Processing technology of steel lined PTFE pipe fittings

The processing technology of steel lined PTFE pipe fittings mainly includes the following methods:
1、 PTFE Sodium Naphthalene Solution Treatment Adhesive Method
Preparation of processing solution: Add a certain amount of sodium to a solution of tetrahydrofuran and naphthalene, with the mass fraction of sodium controlled at 3%~5%. Stir at room temperature for about 2 hours until the solution turns dark brown or black in color.
Workpiece processing: Soak the PTFE workpiece to be processed in the processing solution for about 510 minutes, then remove it and soak it again in the solution for 35 minutes.
Adhesive treatment: Choose epoxy resin, silicone or polyurethane as the adhesive, evenly apply it to the treated surface to be bonded, and immediately perform bonding. After bonding, place it at 24-30 ℃ for 24 hours to ensure a firm bond.
This method introduces polar groups on the surface of PTFE through chemical reactions, improving its adhesion performance and enabling PTFE to firmly adhere to the inner wall of steel pipes.
2、 Loose lining tube process
Material preparation: Cut the PTFE rods produced by molding into fine strips using a lathe, which will serve as the lining material for the liner tube.
Wrapping and sintering: PTFE fine strips are manually or mechanically wrapped around a pre designed mold to achieve the required thickness. Then, 3-4 layers of alkali free glass tape are wrapped around the outside and secured with iron wire. Then it is sent to the sintering furnace for molding treatment.
Cooling and demolding: After sintering, remove the mold and cool it with water. After cooling, use manual or mechanical methods to demold and obtain a loose lining tube.
Assembly and flanging: Insert the loose lining tube into the steel pipe and perform flanging treatment to ensure a tight fit with the steel pipe.
This method is suitable for atmospheric and positive pressure pipelines, but not for pipelines with negative pressure.
3、 Inner wrapped steel wire tight lining tube process
Film wrapping: First, wrap several layers of polytetrafluoroethylene film on the mold.
Wire winding: Spiral wrap a steel wire (diameter 0.5-1mm) around a polytetrafluoroethylene film.
Wrap the film again: Wrap several layers of polytetrafluoroethylene film around the steel wire.
Sintering molding: Place the wrapped workpiece into the furnace for sintering molding.
Filling resin: Insert the sintered workpiece into the steel pipe and fill the gap between the outer wall of the PTFE lined pipe and the inner wall of the steel pipe with filling resin (to remove residual air).
Curing treatment: After the resin is filled and cured, a spiral corrugated structure is formed that meshes with the outer wall of the lining.
The inner wall of the steel lined PTFE pipe fittings produced by this process is smooth, and the outer wall forms spiral ripples due to the volume of the steel wire and its external elasticity. This structure not only improves the negative pressure resistance of the pipe fittings, but also effectively limits and compensates for the expansion and contraction of the PTFE lining.
4、 Other processing techniques
In addition to the three main processing techniques mentioned above, there are also other methods such as PTFE push (extrusion) pressing tube tight lining straight tube technology, which are also used in the production of steel lined PTFE pipe fittings. These methods have their own characteristics and are suitable for different usage environments and media conditions.
In short, there are various processing techniques for steel lined PTFE pipe fittings, and the appropriate method should be selected according to the specific usage environment and medium conditions. Meanwhile, strict control of process parameters and quality standards should be implemented during the production process to ensure the performance and quality of the product.