CALCULATION OF NORMAL TEMPERATURE DIFFERENCE ON MAIN GAS PIPELINES WITH LONG SERVICE LIFE

Abstract

In the global pipeline transport, including main pipelines (MР) with a long service life (40 years or more), the reliability of operation is ensured by compliance with regulatory requirements. Calculations of the stress-strain state of gas pipelines, in particular, longitudinal stresses, are carried out in accordance with Standart SP 36.13330.2012 «Main pipelines», which does not take into account the life of the facilities. The analysis of SP 36.13330.2012 «Main pipelines» for the effect of the temperature factor on the magnitude of the longitudinal stresses of the gas pipeline section showed that the calculation of longitudinal stresses from the temperature difference ∆Т provides for taking into account four values: Тс – maximum and minimum temperatures during construction; Tр – the highest and lowest temperatures during operation. When considering the stages of construction of gas pipelines, it was established that during this period the pipeline experiences the action of four temperature regimes, and when put into operation, the fifth complex one: from the temperature and pressure of the gas, at which the consolidation of the main pipeline with the surrounding soil occurs predominantly in during which the linear-altitude position of the MР section with a minimum of stresses is predominantly formed. It has been proved that, in relation to the calculations of longitudinal stresses of gas pipelines with a long service life, it is necessary and sufficient to limit the calculated temperature difference by Tр. SP 36.13330.2012 is intended for calculations during the construction of new pipelines, and its use for long-term operated gas pipelines, taking into account the standard value of ∆Т, mainly leads to rejection, and, therefore, to repair. We believe that for the operation of MР with a long service life, for the calculation of thermal stresses, it is necessary to develop a standard that allows the calculation of the temperature difference ∆Т by the value of the operating temperature Tр.