The Machinist’s Mate Engine Room Overhaul Cycle

U.S. Navy steam-propulsion ships underwent depot-level overhauls on roughly 5-year cycles, with each ship typically experiencing 3-5 major overhauls across its service life. Each Regular Overhaul (ROH), Selected Restricted Availability (SRA), or shipyard-period was the most intense asbestos-exposure window of the Machinist’s Mate rating — when the entire main propulsion plant was torn down, inspected, refurbished, and rebuilt.

A typical engine-room overhaul lasted 3-12 months and involved extensive asbestos disturbance across virtually every category of engine-room equipment.

Engine room overhaul scope and asbestos exposure

Main propulsion turbine overhaul

  • Turbine “lagging” tear-out — removing the asbestos thermal insulation jacketing the main and auxiliary turbines, including high-pressure (HP) and low-pressure (LP) turbines, generator turbines, and main feed pump turbines. This was among the highest-fiber-release activities in the entire Navy engineering trade.
  • Turbine casing inspection and rebuild — opening turbine casings for blade inspection, nozzle inspection, and rotor balancing; replacing all asbestos gaskets at every flange of the turbine casing
  • Turbine packing replacement — replacing the asbestos packing at turbine shaft penetrations (HP and LP shaft seals)

Main condenser overhaul

  • Condenser end-cover removal and gasket replacement — disturbing the asbestos gaskets sealing each end of the main condenser; major asbestos disturbance event
  • Condenser tube cleaning and replacement — pulling and replacing condenser tubes; disturbing asbestos block insulation on the condenser shell
  • Waterbox inspection and gasket replacement — additional asbestos gasket work at waterbox connections

Reduction gear overhaul

  • Reduction-gear case inspection — disturbing asbestos gaskets and packing at the reduction-gear case penetrations
  • Bearing inspection and replacement — disturbing asbestos packing at thrust-bearing housings

Evaporator / distilling plant overhaul

  • Evaporator tube-bundle pulls — disturbing asbestos block insulation on the evaporator shell and asbestos gaskets at the tube-bundle penetrations
  • Distilling condenser overhaul — additional asbestos block and gasket disturbance

Auxiliary machinery overhaul

  • Auxiliary turbine overhaul — generator turbines, fire-pump turbines, ballast-pump turbines, fuel-oil-pump turbines — each with asbestos lagging, gaskets, and packing
  • Pump overhaul — feed pumps, fire pumps, bilge pumps, condensate pumps, fuel-oil service pumps, lube-oil pumps — each with asbestos gaskets at flanges and asbestos packing at shaft penetrations
  • Compressor overhaul — air compressors, refrigeration compressors, hydraulic compressors with asbestos-bearing gaskets and seals

Steam and water piping overhaul

  • Steam piping rip-out and re-installation — main steam, auxiliary steam, exhaust steam, extraction steam, gland-leak-off steam, dump steam piping. Asbestos pipe insulation disturbed throughout.
  • Feed and condensate piping rip-out and re-installation — feed water, condensate, deaerating-feed-tank, drain piping. Asbestos pipe insulation throughout.
  • Fuel-oil piping rip-out and re-installation — main fuel-oil, fuel-oil-service, fuel-oil-transfer piping
  • Lube-oil and seawater piping — additional asbestos pipe insulation

Machine-shop gasket fabrication

  • Custom gasket fabrication in the engineering-space machine shop — cutting asbestos sheet gasket material to fabricate gaskets sized for the equipment being overhauled. Sheet-gasket cutting at the machine-shop bench generated substantial respirable asbestos dust.

Cumulative exposure across a MM career

Across a 20-year Navy career, an MM typically experienced:

  • 2-4 major engine-room overhauls (3-12 months each) at public shipyards
  • 6-10 in-port engineering availabilities at homeport (shorter, less intense)
  • Continuous routine maintenance at sea — gasket replacement, valve packing, pipe insulation patching as needed
  • Steam-plant casualty response — boiler casualties, condenser tube failures, steam leaks involving immediate disturbance of asbestos materials in casualty response

This cumulative exposure is sufficient to support meritorious VA service-connected disability claims and civil claims against asbestos product manufacturers.

Post-1996 MM career (post-BT-consolidation era)

In 1996, the Navy merged the Boiler Tender (BT) rating into Machinist’s Mate (MM). Post-1996 MMs serve both boiler-room and engine-room billets, accumulating exposure across the full propulsion plant.

If you served as a Machinist’s Mate

If you served in the U.S. Navy Machinist’s Mate (MM) rating at any point during the asbestos era — including post-1996 MMs whose assignments included both boiler rooms and engine rooms — and have since been diagnosed with mesothelioma, asbestosis, lung cancer, or another asbestos-related illness, you may have legal rights.

Free, confidential case evaluation: Speak with O’Brien Law Firm — (314) 936-2956

All consultations are free. No fee unless a financial recovery is made on your behalf.