The value of angular misalignment should be reduced for increasing flange size. A maximum of perhaps 1-3° is acceptable (again depending on ferrule size) in a rigid scenario where no deflection can take place and the gasket must absorb this mis-alignment. In other words, the misalignment percentage should be minimised regardless of the ferrule diameter. Possible gaps due to misalignment would be 3 millimetres for 4 inches at one degree.
The BPE union adapts well to misaligned ferrules. The 20° face and clamp profile enables the ferrules to be aligned up to a certain point; however this is not ideal due to
the use of an elastomer gasket as the gauging face. Mis-aligned ferrules would result in higher point loads on the gaskets, thus resulting in localised gasket intrusion and wash-away of the elastomer at these points.
Due to the Advanced Couplings ‘omega’ design, the clamping force is delivered at the correct gauging point on the ferrules (REF ASME-BPE) in comparison to the standard tri-clover design. Since the load is applied on a point/plane rather than a plane/plane configuration, the out-of-flatness or manufacturing defects are more tolerable to this design.
Again, note that you should never use a clamp to pull pipes and components into alignment.