Thermocouple placement- UCS 56 (d) (2)

[MECH993]

Hello Experts, request your comments on below query.
As per UCS 56 (d)(2) temperature gradient shall not exceed 250 F within 15 feet length interval.
We have as vessel of 125" OD, the query is length interval for thermocouple placement along circumference is calculated based on circumferential length (32.5 feet) or diametrical length (10.33 feet).
Reference of interpretation if any is appreciated.

Yog P

 

[TGS4]

Along the surface of the vessel - so that would be in the circumferential and longitudinal diections.

 

[oknow]

Maybe unlikely because of it's size, if other Code Items are in the oven during PWHT then refer to UW-40(c). It has been known to be overlooked.