BS7608:1993 rule - Class B and Class F stress-range for 100Million cycles endurance

British Standard BS7608:1993 is superseded/withdrawn - but is used during research because its inner workings bridging from "experimental (data)" to "design (specification)" are revealed.

According to the mathematical relationships presented in its Table 14 for the 95% / 2.S.D. "design basis" curves:

to reach

the allowable maximum cyclic stress ranges would be

To more than double the permitted cyclic stress intensity would be extremely beneficial.
56.4MPa / 25.8MPa => 2.18 times.
Considering an S355 (355MPa nominal yield stress) structural steel:
where the former 25.8MPa permitted cyclic stress range would be restrictive, a permitted 56.4MPa cyclic stress range is getting close to permissible static stresses given design safety factors so is only slightly restrictive.

(R. Smith, 16Jan2021)