During the construction of plastic pipelines, plastic flanges are often used to connect with cast iron flanges, iron valves and other pipe fittings. There are two main types of flanges in our factory: one is the injection flange below Φ315 (there are two types of socket and bonding), the other is the socket flange of various specifications through welding and fiberglass composite, butt joint First of all, you should consider whether the standards implemented by these two flanges and the connecting flanges are consistent, and whether the pressure levels are the same. The standards currently implemented basically adopt national standards, and users sometimes also use flanges of the Ministry of Metallurgy or other standards. Village power levels are generally 1.0MPa, 1.25MPa, 1.6MPa, etc. Only when flanges with the same standards and pressure levels are used for docking, the outer circle, hole spacing and other dimensions can be matched.
Our factory’s injection bonding flange is also called a looper flange. It consists of three parts: flange gasket, flange seal, and flange plate. When bonding the injection flange, in addition to referring to Title 27 “Plastic Pipes” in this book , How to bond pipe fittings? 》In addition, you should also pay attention to the following aspects:
1. Before bonding, first put the looper flange in the middle of the pipe, and then bond the flange seal. Otherwise, the flange cover will go down after the flange seal is bonded (one end is the social The material is expanded, and one end is a bonded seal).
2. The direction of the looper flange must be correct; because the two sides of the looper flange are different (one side is flat and the other side has grooves), the direction of the force is restricted, and the side with the grooves should face the butt joint. The other side of the flange is bonded and solidified for a certain period of time before tightening the bolts.
When connecting the FRP composite flange to other flanges, you should consider whether the direction of the screw holes is appropriate. If the flange on one side is connected to the pipe, the composite flange plate connected later must be aligned with the screw hole of the flange connected first. Otherwise, the screw hole will The holes are misaligned and the bolt cannot go through.
When tightening bolts, whether it is an injection molded flange or a fiberglass composite flange, it should be noted that the flange axis should be on the same horizontal line, both sides of the flange should be perpendicular to the pipeline, and the gaps should be even, and the bolts should be covered with washers. Increase the contact area and use symmetrical force when tightening bolts to ensure ideal sealing effect.
Link to this article：What are the precautions when bonding and docking plastic flanges?
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