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INITIAL REPORT STOPPING CORROSION On the underside of a truss bridge in By High Pressure (5,000 psi) and Overcoating With the Termarust High Ratio Co-Polymerized Calcium Sulfonate Coating System
For Near Cleaning & Coating by Corrosion Protection, Inc.; Coating Materials from Termarust Technologies, Project Painting Date: August,
2008 INITIAL REPORT
By: Craig A. Ballinger, P.E., Termarust
Technologies Phone: 888-279-5497 [then
press 4] Email:
cballinger@termarust.com OVERVIEW This report provides some
information and photos on the cleaning and Termarust coating that was done on this
bridge, in August 2008, for The primary objective of
this project was to stop structure critical corrosion on the structural
steel members on the underside of the bridge that support the deck. The corrosion on the upper portions of the
trusses was not considered critical, and because of limitations in available
funding, they were not cleaned and coated with the Termarust materials. The Termarust coating
system was selected because of the 15+ years of field-proven history of the
Termarust system to chemically stop active corrosion (including in connections
and bearings) with only minimal cleaning (mainly) with a 5,000 psi pressure
washer. The cost for this project
would have been considerably higher (perhaps double) if sandblasting and
application of a traditional 3-coat, zinc-based, coating system would have been
required; which does not have the chemistry to stop active corrosion; including
in connections and bearings. The project involved: Stopping
structure-critical corrosion on the underside of the bridge ·
Cleaning
and Termarust coating of the structural steel members that support the deck
including the lower chord members of the truss.
Only the lower 3 ft of the vertical truss members were cleaned and
coated. ·
Retrofit
strengthening of the ends of four of the longitudinal members under the deck;
where corrosion had caused large holes in the webs. These areas were strengthened with steel
plates that were bolted to both sides of the webs. (See Photos 4, 15 and 16) It is
important to note: Containment of corrosion debris and paint chips was
not required, because the existing paint did not contain lead. Shown below are references and procedures for
cleaning and painting, and pictures of cleaning and painting of the bridge. REFERENCES Contact Person: Eugene Triplet Painting Contractor Corrosion Protection, Inc. Contact People: Aaron Long or Mark Preusser CLEANING AND APPLICATION PROCEDURES The following Termarust
standard procedures were specified and followed: 1. Pressure wash clean the bridge members with
a 5,000 psi pressure washer (at a 6 standoff distance) with clean water, from
the stream. (Photo 5) 2.
Heavy
scale rust was removed using wet abrasive blasting, with sand in the water.
(Photo 9) 3. After cleaning a final rinse was done
with the 5,000 psi pressure washer with an additive of Chlor*Rid in the water
to remove non-visible salts; e.g. chlorides, that contributed to the corrosion,
including under the scale rust. (For
more information on Chlor*Rid see www.chlor-rid.com) 4. With dry compressed air blow dry all
connections between steel members. 5. Apply Termarust TR2200 Penetrant into
all open connections; especially where there is crevice corrosion and pack
rust. 6. Apply a 10 mil DFT caulk (or stripe)
coat of Termarust TR2100 Topcoat into open connections; where there is crevice
corrosion and pack rust; on top of the TR2200 Penetrant. 7. Spot prime areas of bare steel and
tightly adhered (contaminant free) rust with 5 mils DFT of Termarust TR2100
Topcoat 8. Overcoat the entire area with another 5
mils DFT of TR2100 Topcoat. 9. Note:
after cleaning and coating the ends of the four longitudinal beams (with
corrosion caused holes in the webs) steel plates were bolted to both sides of
the webs. The inside of the steel
plates were coated with Termarust before they were installed, and the outside
of the plates were coated after installation.
(Photos 4, 15 and 16) It is important to note
that steps 5 through 8 may be done immediately after each other; i.e.
wet-on-wet; which is why the Termarust system is considered to be a One Coat
system. The final result was: ·
5
mils DFT (Dry Film Thickness) on tight paint, ·
10
mils DFT on bare steel and tight rust, and ·
20
mils DFT over connections. PICTORIAL OVERVIEW The following pictures provide a pictorial overview
of the project.
Photo 1 Side view of the truss. Note the corrosion on the upper
portions of the truss were considered not critical, and for economic reasons
they were not cleaned and coated.
Photo 2 All members supporting the deck have
serious corrosion problems.
Photo 3 Close-up of one of the transverse beams and
connections.
Photo 4 The ends of 4 stringers had holes in the
webs equal or larger than this
Photo 5 Water for washing came from the stream, was
put into the yellow settling tanks.
Clean water was then moved into the white plastic tanks to supply the
pressure washer.
Photo 6 A rolling scaffold platform was used to
access the underside of the bridge.
Photo 7 A tarp was installed under the platform
Photo 8 A 5,000 psi pressure washer was used to
remove loose paint and loose rust.
Photo 9 Scale rust was removed using 5,000 psi
pressure wash with sand abrasive,
Photo 10 Close-up of beam ready for painting
showing tight clean rust and tight paint.
Photo 11 Two of the transverse beams have been
painted, one is clean and ready for painting.
Photo 12 Painted end of a transverse beam showing
where corrosion had thinned the web.
Photo 13 Three of the transverse beams that have
been cleaned and coated with Termarust.
Photo 14 End of a beam and the gusset plate have
been coated with the Termarust system.
Photo 15 One of the four beams that repairs were
made on. The end of the beam had been
cleaned and coated, as had the inside surfaces of the reinforcing plates (on
both sides of the beam)
Photo 16 The outside surface of the reinforcing
plates were coated after installation of the plates.
Photo 17 Only the lower chords of the truss and the
lower 3 of the vertical members were coated.
Photo 18 The project has been completed, supports
for the platform will be removed. |
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