Calculated definition of heating duration of the polypropylene pipes for transportation at low temperatures

Abstract
Loading and unloading of polypropylene pipes and their transportation should be carried out at ambient temperature not below –10 оC according to standard documents. For transportation of the polypropylene pipes at ambient temperatures below standard ones it is proposed to keep them in not heated rooms putting in the heat-insulating containers, where heating of pipes is carried out by heated air supply. At the assumptions not limiting the practical use, the mathematical model describing dynamics of a temperature field in the heat-isolated pipe while heating by heated air and cooling during loading, transportation and unloading is offered. Calculation results of temperature change are given for external surfaces of the polypropylene pipes for hot water supply having different sizes with thermal insulation during heating by heated air to 80 оC at ambient temperature of –40 оC to determine heating duration up to a given temperature of pipe wall. Calculations showed that the polypropylene pipes of hot water supply, which are heated to 20 оC, can be transported at low temperatures on sufficiently long distances. On the basis of calculation methods for duration of heating and cooling to a given temperature for polypropylene pipes with thermal insulation the method of calculation of heating duration necessary for loading, transportation and unloading at the given expenses of their implementation time is offered. The calculations made allowed to conclude that the proposed method of transportation with heating in heat-insulating containers can be used for transportation of the polypropylene pipes at the ambient temperatures below standard over considerable distances within a settlement.