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April 5, 2009

Comments Off on Thermal Spray Coatings

Thermal Spray Coatings

A Primary Mission of the Council is to promote effective means of surface preparation in the maintenance industry using water and water/abrasive blasting techniques.

Metallizing is a type of thermal spray coating (TSC) that produces a durable metal coating.

The TSC metal typically applied to steel structures such as highway bridges is either pure zinc or a zinc/aluminum alloy.

A feed wire of the TSC metal is heated to a molten state by flame or electric arc and propelled by air spray onto a surface.

Likely reasons for this have included a relatively high initial cost and a lack of familiarity and experience with metallizing among bridge painting contractors.

To date, TSC coatings have been applied to approximately 150 (out of 200,000) steel bridges in the United States, totaling just over 2 million square feet.

Recent improvements in application equipment have doubled productivity rates to the point where initial costs are more competitive.

Many factors must be considered when determining the economic impact of a technology on a bridge maintenance painting project.

A cost model was developed for this FHWA study which estimates itemized project costs and evaluates economic impacts.

The technology observation reported was for metallizing using recyclable steel grit for surface preparation.

Since both recyclable steel grit and metallizing are different form our assumed state-of-practice, we will compare the site visit to a recyclable steel grit removal project with airless spray applied coatings.

Blasting with recyclable steel grit followed by application of a three-coat paint system with a stripe coat.

3. Blasting with recyclable steel grit followed by application of 85/15 Zn/Al metallizing with a full sealer coat.

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April 5, 2009

Comments Off on ElectroStrip(TM) Technology

ElectroStrip(TM) Technology

A Primary Mission of the Council is to promote effective means of surface preparation in the maintenance industry using water and water/abrasive blasting techniques.

An electrolyte is contained in a liquid-absorbent material to which a counter electrode is attached.

This apparatus, often combined with a liner, is attached to the painted metal surface (typically steel) with magnets.

A DC voltage of 8 to 10 volts is applied for ½ to 2 hours.

ElectroStrip(TM) Corporation (Export, PA) was contracted to remove the existing coating system from one interior beam on the west abutment span of structure 2067 utilizing their ElectroStrip(TM) technology.

Connections made while under electrical load will arc with high-intensity light flash and high temperature, capable of causing injury.

Faulty ground may also result in personal injury if a worker provides an alternate path to ground.

A maximum productivity rate of 10 ft2/man-hr was observed during the demonstration.

The last two days showed a drop in productivity because the contractor did not assist with the process.

Air monitoring during the Hand/Power tool cleaning of the remainder of the structure showed the air borne Lead dust levels were well over the OSHA PEL for Lead.

‘Once-through’ abrasive blasting will typically have two blasters, one helper, and one foreman having an equivalent productivity rate of 50 ft2/man-hr.

‘While structure was grounded to complete the circuit’ perhaps the following would be clearer: ‘While the connection to the inherently grounded structure completed the circuit’ Faulty ground as occupational hazard: voltages not exceeding 18 V (max. voltage of our rectifier) are generally considered to present no shock hazard.

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April 5, 2009

Comments Off on Blasting and Waste Disposal

Blasting and Waste Disposal

A Primary Mission of the Council is to promote effective means of surface preparation in the maintenance industry using water and water/abrasive blasting techniques.

Costs for hazardous waste disposal are more than double that of non-hazardous waste disposal costs.1 This, combined with the liability involved with hazardous waste disposal has brought other options to the forefront in the bridge painting industry.

Two relatively new solutions to the hazardous waste problem in bridge painting are the use of admixture blended abrasives and liquid applied pretreatments.

The liquid pretreatment is a liquid material that is sprayed on the painted surface at a specified thickness, allowed to dry, then blasted off with the underlying lead-based paint.

The manufacturer of the admixture guaranteed their product by refunding the cost of the admixture if the waste produced tests hazardous for lead.

