Issues related to the matching of loose-flange fittings in lined pipes
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This post was last edited by Clouds of flowing water shine on 2020-6-8 at 10:13. The medium used in this project is not highly toxic; it is flammable under categories A and B, and it has corrosive properties. The pressure is low, and the temperature is below 150 degrees. Linered pipes are widely used, with pipes and fittings connected using flanges; the client requires that some of these connections be made using loose-flange connections. 1. Where are loose flanges used? How to inform the supplier? 2. How is the bolt length required for PL connections of lined pipes and pipe fittings calculated? How is the bolt length calculated at a loose-flange connection? 3. The design institute recommended using the special grade 35CrMO with anti-corrosion treatment, while the owner said that the commercial grade 8.8 would be sufficient. 4. The design institute recommends the use of washers in accordance with the standard GB/T97.2, but their strength does not match that of the bolts. The owner directly said it’s not needed. What are the advantages and disadvantages of using washers? How to choose a model?
1. Where are loose flanges used? How to inform the supplier? On piping diagrams, pipes that are generally horizontal or vertical are usually not taken into consideration; instead, those pipe sections that have connections and require a specific orientation, such as those at elbow locations, are considered. In the annotations with dotted lines on the drawings provided to the supplier, note 2: How is the bolt length required for connecting the lining pipes and pipe fitting flanges (PL) calculated? How is the bolt length calculated at a loose-flange connection? Depending on your medium, raised and recessed flanges should be used. Depending on the flange standard adopted, the bolt length can be calculated based on the flange thickness; or relevant tables can be found in chemical industry standards. The design institute recommends using 35CrMO of special grade with anti-corrosion treatment, while the client says that 8.8 grade commercial material will suffice. Based on the properties of the medium, since ordinary owners are not very knowledgeable in this area, it is better to opt for insurance. 4. The design institute recommends the use of washers, in accordance with the standard GB/T97.2; however, the strength of these washers does not match that of the bolts. The owner directly said it’s not needed. What are the advantages and disadvantages of using washers? How to choose a model? There are tables available in the standards for chemical industry flanges, and each gasket has corresponding standard requirements.
1. Specifications and standards for the connection to the equipment. 2. Examine the flange and pipeline samples. 3. Decide based on whom to follow – check the contract, the drawings, and the project communication documents
Not only enthusiastic but also professional – great job! ! ! ! Feel free to come and communicate more in the Piping and Valves section when you have time!
Too kind of you. I’ve worked on similar pipelines before, and these are some insights I’ve gathered from that experience
Then which side are you on? Worried about everything related to the design institute and the client, haha