A new twist on an old product

Flanges that rotate. Magic flanges. I picture the scene in Forrest Gump where Forrest greets with incredulity his old friend, “Lt. Dan, you got legs! Magic legs…” Perhaps it is a stretch for me to bring such a comparison to the humble van stone flange, but to those who install them it is a refreshly trouble-free fitting, worthy of such praise.

Field fit-up
A van stone flange is fabricated by lapping the ‘neck’ or tangent of a bellows over the flange face. This allows the flange to rotate prior to tightening the bolting.

Piping can settle or shift, resulting in misaligned mating flanges. Van Stone flanges will rotate until aligned. In addition some manufacturers have a 1/8 to 1/4 inch gap between the flange ID and bellows tangent allowing additional misalignment adjustment.   

Corrosion protection

Another bonus is the flange does not see the media. The bellows is the entire wetted surface. Applications that call for all stainless steel components due to corrosive media can use less expensive carbon steel flanges with a stainless van stone bellows.

One note of caution – the van stone surface creates a raised face and is a sheet metal surface so gasket accordingly.

Cost savings

Oh yeah, did I mention that van stone flanges are less expensive to manufacture than fixed, welded flanges? You should expect a discounted price from the cost of a traditional fixed flange expansion joint.

Magic flanges. What will they think of next?

Next month – Why an expansion joint works: Part II