Low Temperature Ball Valve

Applicability

Low temperature ball valves are mainly used in the chemical equipment of ethylene and LNG etc. to handle low temperature liquid medium like ethylene, liquid oxygen, liquid hydrogen and so on. These types of inflammable and explosive medium can be volumetrically expanded by several hundred times when being gasified under temperature rise, and are difficult to manufacture due to their highly penetrative and leaky properties.

Structural Properties

1. The materials of compression parts can endure the expansion and shrinkage resulted from the temperature variation of medium, and seal structure is away from permanent deformation under temperature changes. To work under the conditions below -100℃, the parts of valve shall be subject to deep cooling treatment before precision machining. Namely, have the parts cooled in liquid nitrogen box, when the temperature of parts reaches -196℃, keep the temperature for 1~2h, then take them out to have them to the normal temperature naturally, and do in this way twice.

2. Bonnet is extended for the purpose to protect the function of packing box, making packing box somewhat away from low temperature to ensure good seal of packing. Besides, it can be wound with cold insulating materials to prevent loss of cold energy. The length of neck depends on service temperature and the thickness of cold insulating material. When the effect of packing seal turns lower, fill in grease to form up oil seal layer from the middle of packing box. see combined packing the reliability of seal.

3. To serve a temperature below -100℃, the material of valve stem shall be treated with chromeplating or nitriding to enhance the surface hardness of valve stem and the sealing reliability of packing.

4. Low temperature ball valve takes a structure to avoid abnormal pressure rise. As the medium in low temperature valve is gasified and rapidly expanded in volume, the pressure will goes extremely high. When the pressure in the middle cavity of valve rises, the middle cavity and the inlet side can be communicated, or a relief can be mounted at the inlet side of valve, thus to ensure the safe use of valves.

5. The gaskets used on low temperature ball valves may function reliable seal and restoration under normal and low temperature or under the conditions of temperature changes.

Main Material

Low temperature ball valve Technical Specifications

Design and Manufacture: API 6D, ASME B16.34 (BS5351), API 608, MSS-SP-72

Face to Face Dimension: ASME B16.10, API 6D

Flange Connection Dimension: ASME B16.5

BW Connection Dimension: ASME B16.25

Test and Inspection: API 598, API 6D

Fire-Safe Design: API 607/6FA

Main Dimensions

class 150

class 300