Wedge gate valve
Model: Z41H-16C Z41H-25C Z41H-40C
Introduction to rising stem gate valve:
Wedge type rising stem gate valve belongs to the block valve type. Because the valve disc is a gate plate, it is generally called a gate valve. When the gate valve is closed, the valve stem moves downward, depending on the height of the sealing surface of the gate valve and the sealing surface of the valve seat, they are smooth, flat and consistent, and stick together to prevent the flow of media, and rely on the top wedge to increase the sealing effect. The types of gate valves can be divided into wedge type and parallel type, and each type can be divided into single gate and double gate. Z41H-16C wedge gate valve is widely used in waterworks, petroleum, chemical, pharmaceutical, electric power, fire protection, environmental protection water treatment and other industries. It is used to open and close the pipelines of steam, water and oil media with nominal pressure ≤ 1.6Mpa.
Executive standard of gate valve:
Design specification: GB/T 12234
Structure length: GB/T 12221
Connecting flange: JB/T 79
Test and inspection: JB/T 9092
Pressure temperature: GB/T 9131
Product identification: GB/T 12220
Z41H-16C Wedge Gate Valve It is used to cut off or connect the medium flow in the pipeline. The gate valve cannot be used as a regulating valve. It must be in the fully open or fully closed position. The product has the advantages of saving effort in opening and closing, low flow resistance, etc. When the rising stem wedge gate valve is closed, its closing part moves along the vertical direction of the center line. The downward movement of the valve stem depends on the smoothness and consistency of the sealing surface of the gate valve and the sealing surface of the valve seat, which adhere to each other to prevent the flow of media, and relies on the top wedge to increase the sealing effect.
Gate valve Maintenance quality standards and specifications:
1. Valve body: the valve body shall be free of sand holes, cracks, scouring and other defects, and shall be timely treated after discovery. There shall be no sundries in the valve body and pipeline, and the inlet and outlet shall be unblocked. The screw plug at the bottom of the valve body shall ensure reliable sealing without leakage.
2. Valve rod: the bending degree of valve rod shall not be greater than 1/1000 of the total length, or it shall be straightened or replaced. The ladder shaped thread of valve rod shall be intact, free of defects such as broken thread and undercut. The wear amount shall not be greater than 1/3 of the thickness of ladder shaped thread. The surface shall be smooth and clean, free of rust and dirt. The contact part with packing seal shall be free of sheet corrosion and surface delamination, Those with uniform corrosion spot depth ≥ 0.25mm shall be renewed. The finish shall be above ▽ 6, the connecting thread shall be intact, the pin shall be fixed reliably, the cutting rod and the cutting rod nut shall rotate flexibly after combination, there shall be no jam in the whole stroke, and the thread shall be coated with lead powder for lubrication and protection.
3. Packing seal: the pressure and temperature of the packing used shall meet the requirements of the valve medium. The product shall be attached with a certificate of conformity or be subject to necessary test and identification. The packing specification shall meet the size requirements of the seal box. It is not allowed to use oversized or undersized packing instead. The height of the packing shall meet the requirements of the valve size, and a thermal tightness allowance shall be reserved. The packing interface shall be cut into an oblique shape with an angle of 45 °, The joints of each ring should be staggered by 90 ° - 180 °. The length of the cut packing should be appropriate. There should be no gap or overlap at the joint placed in the packing box. The packing seat ring and packing gland should be intact and free of rust. The packing box should be clean and smooth. The gap between the gate rod and the seat ring should be 0.1 - 0.3 mm, and the maximum should not exceed 0.5 mm. The packing gland The clearance between the periphery of the seat ring and the inner wall of the stuffing box is 0.2-0.3mm, and the maximum clearance shall not exceed 0.5mm. After the hinge bolts are tightened, the pressing plate shall be flat and straight, and the tightening force shall be uniform. The clearance between the inner hole of the packing gland and the pressing plate and that around the valve rod shall be consistent. The packing gland shall be pressed into the packing chamber for 1/3 of its height.
4. Sealing surface: The valve disc and valve seat sealing surface after maintenance shall be free of spots and grooves, the contact part shall account for more than 2/3 of the valve disc opening width, and the surface finish shall reach more than ▽ 10. Assemble the test valve disc, and ensure that the valve core is 5-7 mm higher than the valve seat after the valve disc is inserted into the valve seat to ensure tight closing. When assembling the left and right valve discs, ensure flexible self adjustment, and the anti stripping device shall be intact and reliable. 3.5 The screw threads of valve rod nuts and internal bushings shall be intact without broken threads or disorderly threads. They shall be reliably fixed to the housing without looseness. All bearing parts shall be intact and rotate flexibly. The inner and outer sleeve and the steel ball surface shall be free of cracks, rust, heavy skin and other defects, and the disk spring shall be free of cracks and deformation, otherwise it shall be replaced. 3.5.4 The fixing screw on the surface of the locking nut shall not be loosened. The valve stem nut can rotate flexibly, and the axial clearance is guaranteed to be no more than 0.35mm.
