Steam Valve Stem O-Ring — EPDM 0040-20 A small EPDM o-ring that seals the steam valve stem where it passes through the valve body. It's an inexpensive part, but it's also one of the most common sources of a steam wand that hisses or drips at the handle rather than the tip. SPECIFICATIONS O-RING 0040-20, EPDM, 1.9 mm thick, 4.2 mm ID COMPATIBILITY Fits: Steam valve stems using the 0040-20 EPDM o-ring size INSTALLATION Quick swap once the steam valve stem is out — a five-minute job for most techs. PRO TIPS Steam leaking around the valve knob, not the wand tip, while steaming is the classic symptom of this o-ring failing — don't waste time chasing the wand or tip assembly if that's what you're seeing.