PaintSquare.com


The First Word in Protective & Marine Coatings

A Product of Technology Publishing / PaintSquare
JPCL | PaintSquare News | Durability + Design | Paint BidTracker

Problem Solving Forum

| More

April 23 - May 5, 2010

A specification for a bridge to be built of high-performance weathering steel (HPS GR50/GR70W) requires an SSPC-SP 10, a profile of 3 to 5 mils, and metallizing with a final dft of 10-12 mils. What challenges, time, and costs are associated with obtaining the profile, primarily in the shop but also in the field? Are there any long-term performance issues with metallizing over weathering steel?


Selected Answers

From Chuck Pease of MMI Tank on May 5, 2010:
It can be very difficult and costly to achieve a 3-5 mil blast profile on weathering steel because it has an inherent surface hardness greater than conventional carbon steel. It can therefore take 30-40 percent more hours of labor to achieve a 3-5 mil profile.

Weathering steel construction plays a part because a typical weathering steel bridge girder is unique in design to minimize the accumulation of debris and moisture.

We could not achieve a 3-5 mil profile using even using G-25 steel grit with a 40-50 Rockwell C hardness while meeting an SSPC-SP 10 degree of cleanliness. The best we could come up with was 1.75 mils. We were finally able to achieve an average of 4.2 mils using a mixture of G18/G16 steel grit.

We were able to convince the DOT to allow a more aggressive profile as a better anchor profile for the subsequent metallizing.

As for long-term performance issues with metallizing over weathering steel, I am not aware of any to date.

In specifying weathering steel for structures to be metallized, the specifier should take care not to include stitch welds; stiffener connections to bottom flanges should be specified to be continuous welds all along the stiffeners, and snipes should be eliminated or continously welded to the webs.

Other areas of concern for long-term metallizing performance would be to eliminate areas that will hold water or condensation for long periods of time, as crevice corrosion can develop and the oxide coating found on typical weathering steel will not develop on surfaces that are continually wet or covered with debris.

Zinc metallizing systems are porous until the zinc oxidizes, so care should be taken to design weathering or carbon steel structures where these micro-enviroments cannot develop.

Please sign in to submit your answer this question    

Tagged categories: Bridges


Current PSF Question | Submit a PSF Question | Full PSF Archive

Termarust Technologies
Termarust (HR CSA) Chemically Stops
Active Corrosion

Truss bridge treated in 2000 with Termarust's (HR CSA) field-proven rust mitigation system chemically stopped corrosion, crevice corrosion & pack rust.


U.S. Zinc

Offering custom grades and packaging of zinc dust, oxide, metal and fines, U.S. Zinc provides direct shipping to locations worldwide. Helping the world work™


Surface Prep Supply
Surface Prep Supply

Blast It! Coat It! We have you covered every step of the way. Supplier of:
• Abrasives
• Equipment
• Accessories
• Protective Coatings
888-331-7737(PREP)


Midsun Specialty Products
Stopaq Corrosion Protection Services by MSP

Stopaq coatings are impenetrable to water, oxygen and bacteria. Save labor costs with simple surface prep and a 30 year guarantee.
Visit: midsunsp.com/stopaq or Call 888-866-8273


Abrasives Inc.
Check our Prices for Blast Abrasives

Faced with higher abrasive costs? We invite you to call & check our rates on Black Magic® coal slag and other quality blast materials. Abrasives Inc. 800-584-7524


Spider, a Division of SafeWorks, LLC
Complete Suspended Access Solutions

Need access? From platforms & hoists to rigging & fall protection, Spider leads the industry in rentals, sales & service. Call 877-774-3370 or click today.


SAFE Systems, Inc.
Portable Dust Collectors for Tough Environments

Trailer and skid-mounted models in numerous sizes, powered by electric and/or diesel. Sloped roofs, multiple dust inlets, high static, dampered fans. Lockable power & drive compartments.

 
 
 
Technology Publishing

The Technology Publishing Network

The Journal of Protective Coatings & Linings (JPCL) PaintSquare
Durability + Design Paint BidTracker JPCL Europe

 
EXPLORE:      JPCL   |   PaintSquare News   |   Interact   |   Buying Guides   |   Webinars   |   Resources   |   Classifieds
REGISTER AND SUBSCRIBE:      Free PaintSquare Registration   |   Subscribe to JPCL   |   Subscribe to PaintSquare News
MORE:      About PaintSquare.com   |   Privacy policy   |   Terms & conditions   |   Site Map   |   Search   |   Contact Us
 

© Copyright 2000-2014, Technology Publishing / PaintSquare, All rights reserved
2100 Wharton Street, Suite 310, Pittsburgh PA 15203-1951; Tel 1-412-431-8300; Fax 1-412-431-5428; E-mail webmaster@paintsquare.com