Many customers can not make clear the distinction between flange adaptors(adapter) and dresser couplings, this article introduce their difference briefly.

The first reason why many people may confuse flange adaptors and dresser couplings is that their name is totally different. In our company, we call flange adaptors as VSSJA flange type loosen expansion joint, in GB/T12465-2007, it is also called AF type compensator; and our company calls dresser couplings as SSJB follower type loosen expansion joint, in GB/T12465-2007, it is also called AY type compensator.

The second reason is that they did not make clear the structure or do not know the drawing. The two expansion joints' connection looks like two flanges at the both end. Following are the pictures of flange adaptors and dresser couplings, please check them carefully:

Left: Flange Adaptor; Right: Dresser Coupling

1. From upper two photos, one end of flange adaptors has separate holes beside the bolts holes in the middle ring, but there are no extra holes at the end of dresser couplings. It is very easy to be found, actually, we call the "flange" of the dresser coupling is follower, it is not flange.

2. We can also find that there is only one rubber gasket in the flange adaptors, there are two rubber gaskets at both ends of dresser couplings, because the separate holes of flange adaptors are used for connecting with faced flanges, with rubber gasket ends connecting is the sleeve type, the pipe insert the middle ring, sealing function need to be made by rubber gasket.