Fleet Oiler (AO Class) — Asbestos in Navy Underway Refueling Ships

US Navy fleet oilers — AO class vessels — provided the fuel oil and aviation fuel transfer capability that sustained fleet operations at sea, enabling combatants to conduct extended operations without returning to port for refueling. Major AO class vessels include the Cimarron class (AO-22 through AO-57, WWII-era), the Neosho class (AO-143 through AO-146), the Mispillion class (AO-105 through AO-109), and the Mississinewa class (AO-144). AO class oilers operated with Combat Logistics Force (CLF) replenishment groups, conducting underway replenishment alongside combatants through the connected replenishment (CONREP) method. AO class vessels were powered by steam turbine propulsion — with boilers using asbestos block insulation and steam distribution piping using asbestos pipe covering throughout the engineering spaces. Boiler Tender and engineering ratings maintaining AO class steam plants accumulated asbestos exposure from the boiler room and turbine room insulation systems throughout their service aboard these underway replenishment ships.

Steam Plant Engineering and Asbestos

AO class fleet oiler steam plants incorporated asbestos throughout:

• Fleet oiler boiler room insulation — AO class fleet oilers used steam turbine propulsion with Babcock & Wilcox or Combustion Engineering boilers insulated with asbestos block on boiler casings and asbestos pipe covering on steam mains throughout the engineering spaces. Boiler Tender ratings maintaining the steam plant in AO class oilers accumulated asbestos exposure from the boiler room insulation during their service aboard underway replenishment vessels
• Turbine room steam system piping — steam turbines and reduction gears driving AO class propulsion were served by steam distribution piping with asbestos pipe covering and asbestos gasket materials in steam line connections throughout the turbine spaces
• Cargo fuel oil pumping systems — the large cargo fuel oil transfer pumps used to transfer fuel to alongside combatants used asbestos-containing gasket materials in the cargo pump casings and piping connections throughout the AO class cargo handling systems

Cargo Handling and At-Sea Refueling Operations

AO class service patterns created sustained asbestos exposure:

• Underway replenishment alongside operations — AO class fleet oilers conducted continuous underway refueling operations alongside combatants throughout WWII and Cold War deployments, with engineering ratings maintaining the steam plants through sustained operational periods while cargo ratings transferred fuel through the refueling rigs during alongside operations

VA Claims for Fleet Oiler Veterans

VA presumptive service connection under 38 CFR § 3.309(d) covers asbestos exposure aboard Navy auxiliary vessels. Engineering ratings and cargo handling personnel who served aboard Navy fleet oilers and have since been diagnosed with mesothelioma, asbestosis, or asbestos-related lung cancer may qualify for VA disability benefits.

Source notes: equipment-manifest entries (where shown) are sourced from public-record BUSHIPS (Bureau of Ships) documentation, NARA archives, and the public asbestos litigation record. Manufacturer attributions link to documented asbestos-product histories on AsbestosIndex.com where available. Nothing on this page constitutes medical or legal advice.