Lead Castings

The chain hoist rattled on its rusted overhead rail, dropping two inches every time the exhaust draft surged through the hatch. Temuroglu braced his steel-toed boots against the gantry edge, his hands clamped on the suspension rig of the eighty-pound lead damper casting. He wanted the six sealing studs threaded into the manifold collar before the primary cycle ended. If the intake pressure inverted while the conduit stood bare, half a ton of pressurized exhaust would rip into the residential floor directly overhead.

Below him on the grating, the Tuner leaned his back against the support stanchion. His hands shook against his brass pickup needles, his skin gray under the faint green throb of the luminescence tubes. The feedback loop from the previous breach had left his pupils wide, his pulse visibly jumping against the tendon in his throat.

"The resonance is climbing," the Tuner shouted up through the iron ladder. "Four hundred hertz on the casing. The tone is climbing because the throat is narrowing."

Temuroglu felt the words through the iron pins anchored behind his ears. The vibrations traveled along his jawbone, registering as a sharp, dry rasp. He did not look down. He locked the chain brake with his heel and shoved the lead slab forward into the mouth of the exhaust duct.

Altantay stood on the opposing platform with a pneumatic torque driver resting on her shoulder. She wiped a smudge of powdered graphite from her chin and pointed her grease marker at the lower rim.

"The lower bolt holes are oval," Altantay said. "The heat did not do that. The flange has been pulled inward."

Temuroglu lowered his heavy iron spanner onto the flange lip. He bit down on the handle, letting his teeth contact the cold iron to read the structural load. The steel was not merely settling. A rhythm pulsed through the casing, striking three short beats followed by a long, wet draw. The metal beneath the plate was flexing, expanding and contracting like cartilage.

"Grab the guide pins," Temuroglu told her. "We drop the plate on the count."

"The casing is twelve millimeters out of round," Altantay warned, though she racked the slide on her driver and took position over the upper hinge pin. "If the lead binds halfway across the seat, we will never pull it back out."

"It goes on now," Temuroglu said.

He released the hoist clutch. The lead slab swung downward into the recess.

The moment the plate met the lip, the suction did not whistle. It pulled.

The air pressure inside the manifold dropped so fast that Temuroglu felt the seal in his ears snap. The heavy lead casting, intended to settle under its own weight, slammed violently against the seat with the force of a hydraulic ram. The iron chain above them groaned, link grating against link as the draft tried to drag the entire casting down the dark throat of the pipe.

The Tuner scrambled backward along the catwalk, his spectrogram cables tangling around his knees. "The pressure is negative eighty kilopascals! That is impossible for a gravity exhaust! It is drawing air from the lower baffles!"

Temuroglu threw his weight onto the upper lever arm. The lead slab buckled.

Lead was supposed to deaden sound and resist sheer strain, but under the intake’s grip, the one-inch plate bowed inward like tin foil. The center of the metal drew into a concave dish, straining toward the dark interior of the conduit. Across the seam, the lower two bolt holes twisted out of alignment, the threaded studs scraping sparks against the lead casing.

Altantay hammered the first guide pin into the upper corner. The steel rod held, but the lower corner kicked out three inches, screaming as the metal dragged across the rim.

"The studs will shear!" Altantay yelled, bracing both arms against the top clamp. "The torque driver cannot bridge the gap!"

Temuroglu dropped his hammer. He jammed the tapered handle of his heavy forged spanner straight into the misaligned bolt sleeve between the conduit rim and the buckled casting.

The wrench bit into the gap. Temuroglu levered the steel handle with both arms, his boot heels skidding on the oily grating as he threw his full body weight against the tool. The leverage forced the bowed lead plate back against the intake seat by a fraction of an inch. The lower bolt hole snapped into line with the threaded stud on the manifold.

"Drive the lower pin!" Temuroglu shouted.

Altantay dropped to one knee on the vibrating gantry. She swung her copper-headed mallet, striking the tapered lower pin once, twice, driving the wedge deep into the sleeve.

The conduit answered with a shudder that threw a shower of black scale from the roof beams. Through the steel wrench in his hands, Temuroglu felt the resistance turn from an airy vacuum into solid, muscular tension. Something inside the pipe clamped onto the spanner's forged jaw.

The shock traveled through the metal into his wrists, vibrating with the exact cadence of a jaw snapping shut on an iron bit.

The chrome-vanadium steel of the spanner screamed. The forged jaw of the wrench split clean down the center line, shearing the metal grain with a dry crack that jarred Temuroglu's collarbone. The broken handle whipped back, missing his temple by an inch and ringing off the gantry rail.

Temuroglu did not wait to watch the tool fall. He grabbed the pneumatic driver from Altantay's side, dropped the socket over the center stud, and pulled the trigger.

The air motor shrieked, driving the heavy bronze nut down the threads. It crushed the lead rim flush against the intake seat. He shifted the socket to the remaining four corners, rattling each nut home until the torque limiter broke with a series of sharp metallic clicks.

The roaring draft inside the pipe cut off instantly.

The silence that followed was heavy and thick, smelling of hot lead, sheared steel, and the sweet, alkaline musk of old plaster. The luminescence piping overhead stabilized, its sickly green flicker smoothing out into a steady pale glow.

Altantay sat back on her heels, wiping sweat from her brow with the sleeve of her coat. She picked up the severed half of Temuroglu’s spanner from the steel mesh.

"A sixty-mark forged wrench," Altantay remarked, turning the mangled tool in her fingers. "Dispatch will classify this as technician negligence. They will dock your shift pay unless you file an equipment loss report with three counter-signatures."

"Let them dock it," Temuroglu said, his voice flat in the dead air.

He stepped over to the catwalk edge where the discarded sheet of the old damper plate lay propped against the bulkhead. He had pulled it from the lower lip of Conduit 4-B before hoisting the new casting. The plate was warped into a crude crescent, its outer edges scored by the scraper they had used earlier.

Temuroglu knelt beside the scrap metal. He took his pocket flashlight from his harness and clicked it on, angling the beam across the underside of the old damper.

Where the steel rim had buckled inward into the gum-shaped socket, the lead backing had not cracked cleanly. The soft metal was punctured by a neat, curving arc of white, calcified pegs. Each peg was rooted two inches deep into the lead matrix, smoothed and crowned like human molars, their enamel stained with black pipe grease.

Temuroglu reached out with a gloved thumb and pressed the tip of the center molar. It did not budge. The tooth was grown directly into the metal, anchored to the lead by fibrous white roots that pulsed with a faint, dying warmth.

Altantay dropped the broken wrench onto the grating. She knelt on the damp steel, her knuckles grazing the edge of the teeth, her voice dropping into the hollow between the pipes.

"The intake is not drawing air to ventilate the block," Altantay said. "It is rooting itself into the foundation."

Temuroglu stood up and hooked his remaining tools into his harness. "Pack the chime cases. We are cutting the primary risers next."