[2] This lower threshold is due to the potential for serious injury if a person under pressure as low as 2 psig is rapidly decompressed.
[4][5] Section 1-3 "Exclusions" specify nuclear reactor containments, aerospace cabins, caissons are not considered under the ASME PVHO-1 code.
It is noted while "caissons" are under other applicable rules depending on the specific application, the Occupational Safety and Health Administration specifies the chambers in pressurized tunnel boring machines are under ASME PVHO-1 and any chamber used to decompress tunnel workers must meet ASME PVHO-1.
[6] In 2018, prior to the 2023 Titan submersible implosion, William Kohnen, the chair of the Marine Technology Society Submarine Committee, drafted a letter with 38 signatures to respond to OceanGate's public stance on not using existing codes and standards.
[7] The cause of the implosion is still under investigation, but it was noted the other nine submarines that could reach the depth of the wreck of the Titanic were all designed using recognised engineering codes.