hi everyone, this is the first topic for me.
i have question regarding insulation thickness calculation for pipe going to flare and having a light HC gas flowing inside.
i used this equation Q=(2π*k*L*(T1-T2))/(ln(r2/r1))
Q, heat transfer
k, thermal conductivity
L lenght of pipe
T1, inlet temp
T2, outlet temp
r1, inner dia
r2 outer dia, must be found
k,T1,T2,r1,L are given but to find r2 i have to assume Q/L( heat loss per unit of length)
my question is how to assume of find the heat loss per unit of length