxy to an unprepared substrate. The tank was located in a sensitive location in a laboratory environment where it was essential that the area was to be kept clean as well as manageable with the odour during the lining process. Due to the sensitive area, Specialist Lining Services carried out the abrasive blasting preparation at the weekend and carried out the lining process at night to prevent hampering the company’s production.
Specialist Lining Services worked on a design of a self-sufficient temporary work tent. The tent would be used as a protection to prevent abrasive ricochet leaving the work area, whilst also acting as an extortion system to draw abrasive dust and solvent fumes to the outside. Due to the type of open topped tank, SLS utilised a scaffold tower with outriggers to act as a platform to attach out confined space safety winch. During both processes the temporary tent to its full potential on both the preparation and the lining. All machinery and the floor area were also masked to keep a completely clean environment.
At Specialist Lining Services, preparation is 90% of our work when installing a GRP lining system. For this particular tank, abrasive blasting was chosen. Abrasive blasting removes all coatings, surface additives contamination and provides an-etch for the lining to adhere to. This particular tank had a white concrete screed and a failed epoxy coating system to remove, the original concrete cast needed to be exposed in order for our lining system to adhere to the tank. The abrasive garnet was chosen due to its hard angular and low dust levels for this particular application. Once the blasting was completed, the tank was completely cleaned out and dry vacuumed and ready for the resin prime.
Specialist Lining Services’ operatives then primed the concrete using Isophtalic Resin to seal it. Priming also aids in the absorption of the resin in the substrate when carrying out the lining system. The primer took a few hours to cure. Whilst the operatives waited for the resin primer to dry, they cut out the chopped strand matting and the chemical resistant tissue to size for the glass reinforced plastic lining system.
SLS then began laying two layers of 450csm mating to the tank, this was embedded in an Isophtalic Resin. The first layer was overlapped 50mm to create a reinforcement of the GRP System. The second layer of CSM was staggered and was laid up edge to edge to create a seamless finish to the lay-up. The entire matting lay up was allowed to dry before application of the next stage of the system.
Due to the high chlorination of the water the tank would be holding, it was of upmost importance to protect the matting system by using more chemical-resisitant resin. Vinyl ester resin was chosen due to 100% resistance to chlorine. The tank was hand sanded using 80 grit sandpaper to remove any imperfections in the matting system. The operatives would then wet the wall using vinyl ester resin before carefully applying the chemical resistant tissue to the walls of the tank. The floor was then coated with a flood coat of vinyl ester to protect the matting on the floor area. This was allowed to dry over a 4 hour period before the next stage.
The water storage tank was suffering from coating failure due to a screed being applied to the walls which created no adhesion for the epoxy to adhere to, the floor however, was bonded due to the screed not being applied to the area. SLS would have to carry out abrasive blasting to remove the existing screed, failed epoxy coating and reveal the existing concrete substrate in order for the new glass-reinforced lining system to adhere to permanently. Due to the sensitive location, the operatives had to concentrate on creating an excellent extraction system to remove solvent fumes and dust during the abrasive blasting.
SLS operatives made a confined space entry to the tank using a ladder whilst attached to a fall arrest system, two PASMA trained operatives would install a scaffold tower which would be used to gain access to the tops of the walls for both the blasting and lining of the tank. SLS created a self-contained work tent with an extortion system to create a vacuum to extract the dust created to an outside exhaust point to protect equipment in the building from damage. Once the abrasive blasting was completed, the SLS operatives would clean all the abrasive up and remove the work tent completely, ready for the lining.
The walls and floor were initially primed using an ISO resin and allowed to cure. The SLS operatives then applied two layers of 450csm matting in ISO resin to the walls and floor and left to dry. The operatives would then sand out any imperfections using sandpaper before applying a layer of chemical resistant tissue using a Vinyl Ester Resin to protect the matting from the chlorine. Once the vinyl ester tissue lay-up had dried, operatives would then sand out any imperfections before preparations were made for the next stage. SLS worked out of productions hours to not hamper the factory’s own works.
Specialist Lining Services’ operatives used pigmented vinyl ester resin with RAL 5012 and applied this to the walls using rollers and brushes. This coat ensures no pinholes are left on the lining system whilst also further protecting the matting and tissue lay-up from the chlorine that is to be added to the water. Specialist Lining Service operatives allowed this coat to dry before thoroughly sanding the tank to create adhesion for the final specialist gel coat to adhere to. Specialist Lining Services operatives removed the dust created from the sanding process and prepared the roller brushes and gel coat for the final stage.
The final NPG specialist gel coat was applied using rollers and finished with a large brush to give an even finish to the tank. The NPG gel coat offers an excellent smooth finish whilst offering the necessary chemical resistance for the chemicals added to the water to keep it hygienic. The whole lining system was given Specialist Lining Services’ 15 year guarantee against osmosis and delimitation. The new system installed gives the client piece of mind against water leaking out of the tank whilst also giving the concrete substrate improves structural integrity. Cleaning of the tanks can be cleaned by simply hosing or sponge washing the lining system.
The whole project was a complete success from start to finish done completely on schedule, our operatives were courteous and ensured that protecting the factory’s premises was at the forefront of their minds whilst working. Before leaving the project, our operatives even got the floor scrubber out and dusted down the work area completely before removing all of the equipment and handing back the talks to the client.
Continuing with the protection of the matting and tissue lay-up, a vinyl ester resin coat pigmented in RAL 5012 was applied by rollers to give the tank a colour and also further protect the matting from further osmosis due to chlorine. Once the coat had dried sufficiently, SLS operatives would sand the entire tank using handheld sanders to create adhesion for the final gel coat.
A specialist NPG gel coat with a high chemical resistant to chlorine and many other chemicals were used. This was applied by rollers and finished with a brush to give an even finish to the tank. The tank was then post cured using a heater before refitting tank furniture.