Pipeline welding method and the necessity of quality inspection

The pe pipe is a kind of material made of polyethylene. It not only has special processing methods, but also the pe pipe welding method is also more complicated, and there are many matters needing attention. However, it can be seen that the use of the PE pipe at our side is relatively large, and it has indeed played a large role in many areas. Therefore, we must take a good grasp of PE pipe welding technology. If you are interested in this, you may wish to follow me to learn about it!

The basic method of PE pipe welding

The common common PE pipe welding method uses a hot melt butt welding method. In this method, firstly, two identical connection interfaces are subjected to a certain thermal pre-treatment, and then heated by a heating plate. In this process, the temperature of the heating plate must be determined and adjusted so that it can be at a suitable temperature. Heating the interface and connecting the interface to a viscous flow is considered successful. When the heating is successful, the heating plate is removed and a certain pressure is rapidly applied to the interface so that the connected interface can be well cooled and solidified, so as to achieve a firm connection, and the interface is completely solidified and released. The pressure board will be done.

Pe pipe welding precautions

1 There are many things to pay attention to in the hot melt, for example, the size of the curl and the degree of cleanliness of the curl are all very important, and the curled welding interface can't crack or bend to the back. Phenomenon, these factors will affect the effect of welding. Of course, it should also be noted that the phenomenon of leaching of dissolved substances from the fittings cannot occur during the fusion process, and the fittings and fittings must also be in a straight line.

2 When welding, it is important to pay attention to the parameters of the time, temperature, and pressure, and the specific conditions of the changes. But also to fully consider the interface interface material properties, geometry, stress state and welding environment factors, in order to better protect the welding effect.

3 Before welding, pay attention to the pipe to be welded in order to achieve the purpose of removing impurities and oxide layer, and also to ensure the smoothness and smoothness of the two ends of the butt joint, and the smaller the wrong side of the two welded pipe segments, the less stress. The more concentrated it is, the better the welding effect will be. When the welding of the interface is completed, remember to perform the fusion butt joint immediately, that is, shorten the cycle as much as possible to ensure the welding quality.


Pe pipeline construction plan

First, preparation before construction

(1) The construction unit should have corresponding qualifications, and the engineering construction personnel should have the professional installation technical qualifications.

(2) The construction drawings and other relevant technical documents are available and approved by the meeting; and there are design units who have made technical disclosures.

(3) The material to the construction site meets the design requirements, and the construction equipment and on-site environment can ensure normal construction.

Second, transportation and storage

(1) PE pipe is easily scratched by sharp objects, etc., and an important factor causing stress cracking during operation is scratched on the surface.

(2) Long-term intense sun exposure will accelerate the aging of pipes and shorten their service life.

(3) Oils, acids, alkalis, and salts, especially active organic compounds attached to the pipe, will make it in operation. Under certain conditions, the resistance to environmental stress cracking will be reduced.

Third, PE pipe hot melt welding (injection socket connection, fused socket connection, hot melt saddle welding connection) and butt welding (injection, docking) technical points.

(1) The broken material of the pipe should be measured according to the length of the measured pipe. Cutting tools should use special pipe cutters and cutters. Pipes with dn≥40mm should be mechanically broken. After the material is cut off, the section of the pipe should be smooth and burr-free, and the section should be perpendicular to the axis of the pipe.

(2) In the hot melt butt jointing tool, the two corresponding parts to be connected should be straightened so that they are on the same axis, and the wrong side should not be more than 10% of the wall thickness.

IV. General Rules for Pipeline Installation

1. Polyethylene (PE) pipes are connected to steel pipes, but when flanged, they should meet the following requirements:

(1) A steel flange piece shall be welded to the end of the steel pipe to be connected in accordance with the flange connection requirements of the metal pipe.

(2) Another steel flange piece (back pressure flange) shall be fitted over the end of the PE flange connection (pipe end) to be connected.

2. The installation of buried PE water supply pipes shall meet the following requirements:

(1) The width of the bottom of the pipe when laying a single pipe is: dn+0.3m (dn is the outer diameter of the polyethylene pipe), and the double pipe is laid: dn1+dn2+s+0.3m (s=design clearance between the two pipes);s Value 0.2m (recovery fused tube).

(2) When the PE pipeline is connected underground, the width of the bottom of the pipeline should not be less than 700mm. The depth of soil covering the top of the pipe shall not be less than 0.8m when it is buried under the roadway; it shall not be less than 0.6m when it is buried under the non-roadway; it shall not be less than 0.8m when it is buried under the farmland and paddy field. (Different anti-freezing zones in different places should be adjusted according to the actual situation)


V. Quality acceptance

1. In the middle of acceptance, after installation of concealed pipelines is completed, water pressure or air pressure tests are carried out by the construction unit in conjunction with the supervision unit.

2. Overall acceptance of the overall acceptance conditions:

(1) Construction drawings, as-built drawings and design change documents.

(2) Site acceptance records for pipes, fittings and quality assurance materials.

Sixth, finished product protection requirements:

1. The PE pipe that is completed after construction is strictly prohibited from hitting or nailing metal nails and hitting or heavy objects on the pipe.

2. In order to prevent the PE pipe from freezing, it is forbidden to have water retention during use.

Seventh, hydrostatic pressure test Press the following steps:

1. The pipeline should be slowly injected from the downstream, and the exhaust point should be set at the top of the upstream pipe and the pipeline.

2, according to the design work pressure 1.5 times the hydrostatic test, but the cold water pipe shall not be less than 0.6MPa, the pressure rise time is not less than 10min, the pressure accuracy of the measuring instrument shall not be less than 0.01MPa.

Editing Summary: PE pipe welding requires attention to many places, if not carefully carried out, then it is easy to have a certain impact, and accurately grasp the welding technology, can greatly improve the quality of welding, but also to a great extent to extend the PE pipe Service life.

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