polyproplene pipes used for hot water supply under ground should be insulated or not but i need justification

Answer 1

*Based on the polymerization conditions and the incorporation of the ethylene copolymer, polypropylenes can be differentiated in PP Homopolymer (PP-H), PP Random copolymer (PP-R) and PP Block copolymer (PP-B).

The property profiles of the different types of polypropylene also make them suitable for different types of application: PP-H is normally used in industrial pressure pipe systems and for soil and waste water pipes and fittings, based mainly on its good mechanical properties and excellent chemical resistance. PP-R is a well proven material in domestic pressure piping systems for hot and cold water due to its high internal pressure resistance and long lifetime at elevated temperatures.

For buried sewerage and drainage applications, waste water systems and ducting pipe systems, PP-B is the obvious choice. This is mainly due to its high stiffness, high impact strength, especially at low temperatures, good long term properties and excellent chemical resistance.

Based on these properties, PP-B is commonly used also for other non pressure systems, in particular for soil and waste water piping systems and for cable protection systems.

*PP Pipe systems are replacing traditional copper, clay and concrete pipes in hot and cold water distribution, as well as sewage and drainage applications.

Typical applications for polypropylene:

In House
Waste Water
Hot & cold water
Floor and wall heating
Cable conduits

High temperature resistance, 60°C – short term up to 90°C.
*In our area expansion joints are required in trenches. The summer temp of that earth we can say 55 degrees but that is not really accurate due to sun warming earth over all summer to a certain depth. But lets stick with the 55 degrees for simplicity. Now if you check the IRC for Indiana our frost depth reaches 30" almost double the minimum burial depth of 18" required for PVC. Our temperature this week and last week has driven frozen ground 24" deep in most places in this area. This makes a differential of temperature change to equal to freezing at 32 degrees and 55 degrees in summer of 23 degrees. This would suggest approximately 2" of expansion or retraction for a 200 foot run in that temperature range of 25 degrees change. If you put the conduit in during the hot summer at 55 degrees and the frost hits below your conduit for a 200' run. When we go from warm to cold in that temp range that conduit is predicted to shorten in frozen ground about 2" pulling that conduit apart in the trench. I know it does not seem like much but try to remember back posts asking why there is always water in PVC underground and why after they installed PVC underground they could seldom pull the wires out or pull new ones in. There are many areas in the US that frost line well exceed the 30" depth found in Indiana. Just thought I would post some words for thought. I know many have said much like you have about earth not changing temp much but that is locations below frost level. Remember if frost reaches 30" in Indiana then heat when the conduit was installed was warmer than 55 degrees and locations below frost line will lower to a depth below that frost line just not below freezing. I believe in Northern Minnisota frost level by memory if 50".

*USE U-PVC.No need to insulate.

Answer 2

There's no easy answer to this, because it does depend on 1) the size of the pipe 2) the run 3) the application. Underground temperatures relatively near the surface (as expected in normal construction) rarely exceeds 80 degrees Fahrenheit, and hot water supply temperatures tend to be at least 140 degrees. For long runs with small piping, you can expect the water to cool to ground temperatures, so most of the time this is not a wanted outcome. There are standard insulating wraps for this sort of problem. Polypropylene itself is a fairly good insulator, but most propropylene pipes aren't thick enough to provide adequate insulation in a case like this. Remember, heat conducts through ground much more efficiently than through air.

Answer 3

no they dont need to be insulated because they are far enough underground that the temperature above ground doesnt affect them

4ft. is the normal frost line for ground so as long as they are below that the ground stays at a constant temp. usually around 50 degrees or so

B.

Answer 4

Depends on where you live. If you live in a place where the frost line does not extend to the level that the pipes will be at you are fine.

If your frost level is lower than the level of your pipes then you will need to insulate.

Answer 5

Need more information...

How far is the pipe going to be routed underground? (in feet)
How deep will the pipe be buried?
What is the temperature of the hot water?
Pipe size and approx. flow rates? (Min = 0 gpm, Max = ? gpm)

If you insulate it, use a rigid foam type insulation, lagged with a hard poly cover.

Answer 6

it should be insulated , so that the heat does not escape to heat the ground.