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What Is The Flange Class And Schedule

Apr 23, 2020

       You may heard of flange class and flange schedule,sometimes confused what flange class and flange schedule is,are they the same?

        You maybe know a little about flange,flange class is a pressure-temperature rating that defines maximum allowable working pressure of the flange. 

        Flange class is usually in 150#, 300#, 600#, 900#, 1500# and 2500# in standard ASME/AWWA,large diameter flanges that is 24″ to 60″ are available up to 900# class.The rating is higher,and the flange can withstand higher pressure and temperature.Check the following pictures,there are some size in class 150 and class 300.you can see there are some difference in diameter for same size in different class.

        The same situation in other standard,like EN 1092-1 PN10,PN16,PN25,PN40,JIS standard Flange 5K,10K,16K.20K. All these are flange class.

Whether the same class flange could have a different schedule?Of course,if same class flange is used with different schedule pipe, the flange schedule will also be changed according.

        When flange class and schedule appears in the same request description.you should be able to understanding means.if client request weld neck flange,but didn’t offer flange schedule in request,should check with client what pipe schedule/thickness is welded with the weld neck flange.If flange schedule is wrong to produce,there will be a miss matching in internal diameter of flange and pipe.