Habonim Catalog Interactive 2024 V04 15022024 - Catalog - Page 138
HIGH TEMP. VALVES
Coatings
Surface coating applies an outer layer of new material on the body. The following types of surface
coating methods are available in the Habonim metal seated series: chromium carbide with nickel
chrome binder (Cr3C2), tungsten carbide with cobalt binder (WC-Co), and stellite welding.
Cr3C2 (Chromium Carbide)
Chromium carbide with a nickel chrome binder is applied by a High Velocity Oxygen Fuel
(HVOF) creating a 0.3mm hard outer layer. The Cr3C2 coating that is applied to high strength
steels, results in a micro-hardness of up to 68HRC. This coating resists cryogenic temperatures
down to -196 ˚C / -320 ˚F and high temperatures up to 815 ˚C / 1500 ˚F. This multipurpose
wear resistance coating is used extensively in power generation, refining and hot catalyst
handling services. Its corrosive limitations are in wet sulfur or chloride environments, where
sulfuric acid can form and attack the coating.
WC-Co (Tungsten Carbide)
Tungsten Carbide with a cobalt binder coating is applied by HVOF techniques similar to Cr3C2.
The WC-Co coating is applied mainly to 400 series martensitic stainless steel to provide microhardness that reaches 72HRC. This coating resists cryogenic temperatures down to -196 ˚C /
-320 ˚F and high temperatures up to 538 ˚C / 1000 ˚F. WC-Co is a coating that consists of a hard
metal alloy based on a Tungsten Carbide + Cobalt composition.
Stellite
A cobalt-based stellite coating provides excellent mechanical wear resistance, with good
corrosion resistance at temperatures up to 538 ˚C / 1000 ˚F. The stellite is applied by a Plasma
Thermal Arc (PTA) method. Most stellite alloys are cobalt based with elements of chromium (Cr),
carbon (C), tungsten (W) and nickel (Ni). Stellite 6 is broadly used in the pulp and paper industry,
as well as in refining applications, such as catalyst handling and hydrocracker processes.
Surface Treatments/
Coatings
Process
Method
Process
Material
Coating
Thickness
Min. Hardness
Max Temp*
Corrosion
Resistance
LTPN
Plasma carboNitriding
Nitrogen, Carbon
25-80 µm
72HRC
See fig.1
Excellent
CR3C2
HVOF spray
Chromium, Carbon Nickel
0.3 mm
68HRC
815 °C / 1500 ˚F
Good
DN WC-Co 40
HVOF spray
Tungsten, Carbon Cobalt
0.3 mm
72HRC
538 °C / 1000 ˚F
Excellent
*All temperatures above 650 °C/1200 °F refer to the coating performance only and not to the valve design
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HIGH TEMP. VALVES
