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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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