Habonim Catalog Interactive 2024 V04 15022024 - Catalog - Page 136
HIGH TEMP. VALVES
LTPN Technology
Low Temperature Plasma carboNitriding (LTPN) technology
Austenitic stainless steels (304, 316) have excellent chemical resistance to corrosion and are used
extensively in a variety of environments and industries including oil & gas, marine, medical,
chemical and petrochemical. The use of these steels is limited, however, due to their low wear
resistance, low hardness and sensitivity to galling. Conventional surface treatments, such as
nitriding, are very effective in providing metallic surfaces with high wear resistance. However,
high temperature processes will cause chrome carbide and nitride formation, thereby lowering
the free chromium percentage of the part exposed to the high temperature and decreasing
its corrosion resistance.
Limiting the temperature of the heat treatments to less than 450 ˚C / 842 ˚F forms a supersaturated
layer with excellent wear resistance, while at the same time preserving the corrosion resistant
properties of the stainless steel. Special, parametric processes of plasma nitriding for austenitic
stainless steel have been successfully developed. These processes yield a gradual hardness profile,
to give an optimal stress distribution within the treated depth. A micro-hardness of over 1000HV
(equivalent to 72 HRC) is achieved on the surface of the parts, imparting the steel with a high
degree of scratch and wear resistance.
The ideal solution for severe applications up to 400 °C / 752 °F
Habonim’s unique LTPN surface treatment improves mechanical wear properties of austenitic
stainless steels without affecting their corrosion resistance. LTPN provides austenitic stainless
steel, ball and seats with the additional hardness necessary to operate without galling at elevated
temperatures. For example, at 400 °C / 752 °F the LTPN layer retains its hardness for 15,000 hours of
continuous operation, which typically translates into an in-service life-expectancy of 20 months.
The rate at which the LTPN layer decomposes decreases exponentially with temperature reduction.
Figure 1 shows the life-expectancy for the LTPN layer at different application temperature levels.
Figure 1 - Life-expectancy for the LTPN layer at different application temperature levels
100000000
10000000
1000000
Hours
100000
10000
1000
100
10
1
°C
°F
200
250
300
350
400
450
500
392
482
572
662
752
842
932
Temperature
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HIGH TEMP. VALVES
