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What exactly is a visco-elastic coating?
A viscous elastic coating or to speak in ISO 21809-3: 2016, chapter 13 erminology : a non crystalline, low viscosity, amorphous polymer bases coating is based upon a material that shows both elasticity (stretch) and viscous (flowable) behavior. The material will show some viscous cold flow, and has adhesive properties based upon van der Waals interaction with the surface. Due to the viscous component of the material, a complete wetting of the surface takes place. When for instance overlap takes place during application, the layers of the product will flow to become one continuous coating. The elasticity of the product ensures a layer thickness, peel strength and resilience against movements.
Why is a visco-elastic coating better than a conventional coating?
Every coating has it drawbacks and advantages. Therefore it is not possible to say that one coating is better than the other. What makes VISCOTAQ unique is the ease of application in the field as it eliminates many of the issues that are hazardous in field applications like a critical surface preparation, application failuers, presence of salts and bacteria and issues with CP. Unlike for instance with tapes, a continuous homologue layer of coating is favorable to prevent spiral effects. The adhesion is created on molecular level, such that water cannot penetrate between the coating and surface. Salts have impact on spray applied coatings, where VISCOTAQ is not adversely influenced in its performance by salts.
What distinguishes VISCOTAQ from other visco-elastic coatings?
VISCOTAQ is an non crystalline, low viscosity, amorphous polymer based coating.It does not use any butyl or rubber type components but is amorphous. VISCOTAQ is a solid material, therefore stable, once applied. Other viscous elastic systems are fluid type materials and therefore are continuously in a dynamic phase. It is possible that under elevated temperatures and/or under an angle at soil to air transitions, these coating may show some sliding, dripping or sagging.VISCOTAQ does not. The reason is the melting point at 152,9 C and a true yield point at elevated temperatures.
How does self healing of VISCOTAQ works?
The elastic component creates a memory effect during damage while the viscous component create some flowing properties. Let’s say somebody punctures the coating. The outerwrap has some tension around the product and enough to create the flow: the material oozes out of the pinhole and the repair is automatically made.
What surface preparation is minimum required for VISCOTAQ?
The minimum surface preparation is SSPC2, by preference SSPC 3. The recommended surface preparation is SSPC 10.
Can we use VISCOTAQ as a repair material?
VISCOTAQ has been designed as a coating repair material and adheres to almost any surface, provided it has been properly cleaned. Viscotaq has not been designed for repairing pipelines with wall losses.
What does it mean that VISCOTAQ has a yield point?
A yield point is the point where the viscous component starts to overrule the elastic component. At this yield point the material starts to flow.
Can unequal coating thicknesses occur with VISCOTAQ?
No, also not at elevated temperatures. Unlike other viscous elastic materials, VISCOTAQ is formulated to have a uniform layer thickness around the pipe under normal circumstances. This is the advantage of a solid material and having a true yield point.
Can we use a wrapping machine with VISCOWRAP ?
Yes you can although it depends very much upon the situation in and near the pipeline trench(es) if this will help you to improve the speed of operation. In case of bell holes one may consider to wrap by hand as one may have several teams wrapping at the same time in different bell holes. With a wrapping machine one needs to change rolls and one needs to move the machine from one bell hole to another and these actions also require time.In case of a continuous in one trench a wrapping machine might be advantageous although we think one should consider this only for longer distances.
Can we wrap VISCOWRAP over the ditch and place the pipeline in the trench?
Yes you can. VISCOWRAP does not need any curing and is a "pret -a-porter" product.. The best way is to lift the pipe by slings and consequently lower it into the trench. In this way you avoid coating damage as much as possible. In case of long distance transportation VISCOTAQ Rockshield Protection is available for protection the coating.
Will the adhesion of VISCOTAQ products increase over time?
Yes. Although VISCOTAQ products can be considered as a solid, the material has a cold flow and wetting characteristics and will penetrate the pores of the substrate. The bond of VISCOTAQ material increases over the time. VISCOTAQ will always show a cohesive fracture, which means that when the material is peeled off, the material will break apart and leave a corrosion protective layer on the pipe. In this way one has always the guarantee of corrosion prevention which makes VISCOTAQ so unique.
How are VISCOTAQ products packed?
Every carton of VISCOTAQ material has a batch number indicating among others (but not limited to) the date of production and the batch where it has been produced from. Viscotaq cartons are double wall cartons. All cartons are packed on pallets with side stacks and sealed into seaworthy pallets. Pallets can be stacked in a 20’or 40’container. Of each roll shipped the date of production and production details can be retrieved.
Is VISCOTAQ a patented product?
Yes. Viscotaq has applied for several patents which in the meantime have been awarded in numerous countries and regions.
Will VISCOTAQ show an immediate adhesion?
Yes, but this depends on the ambient temperature and the type of VISCOTAQ material. The higher the temperature the quicker the tack. As a solid the adhesion process is different from a typical fluid but at the end the adhesion of VISCOTAQ is unrivaled due to the design of the material - which can be explained by specific rheological models – and due to the low surface tension.
When can we do a peel test with VISCOTAQ after we wrapped a substrate and what can we expect?
You can expect a cohesive fracture. Officially a peel test should be done after 7 days according to ISO 21809-3:2016. In case this is not possible we advise you to wait 72 hours before doing such test as VISCOTAQ needs a certain time to completely adhere to the substrate. Once adhesion is obtained it is not possible to peel VISCOTAQ off the substrate.
Will a pipeline protected with VISCOTAQ ever corrode?
There may always be unforeseen circumstances like earthquakes, unknown or unforeseen chemicals in the ground, earth slides, natural disasters, change in operating parameters, unforeseen soil stress that can cause a change in the underground conditions. And nothing lasts forever. But under normal unchanged circumstances there will be no presence of moisture and hence corrosion is very unlikely.
What does the 40 years warranty exactly means?
It means that once applied the VISCOTAQ viscous elastic coating system will not show any chance in performance as we are facing an inert, continuous water impermeable and stable system. It means that after 40 years the corrosion preventive characteristics are the same. The material does not deteriorate and will not crack, becomes brittle or show more moisture or gas permeability in the course of time. So it is a guarantee for the performance of the coating. It does not mean that corrosion can never happen as there may be unforeseen circumstances that occur later like earthquakes, landslides, unknown or unforeseen chemicals in the soil et cetera. The warranty guarantees that if the coating performance decreases new coating material will be supplied free of charge. The coating however should have been applied according to VISCOTAQ’s instructions. Examples of these requirements are for instance a surface preparation according to the manufacturer’s instructions, trained and certified applicants, continuous inspection and testing of the application by a certified VISCOTAQ INSPECTOR. For more details about the 40 years warranty please contact Edwin Welles on firstname.lastname@example.org or Leo van Beugen at email@example.com.