In conventional copper, steel, or other rigid hot or cold water pipes the piping is rigid and self-supporting such that foam PE, rubber, or fiberglass pipe insulation of tubular construction with ⅜ to 1 inch wall thickness is slit and installed over the piping to prevent heat or cooling loss to the environment and thus save energy.  In the case of cold water, this insulation also prevents condensate from forming on the pipe and dripping onto surrounding surfaces.  This dripping can create moisture damage or mold over long time spans.  Also, for very cold unheated areas, insulated pipes can prevent freezing and bursting of pipes. 
With the recent increasing use of plastic tubing and more recently PEX (crosslinked polyethylene) tubing for hydronic heating and cooling as well as for supplying hot and cold water for domestic use and other applications, the insulation of this tubing is difficult because the tubing is flexible and also because it expands and becomes more flexible as its temperature increases.  Typically the tubing, usually ½ to 1 inch outside diameter, is supported with hangers spaced every 1 to 3 feet to prevent excessive sagging.  These hangers have a small width of about ½ of an inch to about an inch. 
A typical tube of ½ inch outside diameter will be supported with a hanger attached to the floor joist or other structural member every 18 inches and will sag about ¼ or ½ of an inch when transporting with hot fluid.  Also, multiple tubes, sometimes up to 6 or more, are mounted close together such that there is not enough space between them to install tubular pipe insulation. 
Plastic pipes for plumbing and hydronic heating are increasing in market share for residential and commercial use as copper prices increase significantly and flexible plastic piping is becoming easier to install and more reliable.  Types of plastic piping used for plumbing are primarily PEX (crosslinked polyethylene) and CPVC (chlorinated PVC).  PEX is gaining market share due to its ease of installation and high reliability for fittings and connectors.  Also, the flexibility of PEX makes it easy and fast to install.  PEX is finding wider use both for hot and cold water and for hot water heating applications both in the US and in Europe.  Typical plastic piping sizes for PEX vary from ½ inch to 1¼ inch diameters. 
Studies have shown that heat loss from hot water pipes can be substantially reduced by adding polymer foam or fiberglass insulation around the pipes.  Typical insulation wall thickness for this insulation is ⅜ to ¾ inch wall thickness.  Surprisingly, it has been shown that heat loss (BTU/h/ft) for bare ¾ inch PEX domestic hot water (DHW) piping is greater than for copper piping (31.96 vs 29.64 BTU/h/ft) at 140° F. This is due to higher radiant and convective losses for the PEX versus copper, even though the thermal conductivity of copper is substantially higher than PEX. 
It has been shown that by adding ½ inch wall thickness flexible elastomeric insulation to both the copper and the PEX, the heat loss is reduced by 65% for the copper (from 29.64 to 10.3 BTU/h/ft) and 69% for the PEX (from 31.96 to 10.06 BTU/h/ft).  The problem with insulating flexible PEX or CPVC pipe is that, different from rigid copper or iron pipe, since the plastic is flexible, it must be supported every 18 to 24 inches for smaller (approx.  ½ inch diameter) and every 36 to 48 inches for larger (approx.  ¾ to 1 inch diameter) pipe due to its flexibility and tendency to sag.  For uninsulated plastic piping this is usually accomplished with a small-width hanger that mounts the piping either in direct contact or nearly in contact (about ⅛ inch) with the supporting structure.  This mount does not leave room for insulating material, either polymeric foam or fiberglass, of approximately ½ inch or more wall thickness between the pipe and the support structure, such as a floor joist or wall stud. 
Pipe hangers have been developed which can allow room for the foam insulation.  However, they are large and bulky and quite expensive and require extra labor.  Some such hangers connect over the insulated PEX pipe while others provide an insulation for the pipe and require additional insulation to be installed in short spaces between the mounts.  This can leave gaps in the insulation and requires additional labor and is not very compact when there are multiple pipes in close proximity.  Also, this system will not work where hydronic pipes require multiple pipes in small spaces. 
As such, a need exists for improved support systems and apparatuses for pipes that can insulate the pipes over a substantial length of the pipes.