Poly Eurathane paint

I'm a mechanical engineer and have worked with design of urethane dispensing machines. What i can tell you about urethane is that its great stuff with in certain applications. One use is auto mobile restoration, but you can only bond this to rusted scaly steel. It does not bond well to clean bare steel. secondly it is sensitive to UV light, it will start to brake down the chemical composition. Now this just an opion of mine, one would need to inquire about the use of urethane paints to a chemist for each application. One ther thing, some people are/can be allergic to the Urethane paint/material when they come in contact with it on the skin, it can cause a rash like situation.

Bassically polyurethane are topcoat paint, even if there some DTM (Direct To Metal) it always a good idea to protect the steel using a primer. the best system are zinc rich primer, an intermediate epoxy and finish coat is a urethane. There's aromatic an aliphatic urethane you can use. In civil structure, you will choose your system accordingly to the type of environment it will be. A good example would be using ISO 12944 standard:

ISO 12944-2 Classification of Environments

Covers the corrosivity of various environments and how these can be measured. Various anti-corrosive systems can then be specified for these environments.

ISO 12944-3 Design Considerations

Deals with best practices in structural steel design from a corrosion prevention viewpoint.

ISO 12944-4 Types of surface and surface preparation

Covers surface preparation - reference to ISO 8501, IS0 8502, IS0 8503, and ISO 8504.

ISO 12944-5 Protective paint systems

Typical paint systems by generic type for a given durability in a given environment.

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