FRP pipe fittings FRP Flange
Integral flanges are generally flat flanges with equal wall thickness. The advantage of this structure is that the flange ring and the cylinder are integrally formed, and the reinforced glass fiber and fabric are continuous, which can give full play to the high strength and easy forming characteristics of FRP. The disadvantage is that the structure of equal wall thickness and the internal stress distribution of the flange are not Matching, it is difficult to achieve the design requirements of equal strength and equal stiffness; in use, the joint between the flange ring and the cylinder is prone to large deformation under the action of longitudinal stress, and even microcracks and cracking failures.
The bonding flange is formed by separately processing the flange ring and the cylinder body, and then bonding the two together. This structure is widely used. It takes full advantage of the easy forming of FRP. The mold is simple and easy to manufacture. It is suitable for manufacturing large diameter, small batch and special-shaped FRP flanges. But its biggest shortcoming is that the glass fiber between the flange ring and the cylinder body is not continuous, so the strength of the joint is greatly reduced. Even if the corners are reinforced with glass cloth and chopped mat, the bending Moment, shear force, tensile force, etc. are mainly borne by the resin matrix on the bonding surface. As a result, the longitudinal stress of the bonding site is the largest and the strength is strong. It is prone to damage and insufficient safety. It is safe with the increase in the use temperature. The sex should be reduced. Relatively speaking, the loose flange not only has the advantages of the integral flange, but also makes full use of the advantages of the large rigidity of the loose metal flange ring, which greatly reduces the use of FRP flanges due to the method of two bolts after tightening. The blue ring produces leakage caused by bending and excessive deflection. However, as mentioned earlier, the structure of equal wall thickness still does not conform to the stress distribution in the flange. For this reason, we continue to choose a more reasonable flange structure according to the stress distribution in the flange, taking full advantage of the designability and easy forming of FRP performance.
From the aspect of molding process, it is completely feasible to use hand lay-up, cold pressing, pressure injection and other processes to manufacture tapered-neck FRP flanges, but for large, special-shaped, and small-volume hand lay-up FRP flanges, in order to reduce mold investment and shorten production Period, the cone-neck structure can also be evolved into a columnar structure. The diameter of the column is equal to the diameter of the large end of the cone, and the height is unchanged. The structure only slightly increases the consumption of raw materials, does not decrease the performance, and is more convenient to manufacture.
The production, inspection and acceptance of FRP tees are in accordance with the HG/T21633-1991 “Glass Steel Pipe and Fittings” standard. The connection size standard of FRP Tee is in accordance with HG20592-1997, HG20615-1997, HGJ44-1991, HG5010-1958, ASME B16.5-1996, ANSI B16.5-1988 standards, or designed and manufactured according to customer requirements.