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Continued from The
Blog, p. 13.
The following items relate to coatings & linings.
Please be advised that the items are
not peer-reviewed, and opinions and suggestions are entirely those of the in- quirers and respondents. NACE Interna- tional does not guarantee the accuracy of the technical solutions discussed.
welcomes additional responses to these items. They may be edited for clarity.
Paint shelf life
months—excepting products like inor- ganic zinc silicate and ethyl silicate-based UI\MZQIT[ UI\MZQIT[ KWV\IQVQVO TMIÅVO aluminum, etc. One should always go by the manufacturer's instructions. The change in the basic nature of
Q A
dimensions are 28 ft (8.5 m) in diameter NACE International, Vol. 51, No. 3
Q
the paint again depends on chemistry. Changes in consistency and thixotrophic properties, along with settling in high- pigmented versions, are normal occur- rences. Paint revalidation can be done in most cases, excepting inorganic zinc-rich primers, but it is always wise to get advice from the manufacturer.
Storage tank protection
We are going to install a new water storage tank (a standpipe) in a seismic zone. The tank
March 2012 MATERIALS PERFORMANCE 41
I have three questions: z How is a paint's shelf life decided?
z What basic properties of paint would change on
expiration of shelf life, and how do they affect paint performance?
z Can expired paint be revalidated after analyzing the properties that are prone to change?
Shelf life of the paint depends on its characteristic nature and chemistry. For most generic paints, this is generally 12
and 85 ft (26 m) in height. One option is to construct a steel tank and another is to construct a prestressed concrete tank. I would like to know if we should go
with a prestressed concrete tank with coating outside and without coating inside, or a steel tank with coating on both the inside and outside. Assume that there is no cathodic protection (CP) for the prestressed concrete tank and CP for
the interior of the steel tank. What are the pros and cons to these systems?
A
I would strongly favor a steel standpipe. The long-term suc- cess of the coatings is going to be QVÆ]MVKML PMI^QTa Ja _PM\PMZ
the surface preparation and cleanliness are appropriate. Of course, proper
Continued on page 43
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