When it is impractical to test 100% of the days girth welds made on a liquid transportation pipeline for hazardous substances, no less than ___ shall be non destructively tested if the pipe is run within a railroads right of way

When it is impractical to test 100% of the days girth welds made on a liquid transportation pipeline for hazardous substances, no less than ___ shall be non destructively tested if the pipe is run within a railroads right of way