Bolt length for non-metallic flanges
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As the title suggests, this project involves the use of lining pipes, steel-glass pipes, PE and other non-metallic pipes, as well as flanges to connect them. How should the length of the bolts used be determined?
The bolt length for non-metallic flanges is usually determined based on the thickness of the flange, the thickness of the gasket, and the height of the nut. It can be calculated following these steps: 1. Measure or consult relevant information to obtain the thickness of the flange. 2. Determine the thickness of the gasket to be used. 3. Refer to the relevant standards or measure the height of the nut. 4. Add the flange thickness, gasket thickness, and nut height together, and then add an additional length (usually half the bolt diameter) to ensure there is enough thread for the nut to grip tightly. This total is the required bolt length. Ensure that all connectors are compatible and meet standard requirements to guarantee the safety and integrity of the connections. .
It is recommended to specify “full set of flanges, bolts, and gaskets” when placing the order. For reference.
Knowing the thickness of the flange and the thickness of the gasket allows one to calculate the length of the flange. Generally, non-metallic flanges are thicker than metal flanges of the same grade; adding 10 mm to the bolt length used for metal flanges should be sufficient. Refer to standards such as HG20613, etc.
The bolt length specified in HG/T 20613-2009 \"Fasteners for Steel Pipe Flanges\" can be used as a reference; then the thickness of the non-metallic flange being used should be compared with that specified in HG/T 20592-2009 \"Steel Pipe Flanges\", and any necessary adjustments to the thickness can be made accordingly. The flanges of the lining pipe comply with the HG/T 20592-2009 standard \"Steel Pipe Flanges\". The flange thickness for reinforced polypropylene (FRPP) pipes is specified in HG 20539-1992 \"Reinforced Polypropylene (FRPP) Pipes and Fittings\". The flange thickness of glass fiber reinforced plastic pipes is specified in HG/T 21579—1995 \"Polypropylene/Glass Fiber Reinforced Plastic (PP/FRP) Composite Pipes and Fittings\".
Refer to the steel flange fasteners; determine the difference in the total thickness of the flanges, and account for this difference in the length of the steel flange fasteners.
I took a quick look at the specifications; for example, the flanges of reinforced polypropylene pipes need to be 5 mm longer than those specified in HG/T 20613-2009 \"Fasteners for Steel Pipe Flanges\".