rigid plastic pipes for conveying natural gas; rigid plastic pipes for plumbing purposes; rigid pipes of polypropylene for building; plastic water pipes; rigid plastic pipes for conveying water; rigid pipes of polyethylene for building; rigid plastic pipes for conveying storm water; rigid plastic pipes for conveying oil; rigid plastic pipes for conveying gas; non-metal drain pipes; rigid underdrainage pipes, not of metal; rigid plastic pipes for liquid and gas transfer; plastic storm sewer pi...