Permit Class (SSN-594) — Asbestos in the Thresher/Permit Nuclear Attack Submarines

The Permit class nuclear-powered attack submarines — originally designated the Thresher class before USS Thresher (SSN-593) was lost in the 1963 Atlantic Ocean sinking that triggered the SUBSAFE program — thirteen boats commissioned between 1961 and 1968 — introduced the deep-diving, quiet submarine design that defined American attack submarine development for the next two decades. Permit class submarines introduced a significantly increased diving depth compared to the Skipjack class, the SUBSAFE construction standards that made post-Thresher American nuclear submarines among the most reliable vessels afloat, amidships torpedo tube placement allowing the bow to be optimized for sonar rather than torpedo tube apertures, and the AN/BQQ-2 spherical bow sonar array. Built at Portsmouth Naval Shipyard, Electric Boat, Ingalls Shipbuilding, and Mare Island Naval Shipyard, Permit class SSNs used the S5W or upgraded reactor plant and were constructed during 1960–1968 using naval construction specifications that incorporated asbestos-containing secondary steam system insulation and hull construction materials consistent with the peak asbestos use period in naval construction.

Permit Class Nuclear Steam System Asbestos

Permit class SSNs incorporated asbestos in the nuclear steam system:

• Secondary steam loop pipe insulation — the secondary steam loop aboard Permit class SSNs carrying steam from the reactor steam generators to the main propulsion turbines and ship’s service turbine generators incorporated pipe insulation materials consistent with the early-to-mid 1960s nuclear submarine construction specifications. Engineering ratings working in Permit class engine rooms accumulated background asbestos exposure from secondary steam system pipe insulation during normal propulsion plant operations and maintenance
• Main propulsion turbine and SSTG steam system insulation — the steam supply systems serving Permit class main propulsion turbines and ship’s service turbine generators incorporated pipe insulation and connection insulation materials consistent with the 1960s construction specifications. Machinist’s Mates maintaining steam-powered equipment in Permit class machinery compartments worked in proximity to steam system insulation
• Propulsion plant steam and condensate system insulation — the comprehensive steam and condensate return system in Permit class propulsion compartments — including main steam, auxiliary steam, and condensate piping — incorporated insulation materials consistent with the nuclear submarine construction specifications of the early-to-mid 1960s

Permit Class Hull Construction Asbestos

Permit class SSNs incorporated asbestos throughout the submarine hull:

• SUBSAFE construction materials — the SUBSAFE construction program implemented following the Thresher loss in 1963 imposed rigorous quality standards on Permit class and subsequent nuclear submarine construction, but the SUBSAFE program addressed structural and system reliability rather than insulation material composition, leaving the insulation materials in SUBSAFE-certified systems consistent with the construction specifications of the period
• Crew spaces and working areas — the crew berthing, control room, navigation spaces, and working spaces within Permit class SSN hulls incorporated construction materials consistent with the 1961–1968 construction specifications
• Sonar and fire control equipment spaces — the sonar equipment spaces and fire control equipment rooms housing the AN/BQQ-2 spherical array sonar and associated fire control systems incorporated construction materials consistent with 1960s nuclear submarine specifications

VA Claims for Permit Class Veterans

VA presumptive service connection under 38 CFR § 3.309(d) covers asbestos exposure from Navy nuclear submarine service. Officers and crew members who served aboard Permit class nuclear attack submarines 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.