How to properly solder polypropylene pipes

2024 Author: Malcolm Clapton | [email protected]. Last modified: 2023-12-17 03:44

The parts heat up to 260 ° C and bond so tightly that the joint is stronger than the pipe itself.

1. Prepare materials and tools

• Pipes;
• fitting;
• napkins;
• gloves;
• soldering iron;
• pipe scissors;
• roulette;
• pencil;
• level;
• isopropyl alcohol.

2. Make a piping diagram

The connection of polypropylene pipes is quite simple, but - as with any other structure - it is advisable to prepare an approximate installation scheme before starting work.

Sketch on paper a drawing with the location of the tie-in points, valves and other necessary parts. So you can immediately estimate the length of the pipes, as well as determine the location, type and number of fittings required.

Since the connection heats up both ends of the pipeline, it is important for ease of installation that one of them remains free. Some of the pipes with fittings can be assembled on the table, and then installed in the desired place, making just one joint. All this will help to provide an assembly diagram.

3. Prepare the soldering iron

In general, the device is correctly called "welding machine". The process of joining polypropylene takes place without the use of solder, which means it is welding, not soldering. We will use both terms.

Install nozzles of the required diameter on the platform of the soldering iron and fix them with a screw using a wrench. If you are working with pipes of several sizes - use an additional pair of sleeves.

Set the heating temperature to 260 ° C and plug in the device. It will take 10–20 minutes to heat up. The readiness for operation will be indicated by the LED indicator. You need to wait another 5 minutes before welding the first joint.

When polypropylene is heated, harmful vapors and smoke are emitted, which it is better not to inhale. Therefore, ventilate the room during operation.

4. Make the markup

While the soldering iron is heating, prepare the pipe and fittings. For high-quality welding, they must enter each other strictly to a certain depth. Insufficient immersion will result in a poor connection, and excessive immersion will reduce or completely block the flow area with the extruded plastic. Here are the values recommended by most manufacturers for the most common sizes:

As you can see, the soldering depth depends on the diameter of the pipes and fittings.

In order not to be mistaken, measure the required length of the pipe, taking into account the seam allowance and draw a line with a pencil. Then, at the desired distance from this mark, draw another line - it will serve as a reference point during welding.

For example, we need to connect a corner and a tee in the heating system. The distance between them is 270 mm. For fittings with a diameter of 25 mm, the soldering depth is 18 mm, which means we add another 36 mm to 270 (18 on each side). As a result, it turns out 306 mm - just such a piece of pipe should be cut off.

5. Cut the pipe

For cutting polypropylene, special scissors are used, which are also called a pipe cutter. They allow you to easily cut off thick-walled pipe and get smooth, burr-free edges.

Set the scissors exactly perpendicular to the pipe and align the blade with the first mark. While holding the pipe with one hand, press the scissor handles with the other until the part is completely cut.

It is important to get a flat end so that the pipe evenly enters the fitting and is equally soldered along the entire diameter. If cut obliquely, the protruding part will go too deep and the molten polypropylene will be squeezed out, reducing the inner diameter of the fitting.

If the edge is uneven and allows for a margin, it is better to cut it off again. If the length is end-to-end, trim the butt by removing all excess with a sharp knife.

6. Degrease the parts

According to the instructions of all manufacturers, the parts to be welded must be degreased for a good connection. And although many craftsmen neglect this and limit themselves only to wiping the pipes with a rag, we recommend adhering to the technology.

Clean any contamination from the pipes. Drain off any remaining water and dry thoroughly with a tissue or toilet paper. Clean the surfaces of fittings and pipes with a cloth dampened with isopropyl alcohol.

With the same alcohol, it is easy to erase all the inscriptions on the pipes and give them a more aesthetic look.

7. Heat pipe and fitting

There is a risk of serious burns when working with a hot soldering iron, so be sure to wear protective gloves. Parts of various sizes need to be heated for a certain period of time. The larger the diameter, the longer.

For a reliable connection, it is important not to overheat polypropylene, otherwise the material will become fluid, melt and block the fitting from the inside.

Insert the fitting first, then the pipe into the corresponding sleeves of the soldering iron. When pushing the parts, do not rotate them around their axis or tilt them. Insert the pipe to the previously marked depth, until the molten polypropylene reaches the pencil line. Only then count the allotted time.

All indicated data are valid for work at an ambient temperature of about 20 ° C. If the room is colder than 5 ° C, then the heating time is approximately doubled.

8. Weld the joint

Without turning or tilting, quickly remove the pipe from the nozzles, and then the fitting, and connect both parts in the desired position relative to each other. Don't fuss, but don't hesitate - you have 4-6 seconds left.

Hold the pipe and fitting still for about 5 seconds to secure the joint. At this point, it is allowed to rotate the connection no more than 10 degrees to correct its position.

The total cooling time, after which the weld can be loaded, is 2 to 4 minutes.

It is easy to remove the remaining polypropylene from the nozzle with a paper towel while the soldering iron is hot. If you clean the already cooled sleeves, there is a risk of damaging the Teflon coating.

9. Check the connection

You can determine the quality of the weld by a small uniform bead at the end of the fitting. If it is not there, then, perhaps, the joint is underheated and the tightness will be questionable. If the influx is too large, the pipe is most likely overheated, and it melted inside, partially and completely blocking the flow area.

For those who are dealing with polypropylene welding for the first time, it will not be superfluous to first practice and weld several training joints. It is better to learn on straight couplings. Unlike corners and other complex-shaped fittings, they are easy to inspect well after soldering, not only from the outside, but also from the inside.