We are contemplating re-rubber lining a number of old (1960s) AWWA C-504 butterfly valves manufactured by the now defunct BIF Co. (New York Air brake).  The butterfly valves range from 24" – 48" (75 lb class) for use in treated drinking water service. 
Rubber lining of the body doesn't seem to be too difficult but I was trying to find a vendor to do the seat fabrication and oversee the rubber installation.  It's kind of a tricky job because there are both hub and disc seats that have to be separately molded and installed in a dovetail gland and then glued.  The original design calls for a filler material to take up the extra space in the gland.  After the seat installation the body is lined and the whole thing is vulcanized.  We will be doing a leakage test to check how the disc seals. 
you may be cheaper to replace the valves rather than having bespoke linings manufactered try ksb for this, they are generally good and will drill AWWA flanges .We are also considering buying new valves but when you're talking about such a large number of them (>50), you need to consider all possible angles. Input from a qualified shop would be helpful to put a dollar value on the refurbishment cost to compare with new.

MORE NEWS