Cladding Temperature

What is Cladding Temperature?

Cladding Temperature is the temperature of the outer layer. The outer layer means protection on insulation. Some of the outer layer materials are aluminum, stainless steel (SS), and high-density polyethylene (HDPE).

How to calculate cladding temperature?

Cladding Temperature D2 x ln D2 / D1 = 2 x K x (T1-T2) / F x (T2-T) ........................ (i) OR (F x D2 x ln D2 / D1) / (2 x K ) = (T1-T2) /  (T2-T) ................... (ii) Cladding temperature should be less than 60⁰C. Where D1 = Outer diameter of the pipeline (m) D2 = Outer diameter of pipeline over insulation (m) D2 = D1+2t t = Insulation thickness (m) K = Thermal conductivity of insulation (W/m⁰C) F = Surface coefficient of cladding material (W/sqm) T = Maximum ambient temperature (⁰C) T1 = Desired maintenance temperature (⁰C) T2 = Cladding temperature (⁰C) Example: 25mm insulation thickness on 8" pipe,  Insulation thermal conductivity is 0.046W/m⁰C Cladding material is Aluminum Max. ambient & maintenance temperatures are 50⁰C & 100⁰C Solution: 8" pipe outer diameter is 219.1mm i.e. D1 = 0.2191m D2 = D1 + 2t = .2191 + (2 x 25 / 1000) = 0.2691m F = Surface coefficient of aluminum = 5.7W/sqm K = 0.046W/m⁰C T = 50⁰C T1 = 100⁰C Now we put all values in the equation (ii) (5.7 x 0.2619 x ln (0.2619/0.2191)) / (2 x 0.046) = (100-T2) / (T2-50) (0.31529 / 0.092) = (100-T2) / (T2-50) 3.42711 = (100-T2) / (T2-50) Used cross multiply  3.42711 / 1 = (100-T2) / (T2-50) 3.42711 x (T2-50) = (100-T2) x 1 3.42711T2-171.3555 = 100-T2 3.42711T2 + T2  = 100 + 171.3555 4.42711T2 = 271.3555 T2 = 271.3555 / 4.42711 T2 = 61.294⁰C ....................................... Answer Conclusion: result is greater than 60⁰C, hence insulation thickness will be increased.