Spring bracket PTFE plate
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When making spring brackets, for example F-type spring brackets, is it necessary to add a friction-reducing pad (a polytetrafluoroethylene plate) on top of the load-bearing plate in order to reduce the friction exerted by the pipes on the springs? How great will the benefits be, exactly? I saw that the spring brackets in the pipeline support manual from the Ministry of Chemical Industry did not have anti-friction shims. Under what circumstances can the use of friction-reducing shims demonstrate their advantages? Experts, please give me some advice!
It is mentioned in HGT20644 that the 3 F-type spring hangers can be divided into three types: ordinary load plates (FI type), load plates with polytetrafluoroethylene (FII type), and load plates with rollers (FIII type). When the horizontal displacement of the pipeline exceeds 6 mm, it is recommended to use type FII or FIII. 5.2.5 For F-type spring hangers, when a polytetrafluoroethylene sheet is adhered to the load plate, the following requirements must be met: at room temperature, the peeling strength shall be ≥ 6 N/cm ； Shear strength ≥ 0.4 MPa. When the horizontal displacement of the pipe exceeds 6 mm, a polytetrafluoroethylene load plate is used to reduce the friction between the load plate and the pipe, so that the spring supports can function properly as supports. Friction force: 0.3 for steel against steel, 0.1 for polytetrafluoroethylene against stainless steel. Therefore, the friction force resulting from the use of polytetrafluoroethylene sheets and pipes is between 0.1 and 0.3, in my opinion.
So, when comparing FII and FIII types, which one is used more often?
Regarding one of my previous projects, if the displacement is ≥6mm, the FII type should be chosen; there is no FIII type of spring bracket. Moreover, the FII type has a simple structure, while FIII is slightly more complex; the performance is the same in both cases. FIII will definitely be a bit more expensive, but that’s just my personal opinion.