Cryogenic Breakaway Device(Breakaway Coupling)The solution
The cryogenic liquid loading and unloading system is mainly connected with the hose of the liquid source station, trailer or ship, refueling arm, valve and pipeline system, and its connector adopts DN25-DN100, connecting to fueling nozzle or dry joint or flange type. A breakaway device (breakaway coupling) is required on the refueling pipeline. When the connector is not separated but the other end of the vehicle or boat or external mobile device separated, strong external force will cause the damage to the hose or equipment. When the leakage of cryogenic liquid occurs, the cryogenic breakaway coupling can protect the safety of equipment and personnel in time and turn off emergently.
The structure principle and application of the cryogenic breakaway device are introduced as below
Operating temperature: -196℃ ~ +75℃ (Max. Temperature 300℃)
Sealing rate after separation: 95%-100% sealing rate is set according to different media (pipeline pressure relief)
Application Media: Liquid Oxygen, Liquid Nitrogen, Liquid Argon, Liquefied Natural Gas, Ethylene, Liquid Chlorine, and other low temperature, room temperature media of gas and liquid
4.材质：壳体采用耐低温的 304或 316L不锈钢材料
Material: the shell is made of 304 or 316L stainless steel
装配前进行深冷处理;密封材料采用耐超低温特氟龙材料，密封面经特殊工艺加工达到密封要求。Cryogenic treatment before assembly; The sealing material is made of cryogenic Teflon material, and the sealing surface is processed by special technology to meet the sealing requirements.
5.壳体密封性：零泄漏;Shell sealing: no leakage;
1) In case of emergency, the loading and unloading equipment can be quickly separated;
2) There will be no "break away" happened during routine operation;
3) The two parts separated can effectively achieve the design sealing.
Flow rate: the pipeline with breakaway valve does not affect the original flow rate of loading and unloading, flow rate designed reaches the ball valve's flow rate level; Unlimited flow, no interception.
PICTURE 1 shows the structure of the emergency breakaway device, which is mainly composed of two valve bodies. The main body of the unilateral valve body adopts spring force closing structure, its closing force comes from the disc spring itself.
图 1紧急拉断装置PICTURE 1 Emergency breakaway device
1.主体结构The main structure
阀盖密封Valve bonnet seal
The breakaway device consists of two parts of the valve bodys, the middle is the breakaway bolt, and the two sides are composed of an independent single valve body.It is mainly composed of shell, valve disc, main sealing ring, guide plate, breakaway bolt and circlip.
Breakaway bolt of shell connects left and right valve bodys, and the middle is the circulation hole, circulation area designed meets the requirements of circulation rate. The guide plate is used as the support of the spring and the valve trim. The connection form of breakaway device adopts flanged or welding type.
Valve disc is thimble structure with limit device which is designed to ensure good sealing, simple operation, easy maintenance, and avoid the spool dislocation to cause no liquid phenomenon.
DURABLA sealing material is used between the left and right valve body, with concave-convex surface waterline design and primary /secondary sealings. This sealing material has good elongation at high and low temperature, not brittle, no crack,and have long lifetime.
The sealing degree of valve body after being breakaway by external force can be set. Different sealing rates are designed according to different media. Normally, The sealing rate of LNG, LN2 and LAr is recommended to be 97%. (Users can also consider the sealing rate.Full sealing and pressure relief requirements can be achieved by removing and installing the valve core gasket.) Because the low temperature liquid media in the room temperature atmosphere is easy to be expanded rapidly and urgently, resulting in a sharp pressure increase in hose, but the valve body is designed to not fully sealed, allowing partial pressure relief to protect the hose from bursting because of too high pressure. The sealing degree of flammable explosive media like Liquid oxygen must set as 100%. The venting hole has been set on the valve body for the size >=DN65.
Breakaway Actuator: Breakaway actuator should ensure that the equipment can be automatically and quickly broken away when emergency pulling happened. Also, the actuator must ensure that there is a buffering period before separated, and avoid the occurrence of breakaway during routine operation which may affect normal loading and unloading operations. Corresponding breakway device can be customized according to required pulling force of loading and unloading refueling arm.
Hose-type breakaway actuator
It is mainly composed of double head breaking bolt or single head breaking bolt and nut.
Because metal hose has good flexibility, when the trailer is over the position, it gradually tenses and extends within a certain range. This process reminds of the operator that if you do not take measures to stop, there will be an emergency pull break. The advantage of the hose lies in its own buffering process.
PICTURE 2 shows a schematic diagram of emergency breakaway device installed on the hose processing pipeline. This set of loading and unloading equipment is mainly composed of hose (metal hose), connector, emergency breakaway device and globe valve etc..
4.9.紧急拉断装置Emergency breakaway device
图 2现场布局示意图PICTURE 2 Schematic diagram of site layout
1. Breakaway Process
During normal loading and unloading process, the flexible hose is in a relaxed and free state. When the trailer or ship is driven away and its interface is not separated from the station equipment, the flexible hose tenses and gradually extends and elongates beyond the limit range, the breakaway bolt breaks, and the valve bodies at both ends are separated. After separation, half valve body is left in the line and the other half in the hose, which is sealed by internal spring force.
Note: after emergency breakaway, the valves on station line must be closed quickly to discharge the pipeline pressure. Do not use external force to squeeze the valve disc before pipeline discharged to empty, otherwise it will cause mass leakage of media and serious accident.
Recovery after breakaway
Check whether the middle seal between the left and right valve body is damaged before the emergency breakaway device is restored. If there is damage, remove the main seal seat and replace the main seal of the valve body or the valve disc sealing. Otherwise, replace the breakaway bolt. During the recovery operation, lock the valve bodies at both ends with universal bolts, let them standing for 5-10 minutes, and then replace thebreakaway bolts and tighten the nuts with the torque of 4-5Nm and then complete the recovery work.
Notes and troubleshooting for initial liquid injection
Be sure do the precooling, when the body is slightly frosted, observe if there is a slight leakage among body connection. If there is any leakage, shut down the liquid inlet valve and discharge the pressure. Use 2 pcs of10 mm wrenches gradually lock each snap bolt, do not use large adjustable wrench with no grip to tighten, it will cause the bolt fracture.
There is no direction to install the breakaway coupling. Both ends of the arrow direction can be connected in different directions