Which type of plumbing pipe requires specific hanger spacing due to its flexibility?

CPVC pipe, or Chlorinated Polyvinyl Chloride pipe, requires particular hanger spacing because of its flexibility. This type of pipe can expand and contract with temperature changes, which affects its structural integrity and can lead to sagging or other potential issues if not properly supported.

The Massachusetts Plumbing Code specifies the required spacing for hangers to ensure CPVC pipes are adequately supported and to maintain the system's functionality and safety over time. Proper hanger spacing prevents excessive movement, which can result in stress on joints and may lead to leaks or breaks in the pipe.

In contrast, other types of pipes like metal, cast iron, and PVC have different physical characteristics, which dictate their own specific requirements for hanger spacing. For instance, metal pipes are generally more rigid and thus have different support needs compared to flexible materials like CPVC.