When using these products, there are additional costs involved, including the price of materials and additional labor needed to use them.

pretreatment As can be seen from the previous example, both the admixture and liquid pretreatment can reduce maintenance painting costs.

The other factor, availability, refers to the location of the jobsite to a distribution center for the materials.

Liquid pretreatment can be purchased and shipped rather easily, similar to paint.

Both the admixture blended abrasive and liquid pretreatment cost more than expendable abrasive, however, those increases are less than the disposal cost savings realized.

2. The use of admixture blended abrasives did not seem to affect the contractors productivity with the Torbo® Wet Abrasive Blasting System.

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April 5, 2009

Comments Off on Abrasive Injected Water Blasting

Abrasive Injected Water Blasting

A Primary Mission of the Advisory Council is to promote effective means of surface preparation in the maintenance industry using water and water/abrasive blasting techniques.

The Abrasive Injected Water Blasting (AIWB) process involves introducing an abrasive into a high pressure water stream where it is delivered to the surface to be blasted.

AIWB will impart a profile on the substrate and is capable of cleaning to an SSPC-SP-5, though flash rusting may occur.

This equipment is useful in spot repair requirements for highway structures where localized corrosion and/or damaged paint areas require repair.

While performing the spot repair requirements, AIWB is also capable of feathering transition areas of intact paint, which surround areas prepared to bare metal.

In addition, the surrounding areas of intact paint are sweep-blast to remove delaminated coating.

The observed structures were part of a multiple bridge maintenance painting contract for Virginia Department of Transportation’s Northern Virginia District.

Due to the nature of this repair work, (i.e. spot prepare corroded areas, and overcoat), production rates during a given shift were dependant upon the amount of old coating that was removed.

The water consumed per square foot was also dependent on the amount of coating deterioration on the structure, shown in Table 1.2.

During this eight hour demonstration shift the contractor utilized two Carolina Equipment & Supply Aqua Miser D-44 AIWB units with one blaster per unit to remove all coatings down to bare metal.

This cost model calculated cost for maintenance painting of structures with varying extents of coating deterioration for a comparison between abrasive injected water blasting and hand/power tool cleaning surface preparation methods.

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April 5, 2009

Comments Off on Water/Abrasive Systems in Cleaning and Profiling

Water/Abrasive Systems in Cleaning and Profiling

Slurry blasting and surfaces.

This slurry material is forced through the blast hose to the nozzle using compressed air, similar to the method used to move dry abrasive through hoses in conventional abrasive blasting operations.

However, the Torbo® system allows the blast operator to control the following directly at the nozzle: abrasive mixture quantity, air pressure and nozzle on/off.

The use of this slurry media reduces airborne dust, which could possibly reduce the containment requirements compared to dry abrasive blasting.

The depth of the profile is dependent on the size and type of abrasive used as well as the air pressure.

A wide variety of abrasives may be used such as sand, plastic, glass, slag, bicarbonates and other manmade abrasives.

The contractor performing the work was PbX and consisted of a crew of five men: one foreman, two blasters, and two helpers.

This was done using the Torbo® Wet Abrasive Blasting System, which allowed the blasters to turn off the abrasive and use only low-pressure fresh water.

The abrasive admixture is a proprietary additive used to render lead in waste nonleachable.

For the I-40 bridge painting project, abrasive consumption was reduced from an assumed average of 10 lb/ft2 for once-through dry abrasive blasting to 3 lb/ft2, a 70% decrease.

VII: The Use of Admixture Blended Abrasives and Liquid Applied Pretreatments in the Removal of Lead-Based Paint, Corrpro Companies, Inc.

To compare the two surface preparation technologies, a cost model built for this FHWA study was used.

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April 3, 2009

8 Comments

MegaRust 2009

Mega Rust Workshop

Date : 2009-03-12
2 Separate Workshops on “How to Inspect for Flash Rust”
To replace the description sent out on 2009-03-09
Contact Person: Lydia Frenzel

Frenzel tried to cover two workshops with one write-up. This was confusing to some people.

