This article concentrates and examines on how to calculate the changes in pressure, temperature, and the velocity of Gas due to the changes in elevation. The radius of the gas transfer pipelines is calculated and the results of the studies from the simulation software of ASPEN- HYSYS (GAS-PIPE), and eventually it will compare with the actual condition on the ground.
The simulation takes place in three methods. In the first method a model made from a segment of third transfer pipeline in distance of Rasht-Qazvin in which the changes of elevation is considered as zero, in the second method, the same model is put in use with condition of changes in elevation, and in the third method the profile of the elevations changes is the main consideration.
Next, is to use the simulation software; the GASPIPE take place in model making. Then the results of all three models are compared. The main goal of this model making is to indicate the important role of elevation in pressure change, velocity, the temperature and assessment of operation and the usage of gas in the populated area of negative changes in elevation. The result of these studies can help to make improvement in circle of gas transportation, expenses and consumption, prompt usage of facilities in improving gas pressure, reduction of gas consumption, condition calculation and determination of pressure in changes of elevation changes.