Can any one reply me How do you define X-ray as 10% or 20% or 5% or 100% with respective of service, class, SCH, material and temp/pressure and Stress relieve (PWHT).

What document you reference with?

For Example: Carbon Steel PIP piping spec 1cs1s01
Temp -20F to 800F (OT=100) range with press range -285psig to 80 psig (OP=80)
corrosion 0.063 in
class 150
pipe = 6 inc STD sch Ej=.85
serive = refinary Gas
PWHT = ?
x-RAY= ?

I got few reference that hardness for carbon steel should not exceed 200BHN and PWHT > 3/4 inch (0.75)with temp 1190-1200F holding time of temperature is 1hr/in with Pnumber =1. (asme 31.3)

My Question:-reference doesn't talk about class/service and my data is not close to given reference data. I don't what to go by experience guess or education guess I like perfect document reference. Can any one help me please with your reply.

You will find the answer in the ASME B31.? Code that applies to your project