The tag line “Practical Solutions for Practical Problems” reflects Dr. Frenzel’s approach to life with the “Keep it Simple Stupid” approach. If you are an inspector and never been on a waterjetting job, OR If you have ever been in an argument concerning light, moderate, or heavy flash rust, this workshop is for you.

Here are two separate Press Releases.
=================================
Who: Lydia Frenzel
Date: June 8, 2009
Where: Megarust, Norfolk, VA
For Registration : www.nstcenter.com

Description: Surface Preparation using WaterJet or Wet Abrasive Blast Cleaning. \How to Inspect for Flash Rust.
You will learn how to Inspect for FLASH RUST
WHAT happens to the SURFACE?

This four hour interactive workshop will feature “HOW TO INSPECT FLASH RUST” –new training material, funded by National Shipbuilding Research Program, that augments the FROSIO, NACE and SSPC Coating Inspector Courses.

How the acceptance of Waterjet Cleaning has changed the industry’s view on what is Surface Preparation over the past 30 years.

This workshop includes, but is not limited to:
What is “flash rust?”
How do you reduce the amount of Flash Rust during the project?
Field Examples of 4 methods to determine the amount of flash rust
Wiping with cloth held in hand
Wiping with swatch of cloth
Wiping with Brush
Tape Pull Test
What does the surface look like after pressure washing?

What are the field studies of 20 years showing on the performance of coatings over surfaces cleaned with hand-held and robotic waterjet systems?

Certificate of Attendance and dvd will be issued

Level of Competence- All levels- certified inspectors, engineers, contractors, specifiers, jetters
Sponsored by: Advisory Council and MegaRust
Spend personal time with Dr. Lydia Frenzel, “Waterwitch of the West”, and the chair of the SSPC/NACE waterjetting and water-abrasive committees, and author of SSPC C-13 WJ course.

=======================
Who: Dr. Lydia Frenzel, and other industry Experts
Date: Tuesday August 18,2009
Where: WJTA Conference, Houston Texas
For Registration: www.wjta.org for details
Cost: $280- $340 for Tuesday workshop only;
You can register for the workshop without registering for the entire WJTA conference.

Description: “Waterjet Technology, Basics and Beyond,”- Full day Course

“Waterjet Technology, Basics and Beyond” –
The morning sessions cover the waterjet technology basics: history (30 minutes), equipment (40 minutes), applications (50 minutes) and safety (50 minutes)
Afternoon: 2 hour break out sessions covering: Cleaning Applications, Cutting Applications, Hydro-Excavation and Surface Preparation Applications, followed by Panel Q&A

The Surface Preparation session will feature “HOW TO INSPECT FLASH RUST” –new training material, funded by National Shipbuilding Research Program, that augments the FROSIO, NACE and SSPC Coating Inspector Courses.

This workshop includes, but is not limited to:
What is “flash rust?”
How do you reduce the amount of Flash Rust during the project?
Field Examples of 4 methods to determine the amount of flash rust
Wiping with cloth held in hand
Wiping with swatch of cloth
Wiping with Brush
Tape Pull Test
What does the surface look like after pressure washing?

Time permitting: How the acceptance of Waterjet Cleaning has changed the industry’s view on what is Surface Preparation over the past 30 years.

Certificate of Attendance and dvd will be issued

Level of Competence- All levels- certified inspectors, engineers, contractors, specifiers, jetters
Sponsored by: Advisory Council and WJTA

Spend personal time with Dr. Lydia Frenzel, “Waterwitch of the West”, and the chair of the SSPC/NACE waterjetting and water-abrasive committees, and author of SSPC C-13 WJ course.
========

Lydia M. Frenzel
PO Box 2139
San Marcos TX 78667
Tel/Fax (1) 800-308-7416

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