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UPDATE REPORT – AFTER 19 MONTHS STOPPING CREVICE CORROSION On a Pennsylvania Turnpike bridge on I-476 (the Northeast Extension) at Mile Post 88.59 By High Pressure (5,000 psi) Water Wash Cleaning (with C*R) and ZONE Overcoating with the Termarust high ratio co-polymerized calcium sulfonate coating system
For the Pennsylvania Turnpike Commission Harrisburg, Pennsylvania
Cleaning & Coating by Titan Industrial Painting, Baltimore, Maryland
Coating Materials from Termarust Technologies, Vienna, Virginia
Project Painting Date: April, 2006
UPDATE REPORT – 19 MONTHS AFTER TERMARUST ZONE PAINTING
By: Craig A. Ballinger, P.E. Termarust Technologies Vienna, Virginia, 22180 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 April 2006, for the Pennsylvania Turnpike Commission – and updated after a site visit on November 23, 2007 – 19 months after the pressure wash cleaning (with Chlor*Rid) and zone overcoat painting of connections with the Termarust high ratio calcium sulfonate coating system.
Detailed comments on observations during the November 23, 2007 site visit are provided below.
The bridge, which was built in the 1970’s, was found to have a severe problem with crevice corrosion and pack rust in almost all of the connections of the lower chord steel box members; as well as between layers of steel plates of the large gusset plate assemblies above the piers.
The project involved: · Removal and replacement of some small secondary steel members, by the General Contractor · Pressure wash cleaning (with Chlor*Rid in the water) of the lower steel box members and selected other members and application of the Termarust high ratio co-polymerized coating system, by a painting subcontractor.
It is important to note: 1. The contract specified use of the Termarust coating system – to stop further development of the crevice corrosion and pack rust; which has:
2. The bridge was painted within the past 10 years, and as may be seen from the photos below, that coating did not stop development of crevice corrosion and pack rust.
3. Regarding inspection and rating of the bridge – the rating for the pack rust is clearly PONTIS Condition State 3; i.e. significant bending of structural members but there are no broken fasteners (rivets).
A copy of page 12 of the project specifications, that shows that Termarust (only) was specified, is shown at the back of this report.
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 NOVEMBER 23, 2007 SITE VISITOn this date the North end of the bridge was visited to look at the condition of the Termarust coating and whether the severe crevice corrosion had been stopped. [This was the only area of the superstructure that was accessible without traffic control.]
Photos No. 17 through 22 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. It may be seen that the color of the Termarust coating, over connections, closely matched the color of the existing (tightly adhered) 3-coat zinc-based coating and it has not faded in color,
3. Along many of the connections (in the lower chord members, where there was serious crevice corrosion and pack rust) there are some areas of dark stain.
These areas are believed to be where the water (from pressure washing) was not completely removed during the air pressure ‘blow-down’ of the connections – with the result that the Termarust TR2200 Penetrant and the TR2100 Topcoats (which have a polar attraction to steel) pushed the ‘rusty water’ out of the connections and onto the surface of the connection – and then they ‘wetted’ the steel and chemically stopped further corrosion.
The fact that these areas have a ‘dark’ color indicates that the active corrosion in the connections has been stopped and there is no longer ‘leakage’ from the connection, and the ‘iron’ in the water has oxidized into a dark color; i.e. it is not bright red.
It should be noted that in many cases, where this has occurred on other bridges, such dark stains can actually be washed off of the Termarust TR2100 Topcoat; i.e. the stains are just laying on the surface.
4. Photos 21 and 22 show a small amount of ‘old’ rust on the edges (corners) of some of the steel plates. Here it is important to highlight the fact that since Termarust TR2100 has a polar attraction to steel – such areas will not lead to undercutting and delamination of the coating (as would occur with most film-forming multi-coat paint systems).
It should be noted that this is a field service example that confirms the results of many tests by several independent laboratories – that show that Termarust does not undercut and delaminate, even after up to 5,000 hours of accelerated testing in environmental chambers.
It is believed that these small areas were probably caused during removal of the scaffolding and containment equipment – and not by Termarust pulling back from ‘sharp’ edges and corners; which it will not do.
REFERENCES Pennsylvania Turnpike Commission Contact Person: Gary Graham, Chief Bridge Engineer – Phone: 717-939-9551
Painting Subcontractor Titan Industrial Painting, Baltimore, MD – Phone: 410-477-1857 Contact Person: Pete Forakis
CLEANING AND APPLICATION PROCEDURES The following Termarust standard procedures were specified and 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
3. Apply Termarust TR2200 Penetrant into all ‘open’ connections; where there is crevice corrosion and pack rust.
4. Apply a caulk (or stripe) coat of Termarust TR2100 Topcoat onto open connections; where there is crevice corrosion and pack rust – minimum 10 mils dry film thickness (DFT).
5. Spot prime areas of bare steel and tightly adhered (contaminant free) rust with 5 mils DFT of Termarust TR2100 Topcoat
6. Overcoat the entire area with another 5 mils DFT of TR2100 Topcoat.
It is important to note that steps 3 through 6 are usually 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 – Crevice corrosion has severely bent the top, the sides and the bottom of the box members. and overstressed the rivets. Note the center ‘edge’ is the connection angle, shown below
Photo 2 – Inside box members, showing angles that connect webs and flanges Note crevice corrosion under the top flanges and the bottom inside connection
Photo 3 – Crevice corrosion and pack rust have severely bent plates and over-stressed the rivets.
Photo 4 – Crevice corrosion and pack rust between the webs and top flange and the connection angle.
Photo 5 – Pack rust has severely bent the top flange and overstressed the rivets
Photo 6 – Close-up of the pack rust between the top flange and the connection angle.
Photo 7 – Typical crevice corrosion and pack rust between the bottom connection angle(s) and the bottom flange of the boxes (Cloth below the member is tarp for cleaning and painting)
Photo 8 – Close-up of typical crevice corrosion and pack rust on bottom of box members.
Photo 9 – A main (built-up) Gusset plate – with crevice corrosion between all of the plates – see below
Photo 10 – Crevice corrosion and pack rust between all levels of gusset plates. Several of the rivets are over- stressed.
Photo 11 – Crevice corrosion and pack rust on most bridge members.
Photo 12 – Crevice corrosion and pack rust on most bridge box members
Photo 13 – Liberally applying Termarust TR2200 Penetrant to all open connections
Photo 14 – Termarust TR2200 Penetrant applied to areas of crevice corrosion and pack rust.
Photo 15 – Termarust TR2200 Penetrant applied to areas of crevice corrosion and pack rust.
Photo 16 – Caulk Coat and Overcoat of TR2100 Topcoat has been applied. Total thickness of TR2100 over open connections is 20 mils Dry Film Thickness (DFT)
Photo 17 – 19 Months after zone painting - note color of old paint was matched.
Photo 18 – 19 months after zone painting of connections (See Note No. 3, above)
Photo 19 – 19 months after zone painting of connections (See Note No. 3, above)
Photo 20 – 19 months after zone painting of connections (See Note No. 3, above)
Photo 21 – 19 months after zone painting – Dark areas are where ‘rusty water’ (from pressure washing that was not blown out) was pushed out of the connection after painting – before the Termarust stopped the crevice corrosion (See comments above)
Photo 22 – 19 months after zone painting – crevice corrosion has been stopped
Figure 1 – Page of Contract Painting Specification Pennsylvania Turnpike Commission Project 05-012-RCTQ-C Rehabilitation of Superstructure on Bridge NB-610, MP 88.79, Carbon County |
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