677.463.051.125 and M. S. Grachev** A calculation scheme is proposed which allows establishing the effect of creep on the sag of the spinneret plate in a spinneret feeder and its lifetime. The sag increases and the feeder lifetime decreases with an increase in the stresses arising when the plate is loaded.Spinneret feeders [SF] installed in units for production of glass, silica, and basalt fibres are welded box-like thinwalled structures. The temperature in the region of 1250 to 1450°C is maintained in elements of the SF. The ratio of the working temperature to the melting point is equal to 0.7-0.8, which makes it necessary to perform a calculation for creep [1].Creep of platinum alloys has been widely investigated by foreign and domestic specialists [2][3][4]. It was found that the creep curves of platinum alloys are similar to the creep curves of pure metals. It was noted that platinum alloys with rhodium have a sufficiently long period of steady creep and the dependence of the creep rate () on the stress (σ) is described by the expressionwhere A, n are constant coefficients which are a function of the properties of the material, the temperature, and the conditions of conducting the experiments.In our case, in the calculation for creep, determining the sag of the spinneret plate and establishing the lifetime of the SF with consideration of admissible movements is the most important.An increase in the spinneret plate sag perturbs the cooling conditions in the zone beneath the spinneret and consequently increases the fibre end breakage during spinning.The spinneret plate SP can be considered as a rectangular thin but rigid plate uniformly loaded by distributed pressure and fixed along the entire contour. We will assume that the total sag of the bottom at some point in time will be composed of the sag that arises on loading and the sag due to creep.As the calculations in [5] showed, in real structures, the stresses that arise in loading are much less than the creep limit for the plate, which makes it possible to determine the sag in loading with well-known materials resistance equations. We will select a system of coordinates where plane xy would coincide with the midplane of the plate and the origin of coordinates will coincide with the center of gravity (Fig.