Concrete shell heat exchanger protective coating

It has been anticipated that coatings applied on the inside of concrete surfaces of steam condensers might blister when there is a vacuum (28.5 in Hg) on the inside. A variety of coatings have been tested to see when blistering is a problem. Different coatings have been put through a vacuum test and some good results have been obtained. Two types of coating system applications can be identified: (a) ones which form tough, tenacious and solid surface films on concrete surface and (b) breather films which act more like semipermeable membranes. Epoxies, silicone rubbers, butyl rubbers belong to the former group while acrylic resins, styrene-butacidiene compound and silicone resin belong to the latter. Chlorinated rubbers and ordinary roof cement both blister when put under vacuum. It has also been identified that part of the blistering problem can be evaded by using proper concrete and concrete surface preparation techniques. Therefore, coatings (applications to concrete surfaces) have been found and tested such that they will not blister under high vacuum environmental exposure.