Dear experts,

I am still in the learning phase. Bear with me.
(My main task is process simulation but slowly trying to develop myself into a process engineer)

While preparing a datasheet for pressure vessels, what would be sound engineering practices to specify the design pressure and temperature? For the past 2 years, I have prepared datasheets for various process vessels with 10-25% higher than operating pressure (for distillation column and reactors- much higher), and no seniors have raised a question about it- probably because those were only preliminary datasheet. But I want to know from professionals, what would be the best approach to specify the design pressure/temp?
(PS- I tried to ask my seniors but could not get a concrete answer)