Ceramic valve elements
Currently we muster a series production of ceramic valve elements that will feature thermal strength and withstand thermal shocks, wear caused by hydro and abrasive impacts as well as effects of aggressive environments. Ceramic elements are further incorporated into control and stop valve units manufacture by Russian companies.
Advantages of ceramic elements
Advantages of ball valves with locking ceramic elements inside of a metal shell compared to steel valves of various configuration include:
- higher wear resistance when used in pipelines transporting abrasive and aggressive substances as they are insensitive to aggressive environments while showing enhanced hardness;
- up to 50000 lock/unlock cycles without failure;
- a wide range of operating temperatures (from -200 to 800°С)
-reliable operation under higher pressure in a pipeline (up to 40 MPa);
-less efforts required for lock/unlock operation due to elimination of a “clutch” effect between valve elements (as provided by ceramics properties and special structure of the ball valve).
Chocks with beans made of ceramics instead of hard-alloys do not show wear under abrasive impact of sand slurries, as they feature hardness of 9 on Mohs scale compared to quartz value of 7. Chemically non-reactive ceramics (except of fluorohydrogen acid) do not interact with alkalis and acids thus significantly increasing a service life of valves operating under severe conditions and in some cases ceramics may be the only possible solution.
Materials for ceramic ball valves and chock beams are chosen based on their resistance to effects of aggressive operating environment and physical/chemical properties.
Property | Sintered silicone carbide | Zirconium dioxide | Alumina 99,5% |
---|---|---|---|
Density, g/сm3, not less | 3,10 | 6,02 | 3,9 |
Micro-hardness, GPа, within | 23 – 33 | 12- 14 | 17 - 22 |
Bending strength, МPа | 350 - 450 | 800 – 850 | 300 – 350 |
Young's modulus, GPа, within | 390- 420 | 180- 220 | 350 – 380 |
Crack resistance, МPа*m1/2, within | 3 – 4 | 8 – 10 | 3.5 - 4 |
Compressive strength, МPа, not less | 2500 | 3000 | 3000 |
Thermal conductivity, Wt/m*К | 80 – 130 | 2 – 3 | 15,5 - 16,7 |
Coefficient of thermal expansion, 106 К-1, within | 2,8 – 4 | 10 – 11 | 8 – 9 |
Comparison Characteristics of Steel Stop Valves and Stop Valves with Ceramic Gate Units
Application | Characteristics | |
---|---|---|
Steel valve | Ceramic valve | |
Oil transportation pipes | Pipeline pressure up to 16 MPa | Pipeline pressure up to 40 MPa |
Oil and gas equipment elements | 350 operating cycles before failure | 2000 operating cycles before failure |
Chemical industry | Operating temperature from -40 to + 200 °С. | Operating temperature from -200 to + 810 °С. |
Pulp and paper | Durability (up to 2000 lock/unlock cycles) | Durability (up to 50000 lock/unlock cycles) |