This paper presents thermomechanical fatigue tests of 16Mo5.3b steel test specimens, in temperature range 60oCĂ·540oC, with total strain control in wich cycle of temperature variation, on ring surface test specimens. Thermal condition of test is without soaking period at maximum temperature 540oC. Using a modern process of experimental datas statistical analysis is tracing the material thermomechanical fatigue curve, and base on this is established the shell type structures durability, like coking chambers.