Threaded pipe flanges are similar to slip-on flanges on the shape except the bore of threaded pipe flange has tapered threads, they are matches with the pipes have external threads.  The advantage of thread pipe flange is that it can attached with the pipes without welding like welding neck pipe flanges or slip on flanges, however, a seal weld is also used in conjunction with the thread connection.  

The threaded flanges are always used in smaller pipe size range, from 1/2 inch to 4 inch, since it is difficult to machine a thread for a big size flange. 

Thread flange are suitable for low pressure and temperature systems in which there are no thermal cycles, it is also perfect for the system which has a high level of torque.

PENGTONG sells all kinds of lap joint flange in steel grade ST37, S235 JRG2 or A105. Please email or call us for your flange quote!