Steam Pipe Fiberglass Insulation versus Asbestos air cell insulation

Roma

Good day.  I am redoing my basement and my steam heat pipes are exposed.  Some of the asbestos aircell insulation is gone.  I would like to replace it with a safer fiberglass pipe insulation.  I have been trying to find out the r value of the existing asbestos aircell pipe wrap material (with no luck).  I am trying to see what thickness fiberglass pipe insulation I should put back in place of the asbestos.  Also, do I need to insulate the returns as well.