PE-RT has emerged.

by 9aincemiss on 2012-02-13 19:15:04

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PE-RT has drawn attention due to its excellent stability, long-term pressure resistance, ease of bending during installation, good impact resistance, safety, resistance to aging, long service life, convenient processing technology, quality control, and recyclability. As PE-RT becomes increasingly familiar to people, the dominance of PEX pipes in the underfloor heating market is gradually being broken. Currently, PE-RT pipes have become one of the mainstream products in the underfloor heating market alongside PEX pipes.

The rapid development of PE-RT pipes has achieved technical upgrades. With the growing number of underfloor heating consumers moving southward year by year, PE-RT pipes have entered their golden age of development. China has now become the largest global market for PE-RT, and PE-RT has also been updated and upgraded, becoming one of the fastest-growing pipe materials in recent years.

Why can PE-RT develop so quickly? This is because it has certain advantages. Ordinary PE pipes can only be used for cold water below 40°C, while PE-RT pipes can be used for both cold and hot water transport. In the 1990s, Dow Chemical first successfully developed PE-RT, followed by SK and LG companies which also developed their own grades. These all belong to the first generation of PE-RT materials, abbreviated as PE-RTI. With the continuous development of PE synthesis technology, starting from 2000, Dow Chemical, Basell, and some Korean companies successively launched the second generation of PE-RT, abbreviated as PE-RTII. Compared to PE-RTI, PE-RTII has higher strength at high temperatures, better creep resistance, allowing for thinner walls in applications, thus saving raw materials, reducing costs, and increasing the diameter.

PE-RTII shows obvious advantages at high temperatures. However, this advantage of PE-RTII is clearly evident only in high-temperature hot water environments. This can be seen in the size selection between PE-RTI and PE-RTII.

The situation where PEX pipes dominated the underfloor heating market is gradually being broken. The size selection of PE-RT pipes depends on the conditions of the usage environment. Under different usage conditions, the S value series of pipes, which serves as the basis for design and use, varies. The S value is related to the pipe dimensions. Pipes with the same S value have identical dimensions. Once the S value of the pipe is selected, the pipe size is determined. However, pipes with different S values will have different wall thicknesses. For example, PPR φ20 pipes used in cold water systems often select S5 and S4 series, with wall thicknesses of 2.0 mm and 2.3 mm respectively; when used in hot water systems, they generally select S3.2 and S2.5 series, with wall thicknesses of 2.8 mm and 3.4 mm respectively.

So, how are the sizes of PE-RTI and PE-RTII pipes selected in underfloor heating systems? ISO22391-2009, German standard DIN16833-2009, and the new national standard draft (Ministry of Construction Standard CJ/T175-2002) specify relevant regulations. According to the data provided by these standards, we can see that the series numbers of pipes selected under the same design application pressure for PE-RTI and PE-RTII are exactly the same, meaning the dimensions are completely identical.

Why is this so? The main reason is that the advantage of PE-RTII in high-temperature hot water environments is more pronounced, but in low-temperature underfloor heating systems, the improvement in strength of PE-RTII compared to PE-RTI at low temperatures is not significant enough to reduce wall thickness, save raw materials, or increase the diameter. In high-temperature environments, this characteristic of PE-RTII would be clearly evident.

Currently, the cold and hot water pipe market is mainly dominated by PPR pipes. Can PE-RT further expand its influence and dominate the cold and hot water market with its current high-temperature resistant advantage? We need to wait and see.