API-594 check valve rev. history - dual security

[NPS1978]

Wondering if anyone knows in which revision the requirement for dual disc nut security was added? This is the statement that a single tac weld or lock nut alone is not sufficient to secure the disc to hanger arm. It's a terribly written sentence.

Last revision added anti rotation device, any help pointing out which rev added this dual security statement? FWIW the British Standard requires cotter pin and allows it alone, Cotter pin isn't even mentioned in API 594.