Study on corrosion control of natural gas distribution pipeline at Munshiganj

Abstract

In Bangladesh, pipe line quality natural gas is the principal source of energy. To ensure proper distribution of it to the end users 16.459 thousand kilometer steel pipe line« have been constructOOSOfar. The market share ofTitas Gas Transmission and Distribution Company Limllcd (TGTDCL) on the basis of pipe line corumuction among four companies in ~le counlIy is Ule highcst and about 8.70 thousand kilometers. As these pipelines are growing old, it 1$ becoming more difficult to protect them from the damage eaused by wITOsion. Mushig1l.njtown, a distribution network of TOTDCL is the present area of interest, as severe corrosion took place in some ponlOn of pipelines of this area in 1999. An evahtation of existing corrosion control sy~tem of the said area has been made. Stndy shows exi~ting 30 Amp. x 20 volt TR wlit based impressed current system of cathodic pmtection is not adequate to protect all the pipe lines in the area from corrosion. On the oU)erhand impressed CUITeutsystem of cathodic protection )s not fully appropriate for the area. Logarithmic mean resistivity of the pipe line environment is 2455 ohm-cm. Most of the pipelines are distributed in two part of thc town, one part is called Munshiganj and another pan is called Mirkadim. Both of these regions are often [loaded by the surge of two adjacent rivers and most of the lines are smaller thall3 iueh in diamcter. Sacrificial anode method has been suggested as unproved design for these areas, The other portion consists of 6 inch to 12 mch diameter distribution mains. This part is 12 Ian long and laid along highway. For this segment impressed current system has been suggested as improved desigll. For implementmg the improved desil-;n,Tk. 53.21 Lac is required to invest. Financial analysis shows that the investment is vlable as compared to the increased operating cost for progressively worn out pipe lines and cost of unaccounted for gas (UFO) for enhanced corrosion in the Ilext 20 years.