Mainly Material of Braid Packing
Graphite packing, Carbon fiber Packing, PTFE packing, Ramie Packing, Cotton Packing, Acrylic packing, Aramid packing,Synthetic Fiber Packing,ect.
Braid Way Introduce
With the continuous emergence of production processes, the preparation forms of fillers have gradually diversified. Depending on the different usage conditions and environments, different preparation forms have a direct impact on the sealing performance and service life. The main weaving forms used for packing materials include square braid;lattice braid;core-crossed braid;inter-locked braid;rolled braid;braided over braided etc. Mainly analyze the situation of the following four weaving methods as below:
1. SQUARE BRAID is a process of weaving using eight spindles running on two tracks, without a core at the four corners and in the middle. The cross-section of the woven product is square, characterized by loose roots, but with a certain compensation effect on shaft vibration and eccentricity. It is only used for small section fillers, but the large cross-sectional size will result in rough patterns on the surface of the fillers, loose structure, and poor density
2. LATTICE-BRAIDED is done using 8, 12, 16, 24, 36, 48, 60 and other spindles on two tracks, and the nesting is determined according to the specifications of the packing. Generally, 1-4 layers are woven without a core in the middle. The packing material in the nesting layer is dense and has strong sealing performance. However, due to being a nesting layer, there is no fiber connection between the layers, which makes it easy to layer. Therefore, it is mostly used for static sealing or low-speed equipment.
3. CORE-CROSSED BRAIDED is made by weaving 8, 12, 16, 24, 36, 48, 60 spindles on three or four tracks. The cross section is square, the surface is flat, the elasticity and wear resistance are good, the strength is high, the density is good, and the contact surface with the shaft is larger and more uniform than the braided type. The fiber gap is small, so the sealing is good. After the surface layer is worn, the entire filling material will not loosen, and the service life is long. It is a relatively advanced weaving structure.
4. INTER LOCKED BRAID is a weaving process that uses rubber or metal as the core, with fibers on the outside, and layers are woven layer by layer according to the needs. Similar to sleeve weaving, sandwich weaving has good density, high strength, good bending performance, and good sealing performance. However, like sleeve structure, the surface layer is easy to fall off after wear. It is generally used for pumps and valves, and is rarely used for reciprocating equipment.
Summary: When choosing a packing, the weaving form of the packing should be selected according to the specific operating conditions of the equipment, in order to enable the packing to perform its intended sealing performance.
How to choose the appropriate packing?
How to choose the appropriate packing? When selecting packing, two things must be considered.
- The working condition requirements should match the performance of the packing. You can choose the most suitable packing according to relevant technical data.
- The correct selection of packing size must be based on sealing requirements. To determine the cross-section,
Please use the following formula to calculate:
Cross section=(packing box diameter - valve stem diameter)/2
Damaged devices may require slightly larger cross-sectional packing to compensate for the damage.
What are the precautions before installing the sealing packing?
Precautions before installing sealing packing:
Removing old packing and inspecting the packing box is a key aspect of the initial installation preparation.
Before filling, use special tools to remove all the old packing and wipe the packing box clean
Observe whether there are defects such as damage and eccentricity in various parts of the packing box. Damaged valve stems, shaft sleeves, and packing boxes can all affect the performance of the packing.
Check if other components are still applicable. Replace all damaged parts.
Import notice for cutting and installing sealing packing
Details to be noted for cutting and installing sealing packing
Select the appropriate packing and use a cutting machine to accurately cut the required length of packing ring. If there is no packing cutting machine, cut according to the packing length L=(shaft diameter d+packing width s) X1.07X. Generally, on the rotating shaft, use a 90 ° straight cut, and on the valve, use a 45 ° cut. Never attempt to wrap the packing box with packing to determine the length. Alternatively, wrap the packing around a pipe that is the same as the valve stem and press it tightly, but do not stretch the packing. Then cut it into a sample ring and check if it can correctly fill the space, ensuring that there are no gaps at its interface. Then, the sample ring can be used as a standard to cut other packing rings. If these finished products are completed on a flat surface and the packing is soft or easily deformed, a small strap can be made based on the sample ring, and the remaining packing ring can be made according to the rope.
When the packing is used for valves, the cross-section of the packing is the same as the space of the valve, and it is best to use a per-loading ring. When used for pumps, the cross-section of the packing and the space of the valve (about 0.3mm-0.6mm) create a leakage gap between the shaft and packing, which is conducive to lubrication and heat dissipation.
. Install one packing ring at a time, ensuring that each packing is not covered with dust or other debris. If necessary, the packing ring should be lubricated with the same clean lubricating oil as used on the valve stem. Install each packing ring in a 90 ° staggered manner. Slowly pull the ring apart in the axial direction.
Conclusion
From above introduce, we can get a comprehensive understanding of gland packing. It can help us to more clearly know how to choose braid packing and how to correctly install braid packing.It’s widely use in various fields,choosing suitable gland packing can reduce wear and extend machine life.
