Smart superconducting grid is a global network for CO2 emissions-free renewable energy economy. The grid combines delivery of liquid hydrogen and electrical energy via superconducting pipelines. The paper reviews the development of the grid concept and the efforts in material science and engineering advancing its practical implementation. Original results are presented outlining an activity that targets the challenge of joining sections of pipelines, as well as manufacture of superconducting pipes. The focus is put on testing the quality of superconducting MgB2 joints and coatings using the magnetic flux visualization technique of magneto-optical imaging.