The nylon will be fine, MLT temps are relatively low. I finally ordered a number of high temp o-rings in various sizes so I have them on-hand now (http://www.brewershardware.com/O-Rings/
). Many brewing websites have them in the typical sizes we use.
Something is always fermenting....
"It's Bahl Hornin'"
Kegged: Sour Saison, Pale Ale, Aggie Ale, Firestone DBA, De Koninck Blonde
Bottled: Belgian Quad (Grand Reserve), Derangement (Belgian Dark Strong)
On Deck: Pliny the Younger