ST9801-CS010522 MAY-~-2001 09:33 FN! DALLAS _ P.O1
170~ - '~rKet St., ~,5OO~ LB51, Dallas, Texas 02-;~0131
214/~,~)-2500 FAX 214/920-2565 5"~-
FREESE ' NICHOLS
FAX TRANSMITTAL SHEET
Architecture To: Mike Martin Date: May 22, 2001
Company: City of Coppell
Construction Management
Dams & Spillways Fax No.: 972-304-3570 Pages: 2, including
this cover sheet
Drainage
From: ScottMaughn Charge: CPL98447 4.1
Electrical Engineering
Environmental Science
If there is a problem receiving any pages, please call Scott Maughn at
Fire Protection
Flood Management
Comments:
Levees & Canals Mike,
MechanicalEngineering I fom/arded the info on the coatings to our Vice President of
Pipeline Design Construction Services, Coy Veach, and I've included his response
and input with this fax. He explains the info in very good detail and
Plumbing Design references the NCTCOG specs. If you need more information or
input, please [et me know.
Pump Station Design
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DOCUMENT2
Scott Mau~hn
From: Coy Veach
Sent: Monday, May 21, 2001 9:27 PM
To: Scott Maughn
Subject: Coppell Rail
Scott
I can see why the contractor would want to galvanize the rail instead of painting it after reading the NCTCOG specs.
NCTCOG Item 2.9 does not tell which coating to use for metals i.e.. it provides technical data on a smorgasbord of
pigment and resins, but no paint schedule that indicates specific uses for the products listed, except for the pavement
coatings which do not apply. The proposed coating is a solvent based acrylic coating which does not appear as one of the
specified systems, so the proposed material does not meet the specifications of Item 2.9.
The project specification references installation of the rail per Item 8.12. Item 8.12 requires painting of non-galvanized rail
per Item 8.9. Item 8.12 specifies the use of Red Lead primer and aluminum coatings. Aluminum coatings do not come in
green, ttem 8.9 refers back to Item 2.g for materials, but does not specify pigment or resin and it does not appear that
pigment or resin for aluminum paint are covered in Item 2.9. The reference to item 2.9 is contradictory to the reference to
Item 8.12 again. The responsibilities in Item 8.9 placed on the Owner make it easy for any contractor to blame the City
for poor workmanship. Wonder why I dislike the NCTCOG specs.
Down to the nuts of the matter. The contractor has a choice between providing a steel rail primed with lead primer and two
coats of aluminum paint (which doesn't meet the desire for "green') or p~inting a steel rail green per a spec that does not
specify a coating type. { do not have the drawings, but assuming that we are talking standard highway guardrail, it was
probably difficult for the contractor to find this not already galvanized. The galvanizing can be blasted away, but there may
not be an adequate gauge of steel left after the process. The logical solution is to paint the rail.
The coating proposed by the Contractor is a Sherwin Williams product. We do not specify Sherwin Williams for anything
besides architectural coatings because of my impression that they require more surface preparation than their competition.
Sherwin Williams has been trying to get into our standard spec for years and they haven't made it yet. The key
characteristics needed in the product that is to be applied to the galvanized surface is its ability to "passivate" the
galvanized coating, to adhere to the galvanized surface and provide a substrata for the finish coat. Finish coatings have
not been proposed, but we need to make sure they are compatible with the material applied to the galvanized surface as
the "bond coat". Urethane and epoxies will chalk and probably need an acrylic topcoat. Since this materials is an acrylic,
I would think the green topcoat will be as well.
Typically the galvanized surface has to weather to provide some pitting that wffl allow an anchor profile to be developed. A
good anchor profile is required to give the coating something to hang onto (hand holds for the coating). I noted that the
surface prep notes for the Galvite HS requires that new galvanized metals be allowed to weather for what appears to be a
minimum of 5 months (my fax copy was a little difficult to read.) If the rails have been in place for a while they may be
okay. If they are new, it isn't acceptable. The solvent cleaning required may also be difficult to do if the rails are in place.
A test patch for adhesion is recommended. A brush blast may be used to clean the surface (also builds a profile) in lieu of
the solvent cleaning. I would recommend a brush blast be used to clean the surface and build a better profile for
adhesion. Attempts to remove all galvanizing may damage the material so that is not recommended. A high solids
material is going to give more abrasion resistance, which will be important if the rail will be bumped, skateboarded etc.
This appears to be okay (again hard to read) if it is at 80% or above. This will also help the coating wrap around the edges.
The paint spec calls for two coats at about 3 to 4.5 dry film thickness per coat. Don't settle for just one coat. Again
surface prep between coats is critical. Blasting may create some environmental hazards regarding grit and waste metal
that the contractor should be responsible tot.
This product appears to be okay, provided that the contractor doesn't give a brush to someone and just tell them to paint
the rail with this stuff. You also need to look at the surface prep for the top coats, which may require more surface
roughening or special cleaning. Unless your talking about a lot of rail, i'd take it off and send it to a shop.
817-735-7222
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TOTAL P.02