Knox Class Frigate (FF-1052) — Asbestos in the Cold War Escort Frigate

The Knox class frigates — 46 ships built between 1969 and 1974, commissioned as destroyer escorts (DE) and redesignated as frigates (FF) in 1975 — were the United States Navy’s primary Cold War ocean escort vessels. The class, designated FF-1052 through FF-1097, served as antisubmarine warfare (ASW) escorts for carrier battle groups and underway replenishment groups throughout the Cold War. Knox class frigates were built primarily at Avondale Shipyards in New Orleans and Todd Shipyards in Seattle. The Knox class used a single-shaft steam propulsion arrangement powered by a Westinghouse geared steam turbine unit driving one propeller shaft, with two Babcock & Wilcox boilers providing steam to the main propulsion turbine. The single-shaft arrangement distinguished Knox class frigates from the twin-shaft destroyer classes of the same era. Knox class frigates incorporated asbestos-containing boiler insulation, steam plant pipe insulation, and equipment gasket materials throughout their propulsion plants consistent with Cold War naval construction specifications, creating exposure for engineering ratings who maintained Knox class steam plants throughout the class’s service.

Knox Class Steam Plant Asbestos

Knox class frigates incorporated asbestos in their Westinghouse turbine and B&W boiler propulsion arrangement:

• Babcock & Wilcox boiler casing and drum insulation — the two Babcock & Wilcox boilers aboard Knox class frigates incorporated asbestos-containing insulation on the boiler casings, steam drum surfaces, and combustion chamber walls consistent with the boiler construction specifications of the late 1960s and early 1970s. Boilermen performing boiler maintenance and inspection aboard Knox class frigates worked in direct proximity to the asbestos-containing boiler insulation throughout their engineering watch assignments
• High-pressure steam main pipe insulation — the high-pressure steam mains running from the Knox class boilers to the Westinghouse main propulsion turbine unit incorporated asbestos-containing pipe insulation on the steam main piping throughout the engineering spaces. Machinist’s Mates and Boilermen working in the engine room and fireroom of Knox class frigates accumulated background asbestos exposure from the steam main pipe insulation during engineering watch standing
• Westinghouse main propulsion turbine casing insulation — the Westinghouse geared steam turbine unit providing main propulsion power on the Knox class single shaft incorporated asbestos-containing insulation on the turbine casing and steam chest surfaces. Machinist’s Mates performing main propulsion turbine maintenance aboard Knox class frigates worked in direct contact with the turbine casing insulation during turbine inspection and maintenance operations
• Auxiliary steam system pipe insulation — the auxiliary steam systems serving the Knox class engineering plant — steam for hotel services, distilling plant, and auxiliary machinery — incorporated asbestos-containing pipe insulation throughout the engine room auxiliary steam piping. Engineering ratings working in Knox class engine rooms accumulated background asbestos exposure from the auxiliary steam system pipe insulation throughout their engineering space assignments

Knox Class Engineering Space Gaskets and Packing

Knox class frigate engineering maintenance involved asbestos-containing gasket and packing materials:

• Boiler steam drum and water drum manhole gaskets — the steam drum and water drum manholes on Knox class Babcock & Wilcox boilers used asbestos-containing compressed gasket materials at the manhole cover sealing faces. Boilermen entering Knox class boilers for internal inspection or tube cleaning encountered and replaced the asbestos-containing manhole gasket materials during each boiler entry operation
• Main propulsion turbine steam joint gaskets — the steam joint connections on Knox class Westinghouse main propulsion turbine casings used asbestos-containing compressed gasket materials at the turbine casing flange faces. Machinist’s Mates performing turbine casing work aboard Knox class frigates encountered asbestos-containing turbine gasket materials during turbine maintenance
• Boiler feed pump shaft packing — the boiler feed pumps aboard Knox class frigates used asbestos-containing shaft packing in pump stuffing boxes. Machinist’s Mates repacking Knox class boiler feed pump stuffing boxes encountered and replaced the asbestos-containing shaft packing during each pump maintenance cycle

VA Claims for Knox Class Veterans

VA presumptive service connection under 38 CFR § 3.309(d) covers asbestos exposure from Navy steam propulsion plant service. Machinist’s Mates, Boilermen, and engineering ratings who served aboard Knox class frigates 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.