Effect of Soil Physical Properties on the Corrosion of underground API 5lx70 Steel Pipeline along Kaduna-Kano, Nigeria

Abstract

This study was conducted along a 130km transect to assess the impact of some soil physical properties on buried API 5L X70 steel pipeline conveying petroleum products from Kaduna to Kano. Nine (9) soil samples were collected at an interval of 14.6km at a not less than one-meter depth. Laboratory analyses were carried out using pH for soil acidity or otherwise, the Gravimetric drying method using Weight differences for soil moisture and Bouyoucos method for soil texture determination. The results along the transect showed a pH range of 4.1 – 8.2, a moisture range of between 20 – 40%, and clay contents between 1- 10%. An API 5L X70 steel pipeline coupon of 60x40x10mm was then buried for 120 days in each sample to determine corrosion rates. Based on the results, corresponding corrosion rates were obtained to be between 0.0043 – 0.05mg/dm²/yr along the transect, signifying a relative increase in corrosion along the 130km pipeline, implying relatively varied corrosion rates occurrence with all the three parameters been positive and impactful the pipeline’s corrosivity.