TOPCOR is rapidly becoming one of the nation's leaders in Thermal Spray Metalizing for structural and industrial process systems.

Briefly stated, Thermal Spray Metalizing is a process of applying a molten metal onto a substrate, typically carbon steel or concrete, for corrosion control and/or cathodic protection purposes. This process is often referred to as:

  • THERMAL SPRAY
  • METALIZING
  • METALLIZING
  • TSA (THERMAL SPRAY ALUMINUM)
  • METALIZED ZINC CATHODIC PROTECTION
What is extremely important to understand is that thermal spray coatings provide not only a barrier coating, but also cathodic protection to a steel substrate. With traditional paint systems, a small scratch or area of mechanical damage can quickly lead to total failure of the system due to migration of moisture and corrosives. With thermal spray coatings such damaged areas are fully protected by the cathodic protection capabilities of the coating itself, preventing damage from migrating any further than the small area of damage. Additionally, that small area will only see a flash rust, but no further corrosion will continue.

There are many applications for the thermal spray technology, but TOPCOR specializes in four specific areas:
  1. BARRIER COATING AND CATHODIC PROTECTION FOR PROCESS EQUIPMENT UNDER INSULATION TO PREVENT CUI (CORROSION UNDER INSULATION)
  2. BARRIER COATING AND CATHODIC PROTECTION FOR STEEL STRUCTURAL COMPONENTS
  3. CHEMICAL RESISTANT BARRIER COATING FOR INTERNAL LINING OF VESSELS
  4. CATHODIC PROTECTION OF REINFORCING STEEL IN STRUCTURAL CONCRETE
Barrier Coating and Cathodic Protection for CUI Protection

NACE (National Association of Corrosion Engineers) has identified Thermal Spray (and TSA in particular) as the lowest life-cycle cost corrosion barrier system, far outperforming traditional paint systems. SSPC (Society for Steel Protective Coatings) has also identified thermal spray coatings in it's Interim Standard C.1.2.B, stating the following:

"Thermal spray coatings (TSCs) are used extensively for the corrosion protection of steel and iron in a wide range of environments. The corrosion tests carried out by the American Welding Society and the 34 and 44 year marine-atmosphere performance reports of the LaQue Center for Corrosion Technology confirm the effectiveness of flame [and wire-arc] sprayed aluminum and zinc coatings over long periods of time in a wide range of hostile environments. The British Standards Institution code of practice for the corrosion protection of steel specified that only TSCs give protection greater than 20 years to first maintenance for the 19 industrial and marine environments considered and that only sealed, sprayed aluminum or zinc gives such protection in sea water immersion or splash zones."

TOPCOR has written its own specification for this process, which we term TSCCP (Thermal Spray Coatings and Cathodic Protection) (note to web designers…please put link to the PDF here).

CUI has been identified as the most significant maintenance cost item in industrial facilities throughout the world and Thermal Spray Aluminum has been identified by the largest industrial corporations as the best solution to the problem (to name a few of the pioneers, ExxonMobil, Shell, Dow Chemical).

TOPCOR has significant experience applying TSA and TSCCP to process systems under insulation, including piping, heat exchangers, process columns, reactors, storage tanks, etc.

Barrier Coating and Cathodic Protection for Steel Structural Components

Galvanizing is a mature industry and well known for providing excellent corrosion resistance for structural components. Thermal Spray Metalizing can be thought of as an in-situ galvanizing, in which case we would apply either zinc or aluminum.

Applications are unlimited. One recent example is the structural steel and crane rail for a crane system inside of a paper machine room in a paper mill. Due to the constant high humidity (with corrosive vapors) no paint system was able to hold up for even one year. During a very short outage, we blasted the columns, beam and rail and applied thermal spray aluminum to the entire system. This is expected to provide a maintenance free corrosion barrier.

In the oil and gas industry, many offshore structural components are being protected with thermal spray coatings. Riser and conductor pipes are commonly being protected by thermal spray coatings where rubber linings and other systems are proving unsatisfactory. Other offshore components such as buoyancy cans and structural steel are also being coating with thermal spray aluminum or other metals.

Chemical Resistant Barrier Coating for Internal Lining of Vessels

For very difficult internal corrosion issues, thermal spray coatings are being used in lieu of paints or high alloy vessel materials. Applications such as digesters and storage tanks in paper mills and high temperature power plant component internals are being lined with specialty metals such as Inconnel and other nickel derivatives.

Cathodic Protection of Reinforcing Steel in Structural Concrete

Cathodic protection of steel components is a long-accepted and well understood technology. But the cathodic protection of reinforcing steel inside of structural concrete is relatively new, but a growing method of providing significant life extension to chloride contaminated concrete structures.

The most active market for this process has been coastal bridges, piers, docks, condominiums, etc. Over years, as the chlorides from the salt atmosphere penetrate the concrete cover and eventually reach the steel, advanced corrosion of the reinforcing begins, resulting eventually in the spalling of the concrete the subsequent loss of structural integrity.

Traditional concrete repair techniques will temporarily restore the structural integrity, but the chlorides that remain in the structure will continue to corrode the reinforcing steel and in some cases the corrosion could become more active after a repair due to intensifying the corrosion process on the unrepaired areas.

Cathodic Protection of Reinforcing Steel is a process that accepts that corrosion will continue to occur but provides a sacrificial (or in severe cases impressed current) anode to corrode preferentially to the reinforcing steel. With this system in place, the reinforcing steel in 100% protected from corrosion as long as the anode is in place.

TOPCOR uses the Metalized Zinc Cathodic Protection system primarily. This is the process of thermally spraying zinc onto the surface of the concrete, connecting this zinc anode to the reinforcing steel through a negative connection and using the normal moisture inside of the concrete to complete the electrical circuit and provide a "cell" that "conducts" the corrosion process to the zinc, allowing the zinc to corrode instead of the reinforcing steel. In this electrical circuit, the reinforcing steel becomes the cathode and the zinc material becomes the anode.

We have many references with state DOTs, Counties, the Department of the Navy, The Bureau of Indian Affairs, The Department of Energy, etc., where this process has been used to extend the life of concrete structures.

Process and Equipment

TOPCOR uses two thermal spray process:
  1. Twin Wire Arc
  2. Flame Spray
Twin Wire Arc is our primary process and is the most efficient. The process basically takes two wires of the metal to be sprayed and melts them at the tip of a gun, which is connected to pneumatic air to propel the molten wire particles onto the substrate. The equipment is very mobile and virtually any structure in any setting can be protected. Many of our projects are over water and we can set up this equipment on relatively small barges.

Flame spray is similar to the welding process in that it uses oxygen and acetylene to create a flame and a single wire passes through this flame, where it is melted and, again with pneumatic air, propelled against the substrate. This process is generally slower and used only where the twin wire arc process is not suitable.

TOPCOR manufactures its own twin wire arc equipment, called TOPARC TS, and provide equipment and consulting to non-competing shops and contractors throughout the world market.

Please visit our equipment site for more information.