ZFV provided butterfly valve be used in low temperature, which is cryogenic butterfly valve.
Generally the cryogenic butterfly valve use extended shaft/gland design . the length of the extension will be sufficient to maintain the stem packing at a temperature high enough to permit operation within the normal temperature range of the packing material. The general packing material is graphite, the normal temperature of packing should be 8 degree C and higher. There are different stardards mention different requirement length of extention, cover using temperature range from -46 degree to -196 degree C even lower temperature .
To assure the low temperature raw material meet requirement relative standard, normally need to apply impact testing to raw material. the normal way is V sharp impact testing.
It needs to apply cryogenic treatment to main valve part, before precision machine work, in case useing temperature lower than certain temperature such as -120 degree C, or customer have special requirement. Advantage to apply cryogenic treatment
1. Improve the hardness and strength of the workpiece
2. to ensure the dimensional accuracy of the workpiece
3. improve the wear resistance of the workpiece
4. improve the impact toughness of the workpiece
5. Improve the stress distribution inside the workpiece and improve the fatigue strength
6. improve the corrosion resistance of the workpiece
Zhejiang Zhengfeng valve provide cryogenic butterfly valve by standard API, EN, ISO, GB stardards
Zhejiang zhengfeng valve .