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Butt or overlap PEX-AL-PEX pipeline? Which one is better?

Author: Hits:351 Date:2020-09-27



ALPEX pipes are widely used in cold&hot water system and heating radiator fields due to its features of light weight, high strength and temperature resistance, convenient installation and 100% isolated gas permeation etc.


This multi-layer composite PEX-AL-PEX pipe can be produced by:

l Ultrasonic overlap welding

l Argon arc butting welding method.

Butt or overlap PEX-AL-PEX pipeline, which one will be the better choice?

After all, the price is different, investors are bound to have a question at the begining of their investment: Butt or overlap PEX-AL-PEX pipeline, which one will be the better choice?


The overlap type’s welding space is big, then the aluminum strip is thinner, while for butt welding, the aluminum needs to be thicker since you need to ensure the welding space is enough. Then, men are commonly believed that butt welding is more suitable for high temperature and high pressure suitations because of the thicker Aluminum strip.


However, through the calculating of long-term hydrostatic pressure strength(P0 )of these two pipes, it’s proved that the overlap welding type can fit the requirement of 1.25MPA, 95° with 50 years. That means the overlap welding pipe will be no side crack and no leakage under 1.25MPA, 95° with 50 years.


Here’s the long-term hydrostatic strength testing result (according to national standard for Min thickness and Min tensile strength of Al layer for butt welding and overlap welding);

l It shows 2 kinds of pipe P0 value is same when small diameter.

l Only when bigger diameter, the butt welding type have an obviously advantages.

Welding mode

Pipe diameter

Aluminum thickness

P0(MPa)

Ultrasonic overlapped welding mode

16

0.18

2.57

20

0.23

2.58

25

0.23

2.05

32

0.28

1.94

40

0.33

1.84

50

0.47

2.12

Agron arc butt welding method

16

0.24

2.85

20

0.32

2.96

25

0.40

2.94

32

0.56

3.11

40

0.71

3.13

50

0.96

3.36


As a manufacturer of ALPEX pipe making machine with 20+ years experience, we,weifang kaide plastics machinery Co.,Ltd, produce both of the 2 machineries.



After years of the experience, we notice that:

l customers are mainly using ALPEX/ALPERT 16-32mm pipes for buildings cold&hot water system, and radiator heating system.

l And we can obviously feel that the customers are preferring ultrasonic overlapped welding PEX-AL-PEX/PERT-AL-PERT/PPR-AL-PPR pipe machine more.

l Take Chinese market for example, overlap welded Al-plastic pipes machine have occupied the mainstream position after more than two decades of survival of the fittest.

l The overlap pipe’s using history of high-temperature radiators in the China northern regions has been more than 25 years, and it’s still running well till now.

l Many years of project practical experience also proved that overlap welded aluminum-plastic pipes can also be used in high temperature and pressure situations.




But, argon arc welding pipes have not become active on the market due to high cost of the aluminum strip used, relatively complex processing technology, the higher requirements for the operating experience of the workers, and the high equipment investment cost etc.