Hello Avedhesh

In the case of primary + secondary stresses, ASME Section VIII, Division 2 states that the stresses must not exceed Sps. In section 5.6.1, Sps is defined as 3*S or 2*Yield Stress. This is the definition (as you rightly point out):

d) The allowable limit on the primary plus secondary stress range, PS S , is computed as the larger of the
quantities shown below.
1) Three times the average of the S values for the material from Annex 3.A at the highest and lowest
temperatures during the operational cycle.
2) Two times the average of the y S values for the material from Annex 3.D at the highest and lowest
temperatures during the operational cycle, except that the value from paragraph 5.5.6.1.d.1 shall be
used when the ratio of the minimum specified yield strength to ultimate tensile strength exceeds
0.70 or the value of S is governed by time-dependent properties as indicated in Annex 3.A.

As stated above from Division 2, Sps is either 3S or 2Yield, taken at the average of the hot and cold temperatures.

I agree that primary + secondary stress can occur only at the design temperature (you have a point). However, I am of the opinion that the secondary stresses are derived principally from the attached pipe work as the piping thermally expands. The thermal expansion naturally occurs between two temperatures. Thermal stresses are defined as (among other considerations) as secondary stresses. This is defined in the ‘Hopper’ diagram in Figure 5.1 in Division 2.

Therefore, there is some justification in the way PV Elite handles WRC 107.