Will HDPE pipes filled with water burst in the cold? Definitely not! But there is one caveat

Many argue that HDPE pipes can withstand low temperatures. But my neighbor has a fence irrigation system laid. In the fall, everything is drained and blown out so that the pipes do not burst in winter. And all the same - water is collected, and in the spring the result is found - two or three burst places. Hanging trolley repair couplings.
So after all, will HDPE pipes be able to withstand frost? If not, why not?

What is HDPE?

HDPE- these are letters that say that pipes are made of low-pressure polyethylene (0.941-0.965), i.e. high density polyethylene.
HDPE is a good material. It is very sturdy, durable and reliable. To scratch it, you need to use a sharp object, while making an effort.
The material is sturdy. Manufacturers claim to withstand low temperatures. But how are HDPE pipes actually doing with the cold?

A bit of physics ...

Winter is frost, i.e. negative air temperature. HDPE pipes are usually filled with liquid. And what happens to the liquid in the cold? She freezes. When it freezes, the density of the liquid changes and it expands. It is because of this expansion that any pipes that do not have sufficient elasticity will burst.

High-quality HDPE pipes have this elasticity. They do withstand sub-zero temperatures and endure several freeze and thaw cycles.

BUT! There is always a BUT. A pipeline is not just pipes. They are also connecting elements. And it is with them that problems most often arise.

Often people do not think about the quality of the connecting parts, but they should do it. They must be made from frost-resistant materials. Otherwise, no plumbing will be able to survive the winter without consequences.

HDPE will withstand a cold snap. If the water in the HDPE pipe freezes, due to its properties, the pipe will simply stretch a little. And with warming, the icy water will melt, and the pipe will return to its former shape. But unsuitable connections do not withstand and burst.

But even despite the frost resistance and some elasticity of HDPE pipes, it is still recommended to lay them in the ground below the freezing level. For more peace and one thing, add electrodes or fire tools to them.

But even despite the frost, if the water in the HDPE pipe freezes, due to its properties the pipe will simply stretch a little. And with warming, the icy water will melt, and the pipe will return to its former shape. But unsuitable connections do not withstand and burst. But even despite the frost resistance and some elasticity of HDPE pipes, it is still recommended to lay them in the ground below the freezing level. For more peace and one thing, add electrodes or fire tools to them.

So the answer to the question: does HDPE pipes break in the cold? No, it doesn't break pipes! But the hardware at low temperatures can very quickly fly out of order..

So choose not only high-quality pipes, but also high-quality connecting elements made of frost-resistant materials.