Connection methods for CPVC pipes and FRP/PVC pipes

It can be heat-welded. Welding rods can also be used. FRP/PVC is a composite pipe: after the PVC pipe inside is welded, FRP is added on the outside for protection.

Use of glue in CPVC/UPVC pipe connections 1. Glue: 1.1. Glue is generally composed of polymer resins and solvents in a certain ratio. When used for bonding pipes, the solvent in the glue softens and penetrates the outer diameter of the pipe’s socket and the inner diameter of the fitting’s spigot, allowing the pipe/fitting to bond more tightly together when subjected to bonding forces ； The polymer resin in the glue fills the gaps between the pipe fittings, and after curing, it bonds the pipes/fittings together as one unit. 2. Cleaners: 2.1. Cleaners are used before gluing to clean, soften, and penetrate the outer diameter of pipe sockets and the inner diameter of fitting sockets. Cleaners are not necessary for pipe connections under 3\", but are required for connections larger than 3\" prior to applying glue. 3. Socket: 3.1. The inner diameter of the socket for pipe fittings bonded with glue is generally designed to be tapered, meaning its outer diameter is slightly larger than its bottom diameter. The purpose of the taper design is to ensure that the inner surface of the socket and the outer surface of the spigot can bond together after being softened and subjected to pressure, thereby achieving the desired bonding strength. 3.2. Before applying the adhesive, the socket and spigot of the pipe should be tried out first; the depth to which the fitting’s spigot is inserted should be approximately 1/4 to 3/4 of the total depth of the spigot. (Sometimes it may be possible to insert the pipe/fitting all the way in, but if the fit is too tight, bonding can be achieved by increasing the amount of adhesive used or the number of application times, as well as by extending the curing time appropriately.) ； However, if the pipe/fitting remains loose even after being fully inserted, such a fitting cannot be used. ) 4. Key points for bonding: 4.1. Before bonding, the connection surfaces of the pipes and fittings should be wiped clean with a dry cloth to ensure they are free of dust, sand, water marks, oil, and other contaminants ； When the oil adhering to the bonding interface is difficult to remove, it can be polished off with fine sandpaper. 4.2. The adhesive layer must be in sufficient quantity to fill the gaps in the bonding surfaces of the spigot and socket. A coating of sufficient thickness allows the glue to remain wet for an extended period, keeping the surface moist during pipe connection. When applying the glue, apply it first to the inner diameter of the socket and then to the outer diameter of the spigot; use a moderate amount of glue on the socket to prevent excess glue from squeezing into the inner wall of the pipe at the top of the socket during bonding, which could contaminate the pipe or valve body. 4.3. After applying the adhesive, the bonding surfaces of the pipes must be fully dissolved and softened. Note that the glue must be in a semi-liquid state, with a moist and softened glue layer, when bonding pipes, so that the two surfaces to be bonded can quickly form a single sol layer; otherwise, \"dry bonding\" may occur. 4.4. During bonding, the socket of the pipe must be inserted to the bottom of the spigot of the fitting, rotated 1/4 to 3/8 turn, and pressure must be applied for 1 to 3 minutes until initial curing occurs to prevent slippage. 4.5. After bonding, any excess glue that overflows from the joint should be wiped away promptly with a cloth (it is necessary to check whether a ring of glue has formed; if there are interruptions or bubbles in this ring of glue, it indicates that insufficient amount of glue was used, and the bonded component must be discarded and the process repeated). 4.6. After bonding, the pipeline must be allowed sufficient curing time to maximize the adhesive strength between the components through the evaporation of solvents and chemical reactions in the glue. 5. Precautions: 5.1. Pipe bonding should not be carried out in environments with high humidity; the work area must be kept away from sources of fire, impacts should be avoided, and direct sunlight should be prevented. Operations should not be conducted at temperatures ≤ -5°C. 5.2. Due to the different requirements regarding operating temperature and pressure for CPVC and UPVC pipes, corresponding adhesives and cleaners should be used. 5.3. For applying glue, use a bristle brush or nylon brush; the brush width should be 1/3 to 1/2 of the pipe diameter (for bonding small pipes, the ball brush in the glue container can be used directly). Store the glue in an open-container with a lid, opening it as needed. 5.4. Glue may separate due to storage or other reasons (precipitation occurs as a result of the different densities of the components). It can be mixed evenly using a metal rod or similar tool before use (the mixing brush inside the glue container is not long enough to reach the bottom of the container, so its mixing effect is poor). 5.5. For large-diameter pipes (6″ and above), a tractor must be used to assist with bonding during installation; it is strictly prohibited to use tools to strike the pipe during the fitting process. 5.6. Construction at low temperatures < 4.5 ℃ **Be sure to dry out any moisture, ice, or snow water ； The pipe can be placed in the sun for several hours first ； The curing time of the adhesive joints must be extended, and during the bonding process it is necessary to prevent the joints of the fittings in the upstream pipeline from being subjected to twisting, impacts, and other stresses. 5.7. When the temperature is above 38°C, care should be taken to place the pipe ends, fittings, and welding agents in a cool place as much as possible before bonding, or to carry out the bonding operation in the morning or evening ； Wiping the pipe surface with a damp cloth soaked in water can lower the pipe temperature (but make sure the moisture on the pipe surface is dried before applying glue) ； After applying the glue, connect the pipe (socket) to the fitting (spigot) as soon as possible.