Venting the Line

I traced the cast-iron conduit down the subfloor trench until the line met an inline sediment trap. Bolted to its flank was a heavy brass petcock, encrusted beneath a hard shell of dried mineral scale. I drew the straightened wire probe from my pocket and knelt on the cold concrete floor. Working methodically, I chiseled the white crust away from the threads, clearing the groove until clean metal showed through. I set the probe down and clamped my fingers around the square brass lug. Steady torque, held without surging. The seam gave way with a dry snap, rotating a precise quarter turn. A brief hiss of stale air vented into the quiet channel.