Of course there is a thickness formula for piping according to EN 13480 but take care the allowable pressure is calculated not given as per ASME VIII or B31.3.
e=Pc*D0/2*f*z or e=Pc*Di/2*f*z+2*Pc for T<120°C
I found an other formula for high tempreture
e = PS*Do / [20*f*z+P*(2-z)]
and for room tempreture
e = PS*Do / 20*f*z i.e. the one you gave the first time?