DEVELOPMENT OF API 5L X-80 PLATES & PIPES AT ESSAR STEEL

India is a large and rapidly growing economy. The energy requirements of the country in terms of oil products and natural gas is also huge. Given its vast geographical size, there is ever-growing need to transport these oil & gas products over large distances but economically For this purpose, several new projects for laying of new pipe-line networks are at different stages of planning. In order to keep the cost of such large pipeline projects lower; countries around the world have shifted to higher strength API grades of steel. This was facilitated by advances in steel-making and processing technology and modern facilities that came up in advanced countries. India is no different and we have seen a gradual shift towards higher strength API grades being used for pipelines. Essar Steel has been a major producer of API grades of steel in India over the last 15 years initially through its hot-strip mill and more recently adding a state-of-the-art 5M wide plate mill as well as pipe mills, both LSAW & HSAW. Different alloy designs have been used around the world to produce high strength and high toughness API grades. These have produced essentially two types of microstructures which are either ferrite + pearlite or ferrite + acicular ferrite. But these microstructures show varying response to the pipe-making process. Choice of alloy design also has a major bearing on the cost of steel, but is partly influenced by mill capability. At Essar; while cost was a major determining criterion for selection of suitable alloy design, mill capability was not a constraint. Essar Steel has successfully produced X-80 plates and pipes with a modified HTP alloy design and using the new facilities of plate mill & pipe mill. The paper gives some of the key highlights of this development activity. This was a collaborative effort between the metallurgists & engineers at Essar Steel India Limited and experts from CBM-M.