Extended stem low temperature ball valve

Extended stem low temperature ball valve introduction
Extended stem low temperature ball valve is suitable for medium temperature -40℃ ~ -196℃, cryogenic ball valve is called low temperature ball valve,which is mainly used for ethylene, liquefied natural gas (LNG) plant, gas LPG, LNG storage tanks to accept base and goonhilly, air separation equipment, oil chemical tail gas separation equipment, liquid oxygen, liquid nitrogen, liquid argon, carbon dioxide cryogenic storage tank and tank lorry, psa oxygen generating device, etc.The output of liquid low-temperature media such as ethylene, liquid oxygen, liquid hydrogen, liquefied natural gas, liquefied petroleum products, not only flammable and explosive, but also in the heating to gasification, gasification, the volume expansion of hundreds of times.

Extended stem low temperature ball valve specification
Size: 1/2 ~ 24 "(DN15 to 24"))
Pressure grade: 150~1500LB(PN16~PN250)
Connection: Flanged, welded, threaded.
Cryogenic ball valve materials: LCB, LC3, CF8.
Working temperature: -46℃, -101℃, -196℃.
Applicable medium: liquefied natural gas, ethylene, propylene, etc.
Driving mode: manual,gear, bevel gear, electric,pneumatic.

Extended stem low temperature ball valve Structural design feature
Extended stem low temperature ball valve is divided into low-temperature cryogenic floating ball valve  and low-temperature cryogenic trunnion ball valve. For the temperature is higher than -50℃, the long-neck structure is generally not adopted. For the ball valve with the temperature lower than -50℃, the neck length T is generally 250mm, or determined by the design and calculation of our company.Low temperature ball valve is mainly used to output liquid low temperature medium such as ethylene, liquid oxygen, liquid hydrogen, liquid nitrogen, liquid ammonia, liquid propane, liquefied natural gas, liquefied petroleum products, etc., not only flammable and explosive, and in the heating to gasification, gasification, the volume expansion of hundreds of times.
Material selection
The material of liquefied natural gas valve is very important, the material is not qualified, will cause the outer leakage or inner leakage of the shell and sealing surface;The comprehensive mechanical properties, strength and steel degree of the parts can not meet the use requirements or even fracture.Causes the liquefied natural gas medium to leak causes the explosion.Therefore, in the development, design and development of liquid natural gas valve process, material is the primary key problem.Valve body and bonnet: LCB(-46℃), LC3(-101℃), CF8 (304) (-196℃).
Low temperature treatment
Our factory to the production of low-temperature valves through special low-temperature treatment, the rough machining parts in the cooling medium for several hours (2-6 hours), to release the stress, to ensure the low-temperature performance of materials, to ensure the precision machining size, in case of the valve in low-temperature working conditions, caused by temperature deformation caused by leakage.

Extended stem low temperature ball valve main part material

No	Part name	AS to ASTM		SS to ASTM
1	Body	Type A352 LCB	Type A352 LC3	Type F304(L)	Type F304(L)
2	Bonnet	Type A352 LCB	Type A352 LC3	A182 F304(L)	A182 F304(L)
3	Bolt	A193L7	A193 3 B8	A193 B8	A193 B8M
4	Nut	A193L7	A194 8	A194 8	A194 8M
5	Seal ring/Gasket	RTFE+Cu/Nylon/1010/PPL
6	Ball	A182 F304	A182 F304（L）	A182 F304(L)	A182 F316(L)
7	Shaft	A182 F304	A182 F304（L）	A182 F304(L)	A182 F316(L)
8	Packing	RTFE+Cu/Nylon1010/PPL/Graphite
9	Gland	A105N	A351 CF8
10	Lever	A193 L7	A193 B8	A193 B8	A193 B8
11	Suitable temperature	≥-40°C	≥-101°C	≥-196°C

Extended stem low temperature ball valve part design characteristics
1. Low temperature ball valve body:
Extended stem low temperature ball valve is of full size structure. The ball valve has no obstruction at full open position. The internal size conforms to API6D regulations.The valve body can be made into a one-piece structure, two-piece or three-piece structure, etc., to reduce the leakage point.The ball valve has top mounted type and side mounted type structure, which can realize online replacement of internal seals. The ultra-low temperature ball valve with nominal diameter ≥NPS2 is designed as a fixed ball.
2. Low temperature ball valve stem:
Extended stem low temperature ball valve is equipped with extended stem for the purpose of protecting the stuffing box.Ensure that the temperature of the stuffing box is above 0℃, so that the stuffing can work normally.The design of the extended stem is mainly about the length of the neck, which is related to the thermal conductivity, thermal conductivity area, surface heat dissipation coefficient, heat dissipation area and other factors of the material. The calculation is quite complicated, which is generally obtained by the experimental method or by adopting relevant standards.
3. Low temperature ball valve drop plate:
The Extended stem low temperature ball valve and the extended bonnet are provided with a drip tray to prevent condensed water from flowing into the insulation layer.The location of the drop plate also indicates the highest location of the cryogenic ball valve for on-site insulation material.Drill a connecting hole on the valve cover to connect the extended cavity with the ball valve to ensure that abnormal pressure boost will not occur to the extended cavity.
4. Low temperature ball valve self-relief
The relief of the abnormal pressure boost in the middle cavity is realized by the self-relief valve seat. The self-relief direction of the middle cavity is the upstream pipeline.
5. Low temperature ball valve stem seal:
The Extended stem low temperature ball valve stem is sealed with low leakage and low maintenance structure.According to the specific size of the design of two or more channels of sealing, so that the valve stem sealing class to meet iso15848-2 B requirements, but also to prevent water from water pressure test into the flexible graphite packing, durability class to meet ISO15848-1 C01 class.A disc spring is arranged at the bolt connection of the packing press plate to compensate the load and avoid the influence of the active load under the alternating temperature.
6. Low temperature ball valve anti-static device:
Antistatic devices (steel ball and spring) are provided at the stem/ball junction and stem/bonnet contact to prevent static electricity from accumulating on the ball.Under the 12 v dc testing, the spheroid and valve cover and the resistance value between the valve stem and valve cover not more than 10 Ω.Ultra-low temperature fixed ball valves shall also be designed to meet the API6FA or API607 standard safety fire protection structures.
7. Low temperature ball valve Seat seal:
In the ultra-low temperature state, the valve seat and body with the sealing ball valve lip sealing ring, is the most appropriate choice.The precision of lip seal ring itself is high, and the precision and surface finish of matching metal parts are also high.The seat ring material is made of ultra-low temperature PCTFE (KEL-F) which can be used between -196-300℃.
8. Low temperature ball valve mechanism:
Extended stem low temperature ball valve can operate normally when the stem is at an Angle of 30° from the vertical line.Manual ball valves (including actuators and gear drives) shall be equipped with locking devices so that ultra-low temperature ball valves can be locked in full open or full closed positions.The actuator can be replaced and maintained online and can operate under freezing conditions.