High-pressure swivel joint structure analysis

 In the process of cementing and hydraulic fracturing, the high-pressure swivel joint is one of the main components connecting cement trucks and wellheads. With this high-pressure swivel joint, the lines can be joined to each other at any angle, while the high-pressure swivel joint can absorb most of the vibrations due to uneven pumping.

     The high-pressure swivel joint has special requirements for its components such as bearings and seal rings. The elasticity and strength of the high pressure swivel joint short tube and the elbow must be considered together. In order to increase the life and reliability of the high-pressure swivel joint, the bearing seal must be improved.

     Figure 1 is a high-pressure swivel joint of a new orange structure. In order to make the sealing ring more tightly attached to the sealing surface, the position of the oblique opening of the packing is shifted by 90° compared to the ordinary high-pressure swivel joint. This causes the oblique opening to face the direction of the flow. When the elongation is 1 meter, the oblique opening becomes softer, so that the packing can be sealed under a small pressure (20-50 kg/cm 2 ).
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Figure 1 high pressure swivel joint
1-wire bent pipe; 2-bend pipe; 3-packing; 4- diameter 10 mm ball; 5-sealing ring; 6-bushing; 7-conical seat; 8; short tube; Vertebral body 10 - sealing ring; 11 - outer casing nut; 12 - plug cover; 13 - grease mouth; 14 - bolt; 15 - spring pad.

     These measures reduce the likelihood that abrasive debris will fall into the gap between the packing and the contact surface.

     It was observed during the use of the high-pressure swivel joint that the outer diameter of the seal ring was the fastest at the part of the part P (Fig. 1). The packing starts to move toward the gap B when the pressure is high and is quickly stabbed in the portion of the part P.
     To prevent sprinting, the packing is assembled with a metal ring 1 (Fig. 2). The ring is stamped from a 0.5 mm thick steel plate and placed in a mill to be formed by pouring rubber.

high pressure swivel joint sealing packing.jpg

Figure 2 Metal ring of high-pressure swivel joint packing
1-ring; 2-rubber
     In order to reduce the entry of dirt from the end face (direction of the V arrow) into the bearing, a rubber seal ring is placed in front of the bearing to protect the dirt from entering the bearing until the bearing wears. When 6 gaps are formed between the ball and the bearing groove (Fig. 3), if the vibration is large, the dirt enters the Δ gap between the connecting parts and penetrates into the bearing, as indicated by the K arrow (Fig. 3).
 Therefore, it is impossible to completely prevent dirt from entering the bearing. In order to remove the dirt from the bearing after work and to maintain normal lubrication of the bearing, there is a hole in the plug cover 12 and the grease fitting 13 is provided. The fresh lubricating oil is injected into the bearing through the grease fitting through the grease fitting to discharge the dirt. In this way, the lubrication of the bearing can be restored after each work to increase the service life of the high-pressure swivel joint.

Figure 3 high pressure swivel joint sealing packing

Metal ring of high-pressure swivel joint packing.jpg