Welding of 80 Kg/MM2 H. E. T. Welten-80 Steel for Kalinadi Project

The first indigenously fabricated penstock was erected for the Madras State Electricity Board during the year 1939. Thereafter a number of schemes have been completed by using M.S. and High Tensile Steels for the fabrication of penstock pipes. It was in the year 1965 that Tt -A steel, which is an Extra High Tensile Steel, was used for the first time in the country for the Sharavathi Hydel Project in Karnataka. The reason for using this steel was economic advantage over the conventional type of steel. The total tonnage used was about 20,000. Upper Silleru was the next project to use this steel in 1966 and about 524 tonnes were used for fabrication. The third project to use T-l steel was the Beas-Sutlej Link Project.

The present paper deals with the Extra High Tensile Steel (Welten-80) 80 Kg/mm², used for the fabrication of penstock pipes for the Kalinadi Project in Karnataka State. The paper deals with the physical and chemical properties of the material, welding technique, preheat, interpass and post heat treatment, preservation of electrodes, etc. The paper also deals with the problems in welding this type of steel, both at the factory and at the site of erection. The discussion reviews the developments within the guidelines of relevant codes and standards, with a view to meet the developments of future requirements.