Powder coating metallic surfaces for corrosion protection and aesthetic purposes has grown by leaps and bound in the United States and more so in other parts of the world. The use of powder coating on aluminum and steel sheet products has led the way to greater technology and reduced costs as the demand has grown. …
When all coats of a paint system are applied to bridge steel in an enclosed shop, the quality of the cleaning and painting is typically quite good. The steel is blast cleaned and painted in a controlled environment, minimizing or eliminating the concerns with temperature, relative humidity, dew point, and inclement weather that often plague …
Total Shop Painting of New Bridge Steel – Pros and Cons Read More »
Steel beams used for bridge and highway structures are frequently curved to accommodate the design of a structure. This can be accomplished by cambering or sweeping. Cambering is the curving of a beam about the strong axis of the member, while, sweep applies to the curving of a member about the weaker axis. Cambering is …
Cambering: Cold Versus Heat for Steel Bridge Beams Read More »
Introduction The installation of thermal spray coatings (TSC) or metalized coatings is becoming more common for protection of new and existing structural steel members on locks & dams, bridges, tanks and other industrial structures. While the installation of thermal spray coatings is typically more labor intensive and more costly than traditional liquid-applied coatings systems, the …
Surface Preparation of Steel Prior to Application of Thermal Spray Coatings Read More »
There are several methods by which a coating can protect steel from corrosion. One of the most effective methods is by providing galvanic protection. Galvanic protection works by covering the steel surface with a metal that will preferentially corrode instead of the steel when the surface comes in contact with an electrolyte, usually water. All …
Hot Dip Galvanizing Versus Zinc Rich Primers – Which Protects Better? Read More »
The following is a guideline for witnessing and verifying qualification testing of Welding Procedure Specifications (WPS) according to the AASHTO/AWS D1.5-2015 Bridge Welding Code. The guidelines identify what the third-party inspector is required to do when witnessing a test, what the inspector can do to facilitate the process for the fabricator and the reviewer, and …
Guidelines for Witnessing Welding Procedure Qualification Testing Read More »
When steel is shop-painted, it is usually primed with a zinc coating, and the remaining coat(s)applied to all surfaces except the top of top flanges that will be embedded in concrete. If shear studs will be installed in the top flanges after painting, it is often questioned whether the paint must be removed prior to …
Introduction Surface profile is defined as a measurement of the maximum peak-to-valley depth generated by abrasive blast cleaning and impact-type power tools. These operations effectively increase the surface area and provide an “anchor” for the applied coating system. The surface profile depth must be compatible with the total coating system thickness; typically, the thicker the …
Surface Profile Measurement Options on Rough/Pitted Steel Surfaces Read More »
This Month’s Case Was Selected From Several Investigations Related To Failures That Occur When Applying Coating To The Underside Of Metal Deck Panels (Fig. 1). This Case Focuses On An Adhesion Failure Of Coatings Applied To Previously Painted Deck Panels. A paint contracting company was hired to apply an epoxy ester dry-fall coating to portions …
Galvanizing presents many challenges to painting operations. While the zinc coating can add substantial life to steel surfaces, its surface chemistry and electrochemical activity can result in conditions leading to adhesion failures of applied organic coatings. The key to successful painting lies in recognizing the many surface conditions presented by new and weathered galvanizing and …