Thermal Protective Spray Coating Combats Corrosion in Large-Volume Water Pumps

Metalized Hydraflo
Rusty Steel

Combat inevitable corrosion by metalizing

Corrosion is an enemy of large-volume water pumps but metalizing / coating metal technique is a great solution. A chemical reaction between the component surface and the reacting fluid passing through the pump causes corrosion, which can result in permanent damage to non-stainless materials and affect the performance as well as the efficiency and life expectancy of pumping equipment.

One solution might be to use corrosive resistance steel such as ASTM242 “Corten Steel” with different types of epoxy coating. MWI uses ASTM242 “Corten” steel as their standard in most of their pumps. For standard drainage application, this combination is sufficient in combating corrosion however, in more corrosive environments, these pumps will require constant monitoring and recoating which may present a problem with maintenance. In these cases, the next best solution might be to upgrade to a grade of stainless steel to manufacture the pumps. For saltwater, brackish water, and other corrosive applications, stainless steel pumps might be the only solution and its long-term benefits outweigh the initial material cost. MWI all stainless-steel pumps supplied to salt industry have shown to be in operation for 35 years or more before needing replacement. Clearly in these cases, the initial investment in material has clear long-term benefit.

Metalized Hydraflo Trinidad

Metalizing / thermal protective spray - an alternative to stainless steel

For other applications, the increase in material cost might be an overkill. For those customers seeking an alternative to an all stainless-steel pump, metalizing has become a viable and cost-effective solution that we can offer.

Metalizing is a process of adhering a different metal powder/granular coating to another type of metal using electricity. This coating provides an extra layer of protection against oxidation and is just one of the techniques MWI can provide to customers when manufacturing quality pumps. MWI can also manufacture large volume pumps from a variety of stainless steels and duplex materials when required, although in some cases, metalizing may be a most cost-effective solution.

Metalizing is the generic name for a thermal spray coating process used to protect equipment against corrosion. MWI Pumps recently went through the process of sandblasting, handling, masking, and metalizing (with pure zinc) some pumps in an application in Trinidad; an area with a highly corrosive-prone hot, humid, and salty climate.

Benefits of thermal protective metal spraying

There are many benefits of using this metalizing process to protect large water pumps from corrosion:

  • Durability: This process actually bonds the metal to provide a service life of decades longer than paint.
  • Eco-friendly: This process contains no volatile organic compounds and uses only compressed air with electricity.
  • Fast application: Metalized coatings cool in seconds unlike paint which takes days to cure.
  • Cost: With a service life of well more than 50 years, metalizing significantly reduces the need to continually sandblast and paint.

Six ways metalized coating out-performs paint

Sometimes painting is used to protect equipment from corrosion, however, using a thermal protective spray coating process can provide substantial benefits.

For projects that call for metalizing, clear communication between the project managers, general managers, fabricators, project engineers, and metalizing field supervisors is required. This communication will assure that the project is successful and achieves the most durable long-term corrosion protection system available.

Here are six ways metalizing is a better choice than paint:

  1. Life Cycle Cost Savings: Metalizing has been proven to last up to 40 times longer than paint and other coatings, which equates to significant cost-savings in maintenance, labor, and materials.
  2. Adhesion Strength: Metalized coating and paint both form a mechanical bond with a blast steel surface. However, typical adhesion strength for metalized coatings is much stronger than prime paints. Unlike paint, the adhesion strength does not degrade when exposed to thermal cycling.
  3. Dry Film Properties: A metalized coating is harder and stronger than paint. Combined with the bond properties, this makes a metalized coating more resistant to impact, abrasion, and wear than paint. A metalized coating is not affected by UV exposure.
  4. Anodic Protection: A zinc or aluminum metalized coating anodically protects the underlying steel by sacrificial mechanisms. Protection is more effective and more efficient than zinc paint because the metalized coating is in direct contact with the steel without “interference” from the paint binder.
  5. Chemical Resistance: Metalized coatings (particularly aluminum) achieve some measure of resistance due to the formation of a tightly adherent oxide layer. A topcoat may be applied to improve protection or provide desired appearance.
  6. Faster and Longer Lasting: Metalizing offers the benefit of no cure time, no mixing, no hazardous waste, and no shelf life limitations.