The weldability and mechanical properties of welded joints of pipeline steels of grades API 5L (X52, X60, X65 and X70) manufactured by submerged arc welding (SAW) are investigated. It is shown that the SAW process makes it possible to obtain high-quality welded joints. It is shown that such welded joints fracture during tensile tests over the base metal region. The weld region has the highest hardness and ultimate tensile strength, which are 214 HV10 and 713 MPa for steels X70 and X65 respectively. These values are higher than that of the base metal.