Screwed flanges

Pipe runs are normally made up from lengths of pipe, incorporating standard fittings for joints, bends and tees. Joints are usually welded but small sizes may be screwed. Flanged joints are used where this is a more convenient method of assembly, or if the joint will have to be frequently broken for maintenance. Flanged joints are normally used for the final connection to the process equipment, valves and ancillary equipment. 

Screwed flanges, Figure 13.33d are used to connect screwed fittings to flanges. They are also sometimes used for alloy pipe which is difficult to weld satisfactorily. 

To test the fit, place the nipple on the bottom flange with a Teflon flange gasket and the negative electrode in place. Place a Teflon gasket on top of the screw flange and slip the felt into the coupler. 

Three-hundred-pound steel flanges can be bolted to cast-iron valves having either class 250 cast-iron-integral or screwed flanges, without any change in... 

End type (screw, flange, welding, etc.). If flange end, specify raised face or ring-joint type. 

Ordinary steel pipe is suitable for handling solvents. Underground piping should be welded. Surface piping may be screwed, flanged or welded. Compressed-cork gaskets are suitable for pipe flanges. 

Type (welded flanges/screwed flanges), diameter, length... 

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