FIELD: diagnostics of loaded materials, determination of value of residual life of loaded structure. SUBSTANCE: according to procedure prolonging service life of loaded structure is loaded with test load and if it does not break down its service life is prolonged by specified time. In correspondence with procedure absolute temperature Ttl of test, duration δt of test, absolute operational temperature T and service period are determined. Test load Ptl is determined from relation 
where Uo is initial energy of activation of break-down; R is universal gas constant; τo s; τ*= 1 s. EFFECT: raised accuracy of determination of test load for prolongation of service life of tested structures serving both under corrosion and without it.
