How to weld PPR pipe to ensure the quality of PP-R pipe welding

How to ensure the quality of PP-R pipe welding? To select a qualified hot melt welder, the temperature control of the hot melt welder should be correct and the thermostatic time should be long. To select a qualified and suitable weld sleeve, the qualified weld sleeve is designed with full consideration of the cross-sectional structure and weld depth of the welded tube, as well as surface non-stick and surface finish. The following small series will introduce you in detail to the methods and steps to ensure the quality of PP-R pipe welding.

First, we must choose a qualified hot melt welder.

The temperature control is correct. The PP-R hot melt welding temperature is: 253 ° C - 274 ° C. If the temperature is lower than 253 ° C, the tube and the tube are only a layer of thin surface melting, once they are welded, the strength of the fusion is not guaranteed, which is what we usually call the false welding phenomenon; If the temperature is higher than 274 ° C, the surface molecules of the tubes and tubes are destroyed by high temperature, so that PP-R forms a thin liquid, which will make the inner diameter of the tube smaller, and more importantly, the joint portion will be brittle. Especially when the pipeline system is completely completed, the water is pressurized, and such problems often occur.

The constant temperature time is long. The length of the constant temperature is one of the important signs of the performance of the hot melt welding equipment. The hot melt equipment still has a problem of heat consumption after heating up to the set temperature, especially in the winter, at the tuyere, even in the non-working gap, the heat consumption is very large, and once the operation, the pipe and the pipe fittings They are all consuming heat energy separately, which requires the equipment to have a strong thermal energy storage capacity and timely replenishment capability.

How to weld PPR pipe to ensure the quality of PP-R pipe welding

Second, you must choose a qualified and suitable welding sleeve.

Qualified welding sleeves are designed with full consideration of the cross-sectional structure and weld depth of the welded tube, as well as surface non-stick and surface finish. At present, there are hundreds of domestically produced manufacturers of water pipes for welding PP-R, PPC, PE, etc. by means of hot melt. Due to the raw materials used in the pipes produced by various manufacturers, different auxiliaries, different environmental conditions, and different equipment choices, the sizes of pipes and fittings produced by each manufacturer are also different. Therefore, each pipe manufacturer and user must choose a welding sleeve suitable for their own pipe diameter. For the operator, the surface of the welding sleeve should be cleaned after the last welding to avoid impurities in the welded part.

When welding a pipe with a diameter of 40 mm or more, due to the large diameter, non-personal force can work, mechanical equipment must be used to ensure the depth and straightness of the pipe into the pipe. We found that on a number of construction sites, five to six workers were used to weld a 110 mm diameter interface. The force of the tube could not guarantee the straightness and insertion depth of the tube. The entire pipeline was curved and it was difficult to imagine a certain water temperature. And the situation under pressure.

Third, problems that are prone to occur in hot melt welding.

It should be said that the pipeline system that is strictly in accordance with the requirements of the welding process and the welding technology is not used at normal temperature and pressure. However, in daily construction, we often find that there is a burst or blister at the joint between the pipe and the pipe.

The main reasons are as follows:

The temperature of the hot-melt welder is incorrect, too high or too low, so that the performance of the polypropylene changes;

The surface of the welding sleeve is not treated well, or the surface coating is peeled off to cause blisters in contact with the tube;

The size of the welding sleeve is incorrect and the design is incorrect, which makes the melting depth and welding structure of the pipe inappropriate.

The welding surface of the pipe is not cleaned before welding;

The welded pipe and the pipe are not kept concentric or straight.

Fourth, the correct welding procedures.

Preparation before hot melt welding

For tubes with an outer diameter of 25-110 mm, the chamfering device shall chamfer the pipe port by 15° to half the original pipe wall thickness;

Clean the surface of the welded part of the pipe with a cleaning machine (or alcohol) and a brush;

When the pre-assembled parts are welded, the markings are made at the required locations for the tubes and fittings prior to joining.

For pipe welding above 40mm diameter, flat and vertical pipe welding machines must be used;

After each dissolution, wipe the heating sleeve and the heating head with a dry cloth or dry paper. Do not use detergent.

Hot melt and connection

After inserting the tube and fitting into the heating jacket and the heating head, do not rotate or move too fast (to allow the material to melt enough).

After heating, remove the tube and fitting from the heating element and do not rotate the heated part.

Immediately after heating, press the tube and the tube together along the axis, and do not rotate. Strictly observe the retention time and cooling time of the hot melt welding standard.

Grooved Pipe Couplings

Groove Couplings are generally composed of sealing rubber ring, clamp and lock bolt three parts. Because of its unique rubber seal ring and clamp structure design can be made, so that the grooved connector has a good seal, and with the fluid pressure within the pipe increases, its sealing increased accordingly.

Material: Ductile Iron Casting, conforming to ASTM A536 65-45-12 Equal to QT450-12.

Seal: NBR, EPDM

Bolts & Nuts: Q235A

Coating: 1.Painting 2.Epoxy 3.Dacromet 4.Galvanized

Colour: 1.Red 2.Blue 3.White 4.Orange

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HEBEI ZIFENG NEW ENERGY TECHNOLOGY CO.,LTD. , https://www.zifengpipeline.com