Selected Answers

From Ron Lanter of Protec on July 26, 2011:
     Spot/Sweep blast,  t ...read more      Spot/Sweep blast,  then apply a full coat of epoxy like a Carboline 890 and then come back with another full coat of 890 and walk away. You said economical. Stay away from urethane. It's expensive and over-rated, and, trust me, it will fade in this heat.

From Thomas Selby of Retired on May 19, 2011:
     Well, first test for lead ...read more      Well, first test for lead in the old coatings on the tank. Then proceed with surface prep based on your findings. Clean and remove old coatings and corrosion. Apply a barrier coat of an anti-corrosive, high-solids, thin-film epoxy. Spot prime with an epoxy mastic the bare metal areas because these areas will fail sooner. Then full coat with a two-component polyurethane. There is no economical system because the real cost is in the labor. Don't be penny-wise and pound foolish.

From Gregory Berg of AEP on May 18, 2011:
Economical system:  HPWC Spot power-tool clea ...read more Economical system:  HPWC Spot power-tool cleaning (SSPC- SP 3); touch up with  zinc-rich epoxy; and apply two coats of high-build acrylic. Common system: HPWC Spot power-tool cleaning (SSPC-SP 3); touch up with zinc-rich epoxy; apply an epoxy intermediate; apply a polyurethane or polysiloxane topcoat

From Billy Russell of D&R COATING INSPECTION on May 18, 2011:
A zinc/epoxy/polyurethane system is one  ...read more A zinc/epoxy/polyurethane system is one  recommended a lot. I have used this system a lot with great success, although there are cheaper systems out there. This system, if applied right, has a great life span. Stripe-coat the weld seems between coats for added life span.

From M Ehab of North Valley on April 7, 2012:
     There is nothing easy and ...read more      There is nothing easy and very low cost like applying 2 coats at 40 Microns DFT of aluminium-pigmented paint based on a flexible penetrating alkyd oil.

From Mike McCloud of Amex on April 23, 2012:
    Billy, I like that system, alth ...read more     Billy, I like that system, although we have used a pre-prime  instead of zinc and have tanks that are still holding up after 15-20 years.

From remko tas of Futuro SRL on April 11, 2012:
It depends on the relation of labour costs and pai ...read more It depends on the relation of labour costs and paint prices in your country. In Bolivia, where labour is relatively cheap and epoxy and polyurethane paints are expensive, for overpainting exteriors that are not yet too rusty, the best economical option would be to manually sand the surface lightly and overcoat with alkyd paint.