Low-temperature welding and silver brazing Be sure to remember what the recommended valve is for and analyze the environment in which it is used, to determine what valve is best suited for installation. Before installing the correct valve, read the installation guide to prevent damage to the valve and to ensure that the valve is fully functional. 1. Cut the pipe along the vertical direction and trim to remove burrs and measure the pipe diameter. 2. Use a gauze or wire brush to clear the pipe and the cutting area to make the metal surface shine brightly. It is recommended not to use steel wool. 3. Apply flux to the outside of the pipe and to the inside of the weld cap. The flux must completely cover the weld surface. Use solder sparingly. 4. Make sure the valve is open. First pipe heating. As much heat is transferred from the pipe to the valve. Avoid prolonging the heating of the valve itself. 4a. Silver Brazing Method: Assemble the parts that need to be brazed. If the solder-coated parts are allowed to stand upright, the moisture in the solder evaporates and the dry solder easily peels off, exposing the exposed metal surfaces to oxidation. When connecting and assembling, insert the pipe into the pipe sleeve until it encounters blockage. Assembly is to ensure a solid support, so that the entire brazing operation can be maintained in a straight line position. Note: For valves of 1 inch or larger nominal diameter, it may be difficult to heat the connecting parts to the desired temperature at once. In order to maintain a normal temperature over a large area, two torches are usually required. It is advisable to preheat the entire jacket area appropriately. It is recommended to heat the connecting parts with acetylene flame. First, heat the pipe 1 inch above the valve and then flame the pipe alternately up and down around the pipe a short distance and rotate the pipe at an appropriate angle to avoid burning through the pipe. Flame to continuous movement, not allowed to stay at a certain point. In the valve sleeve base flame baking. Heating should be uniform, with a flame on the valve and pipe flame baking process should be extended to the valve on the flux no longer make a sound. Do not overheat the valve. As flux becomes liquid and semitransparent on the pipe and valve, the flame begins to advance and retreat along the axis of the connecting member to maintain the heat of the connecting member, particularly the valve sleeve base. 5. Use the right amount of solder: If using a wire solder, 3/4 inch solder is used for 3/4 inch nominal valves, and so on. If too much solder is used, some solder may flow through the pipe block and block the seal area. During the installation of the connecting parts, it can be seen that the solder and brazing alloy continue to flow. 5a. Silver Brazing Method: Place the wire or rod on the pipe socket in the valve. When the welding rod or wire into the junction to be removed from the flame above. When the alloy flows into the junction, move the flame back and forth. Once the proper temperature is reached, the alloy will quickly and easily flow into the space between the pipe housing and the valve sleeve. After the connection is full, you will see the edge of the solder alloy. 6. When the solder is in a sticky state, use a brush to remove excess solder. After the solder has cooled down, place a fillet around the port of the valve. Silver brazing If different brazing materials are used, the strength of the brazed joint is not very good, and the strength depends on the normal, wide range of cleaning and maintenance work between the pipe shell and the valve sleeve. The mechanical tolerances and surface smoothness of the internal diameter of silver-brazed valve bushings are very precise to ensure adequate adhesion. Note: Care should be taken to observe the residues of cleaning media during cleaning and removal. Brazing on surfaces that have been soiled or incorrectly cleaned is less than satisfactory because the silver brazing alloy does not flow or adhere to the oxide and the oily surfaces and exposed, Easily oxidized and lead to voids and debris repel solder. Threaded connections Dirt, dirt or any foreign material build-up in the pipe may interfere with the efficiency of the valve and severely damage the valve's critical components. The interior of the pipe must be thoroughly cleaned with air or steam. When tapping the pipe, measure the size and length of the pipe threads and avoid clogging the pipe with the seat and disc. Thoroughly clean the thread end to remove any harmful steel or iron deposits. If you want to weld more solid, it is necessary to use Teflon tape or pipe adhesive. Only a small amount of pipe adhesive is used on the pipe threads, but pipe adhesives must not be used on the valve threads. Do not allow any pipe adhesive to flow into the valve body to avoid damage to the disc and seat. Before installation, cut off the fluid through the valve to make the valve work properly. Completely close the valve before installation. Place the wrench over the hexagonal head of the pipe to avoid any possible deformation. After installing the valve, to support the pipeline: the drooping pipe will cause the valve deformation and failure. Flange connection In order to ensure the correct installation of the valve flange, you need to follow the following steps. Carefully clean the joints first and then loosely attach two or three bolts to the base. Next, carefully insert the gasket into the connection. Bottom bolts help to position the washer and hold it in place. And then insert the bolt to be used to cross-tighten the way, do not use around tightening, which helps to eliminate the over-concentration of pressure). After normal use for a period of time, check that all bolts are tightened and re-tightened as necessary.
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