Hello Fellow Stressers!!!

How to interpret the below statement for SSI (Sustained Stress Index) of Welding Tee (Sketch 2.1). I believe the SSI is equal to SIF?

The lower SSI (e.g.,0.75SIF) can only be used for Sketch 1.2 (Closely Spaced mitered bend) as per the statement below?

"(d) Where sustained stress or moment factors are required by the applicable Code (e.g., ASME B31.1, ASME B31.3), and in lieu of more applicable data, for components of Sketches 1.1, 1.3, 2.1, and
2.2, the directional sustained stress or moment multiplier can be taken as the component stress intensification factor. For all components of Sketch 1.2, the directional sustained stress or
moment multiplier can be conservatively taken as the smaller of (1) and either (2) or (3) below
(1) 0.75 times the applicable stress intensification factor
(2) (t/T) times the square root of the applicable stress intensification factor when t/T > 1
(3) the square root of the applicable stress intensification factor when t/T ≤ 1
The sustained stress or moment factors should always be used with the section modulus of the matching pipe and should not be less than 1.0."

Thanks in advance,