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UPDATE REPORT
AFTER 3 YEARS STOPPING CREVICE
CORROSION High Pressure (5,000 psi) And Overcoating of a historic (1879)
Bollman bridge over the With the
Termarust high ratio co-polymerized calcium sulfonate coating system
For the Through the Federal Lands Division, Cleaning & Coating by Titan Industrial Painting, Coating Materials from Termarust Technologies, Project Painting Date: January,
2006 UPDATE
REPORT AFTER 3 YEARS By: Craig A. Ballinger, P.E. Termarust Technologies Phone: 888-279-5497 [then
press 4] Email:
cballinger@termarust.com OVERVIEW This report provides some
background information and information and pictures on the cleaning and
painting portion of work that was done on this bridge, in January 2006, for the
National Park Service, under a FHWA contract. The bridge is a historic
1879 Bollman truss bridge, over the The project involved: ·
Removal
and replacement of the timber deck ·
Removal
of the longitudinal timber floor beams and replacement of them with four heavy
steel beams, that span from abutment to abutment; i.e. the beams will carry all
vehicular loads the truss remains as a historic (non-load carrying)
structure. The visual appearance of the
bridge will (essentially) not be changed. ·
A
painting subcontractor pressure wash cleaned the truss and applied the
Termarust coating system after the General Contractor did some structural
repairs to the truss floor beams. The contract required: 1.
A
high ratio calcium sulfonate coating system from either Termarust Technologies
or CPC. 2.
A five-year
warranty against coating system failure; including crevice corrosion and pack
rust. Shown below are references and procedures for
cleaning and painting, and pictures of the bridge and the cleaning and painting
operations. UPDATE OBSERVATIONS OF THE MAY 12, 2009
SITE VISIT
On this date the bridge was
visited to look at the condition of the Termarust coating and whether the
crevice corrosion had been stopped. Photos No. 21 through 28
provide an overview of what was observed, and are summarized below: 1. The Termarust coating appears to be in
excellent condition no undercutting or delamination. 2. There were a few areas (not shown)
where the Termarust coating had been scratched or marred during installation of
the timber deck and rub-rails; however this damage to the surface of the
coating has not (and will not) lead to failure of the coating; i.e.
undercutting and delamination. 3. In summary, the Termarust coating is in
excellent condition and crevice corrosion is stopped. REFERENCES Markus Miller Bridge
Project Manager Phone: 703-404-6252 Painting
Subcontractor Titan Industrial Painting, Contact Person: Pete Forakis CLEANING AND APPLICATION PROCEDURES The following Termarust
standard procedures were followed: 1. Pressure wash clean the bridge with a
5,000 psi pressure washer (at a 6 standoff distance) with clean water with an
additive of Chlor*Rid to remove non-visible salts; e.g. chlorides. (For
more information on Chlor*Rid see www.chlor-rid.com) 2. With dry compressed air blow dry all
connections (and cross-over points on built-up lattice members. (almost all
superstructure members) 3. Apply Termarust TR2200 Penetrant into
all open connections 4. Apply a caulk (or stripe) coat of
Termarust TR2100 into/onto edges of connections 5. Spot prime areas of bare steel and
tightly adhered rust with 5 mils DFT of Termarust TR2100 6. Overcoat the entire area with another 5
mils DFT of TR2100. It is important to note
that steps 3 through 6 are 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 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 Bridge, and approach span, in 2005, before
painting.
Photo 2 Memorial plaque on bridge: 1879 W. Bollman
Photo 3 Underside of the bridge showing transverse
floor beams and longitudinal timber beams
Photo 4 Edge of front truss member with crevice
corrosion and pack rust that has bent the cover plate and stressed the
rivets.
Photo 5 Close-up of pack rust that has bent the
cover plate.
Photo 6 Closer view of the pack rusted connections.
Photo 7 Upper tie-rod and truss connection.
Photo 8 Bridge is covered with a tarp, for cleaning
and painting Note: a barge in the Canal provides a working
platform and containment.
Photo 9 Removing scale rust before pressure washing Note. Scale removal was started with hammers and
later with small air tools.
Photo 10 5,000 psi pressure washing of the truss,
with Chlor*Rid in the final rinse water.
Photo 11 A large heater was used to maintain a
minimum 50oF steel temperature for
painting.
Photo 12 Applying the TR2200 Penetrant into
connections.
Photo 13 TR2200 Penetrant has been applied to front
bearing connection. (Excess Penetrant was then removed by brush)
Photo 14 TR2200 Penetrant has been applied to the
connection, before application of the TR2100 Topcoat.
Photo 15 The connection has been coated with the
TR2100 Topcoat.
Photo 16 TR2200 and TR2100 has been applied to the
connection after it was strengthened, (See Photo 10)
Photo 17 The truss has been painted and the new
longitudinal beams have been installed. A new timber deck will now be installed
Photo 18 Painting completed.
Photo 19 Close-up of connection with most of the
pack rust removed before painting.
Photo 20 Close-up of connection with most of the
pack rust removed before painting.
Photo 21 May 12, 2009 View of completed bridge
work
Photo 22 May 12, 2009 No coating or corrosion
problems.
Photo 23 May 12, 2009 Crevice corrosion has been
stopped.
Photo 24 May 12, 2009 Corrosion has been stopped.
Photo 25 May 12, 2009 Corrosion has been stopped.
Photo 26 May 12, 2009 No coating or corrosion
problems.
Photo 27 May 12, 2009 No coating or corrosion
problems.
Photo 28 May 12, 2009 No coating or corrosion
problems. |
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