Piping System Engineers – Have you ever come across the need to supply rubber expansion joint/control units in a piping system where the flanges you want to attach have ASME B16.47 Series B drilling? If so, then you will know that the conventional control rod setup can be challenging as the attachment area for a traditional triangular control rod plate is greatly reduced. With ASME Series B16.47 Series B drilling the bolt circle for the flange is closer to the O.D. of the pipe than Series A drilling.
So what design can be used for ASME B16.47 Series B drilling?
The best rubber expansion joint design to consider is an ITR (Interior Tie Rod) design. As an example, a system designer has an application for an 30″ I.D. x 24″ OAL triple arch rubber expansion joint with one end having ASME B16.47 Series A drilling and one end having ASME B16.47 Series B drilling. Control rods are used in the example as the piping system is unrestrained. When thicker ring/rod plates connect the rubber expansion joint to the adjacent mating flange, an ITR design is used. This design can be used while containing the thrust loads and movement of the expansion joint under pressure (with the use of the connecting rods).
Using the ITR design will eliminate the complication of a traditional control rod set up on the back side of the mating flange where the rod plates do not have enough webbing from the I.D. of the plate to the I.D. of the holes on an ASME B16.47 Series B flange. The only other option a client might have when dealing with ASME B16.47 is a control rod setup where thick fabricated split flange plates are supplied so that the resultant thrust loads from the rubber expansion joints are evenly distributed to every bolt hole (see photo).
In conclusion, the best design for ASME B16.47 Series B bolting when using a rubber expansion joint is the Interior Tie Rod Design configuration. To learn more about this design, click here.