Boiler Tube Coating by HVOF – The popular and effective protection method

Among the current leading boiler tube coating measures, the HVOF initiative is the one that should not be ignored. So what is HVOF coating and why is this method so popular and widely applied? Together we will discover the answer in the article below.

What is HVOF boiler tube coating? What are its general features and advantages?

In the opening, we will briefly introduce the HVOF boiler tube coating measure: What is it and what are its specific features? Moving to the next point, there will be several HVOF coating materials listed. To close the topic, we will inform you of some outstanding benefits that the HVOF method brings.

Introduction of Boiler Tube Coating by HVOF method: Definition and working principle

HVOF coating, standing for High-Velocity Oxygen Fuel Coating, is a thermal spray process in which oxygen and fuel are mixed together and fed into the combustion chamber for gas-generating ignition. This gas carries extremely high temperature and pressure and is ejected through the nozzle at supersonic speed.

Powder continues to be injected into this hot gas stream at high speed and is pushed to the surface to be coated. The result is a coating with low porosity and high bond strength to the base material, which in turn provides corrosion resistance.

Most notably, during HVOF injection, the high velocity of the particles generates kinetic energy. One of the biggest benefits of the HVOF boiler tube coating process is that it produces extremely thick and hard coatings without the other extreme heat.

7 key features that make the HVOF boiler tube coating method widely used in the industry

Before learning about HVOF, let’s take a look at the definition of boiler tube coating. This is a single-component water-based technique that is sprayed in application temperatures up to 2000 F (1100 C). Being one of the most effective boiler tube coating methods available today, the HVOF technique can create a coating with the following notable properties:

• Minimal porosity: Approximately 1-2 vol% and low oxide content in the range of 1- 2 wt%.
• Weld-like bond strength: Usually exceeds 80MPa
• Creat high interparticle cohesion
• Enhance the hardness and toughness of the surface (HV 1000+)
• Higher coating thickness than other thermal spraying measures
• Increase corrosion protection
• Minimize hot gas infusion
• Create smoother surface finishes compared to other thermal spraying techniques.

5 main materials being used in the HVOF boiler tube coating process

In order to produce the correct coating and prolong the life of the equipment, the HVOF boiler tube coating method uses a variety of materials during the spraying process. Some of the most common materials include:

• Stainless Steel: When spraying the material with HVOF Stainless Steel, we can create a coating with high density and good bonding without spending too much. These coatings are capable of providing protection against corrosion, cavitation, and grain erosion at low temperatures in the field of rescue and repair.
• Chromium Carbide: Chromium Carbide HVOF coating has micro-hardness and high bonding strength. These coatings are the optimal choice for the anti-corrosion needs of solid particles at high temperatures.
• Tungsten Carbide: HVOF Tungsten Carbide coatings are extraordinarily dense, highly bonded, and well applied to a high thickness. HVOF Tungsten Carbide materials are recommended for highly corroded applications.
• Tungsten Carbide-Cobalt-Chrome: HVOF Tungsten Carbide-Cobalt-Chrome boiler tube coatings are more anti-corrosion in most applications than Tungsten Carbide coatings and are more corrosion protection, thanks to the Chromium content. HVOF Tungsten Carbide-Cobalt-Chrome is ideal for abrasive or sliding corroded applications. HVOF Tungsten Carbide-Cobalt-Chrome coatings are a perfect alternative to hard chromium plating.
• Tungsten Carbide-Nickel Superalloy: Spraying the material with HVOF Tungsten Carbide-Nickel Superalloy produces a well-bonded coating with high corrosion resistance to abrasive particles, hard and frayed surfaces. These coatings are the appropriate solution for hydraulic rods, ball valves, drilling, and saltwater applications.

HVOF boiler tube coating process: Outstanding benefits and Applications

HVOF coatings can be used in a wide range of engineering and manufacturing applications to enhance the surface performance of parts. HVOF is mainly used in corrosion protection, such as subsea pump internals, impeller wear rings, valve plugs and seats (WC-Co, WC-CoCr, WC-NiCr coatings), slurry pump internals, extruder dies and tips, valve balls… This also allows for the cost-effective preparation of high-performance parts made from low-cost or lightweight materials. If processed correctly, the HVOF method causes low environmental impact and produces huge performance gains. HVOF coating is among the top priorities to enhance components by:

• Improving electrical properties
• Lowering and highering temperatures resistance
• Protecting against corrosive chemicals
• Improving the efficiency and lifespan of components

Besides boiler tube coating, the HVOF technique is also used in industries such as oil and gas, electricity, water, mining, petrochemical, chemical, aerospace, papermaking… HVOF coating can be used as an alternative to hard Chrome which is harmful to the environment.

Hopefully, the above article has helped you gain more useful information about the HVOF coating method. Despite possessing many outstanding advantages, this method can only maximize its effectiveness when implemented by a reputable and quality team. Therefore, investors and constructors need to find a unit that provides service and consulting solutions and professional construction, and VIVABLAST is such a unit. We provide a variety of insulation materials with advanced construction techniques and modern equipment. VIVABLAST also has a team of well-trained and experienced technicians who carefully evaluate the customer’s system to provide the optimal boiler tube coating solution. For more information, please contact us via:

• Phone: (+ 84-28) 38 965 006/7/8
• Fax: (+ 84-28) 38 965 004
• Email: vivablast@vivablast.com