How to Weld Steel Wire Reinforced Thermoplastics Composite Pipe?

Posted on: July 29, 2021 by Madison Pipe Industry, 6 min read

The steel wire reinforced thermoplastics composite pipe is a new type of improved steel frame plastic composite pipe. With high-quality materials and advanced production technology, the high-performance HDPE modified bonding resin is closely connected to the metal steel wire mesh skeleton and the inner and outer high-density polyethylene materials. It has good flexibility while taking into account strength. Suitable for long-distance buried water supply and gas pipeline systems. It is a new type of environmentally friendly pipe formed by continuous extrusion of hot-melt adhesive compound, which not only retains the advantages of high stability of steel pipes, but also retains the characteristics of plastic pipes' hygienic performance, technical reliability and long service life.

Weld Steel Wire Reinforced Thermoplastics Composite Pipe

How to Weld Steel Wire Reinforced Thermoplastics Composite Pipe?

1. Welding Precautions

If cutting is required during use, the port must be impervious and sealed with PE hot-melt glue gun. Before power on, the axis at the direct head shall be calibrated to be on the same line with the pipe. Before power on, check whether the wire connection is correct and whether the cross-sectional area and capacitance of the wire meet the relevant requirements of the electric fusion welding machine. During welding and cooling, the parts of the joint and the pipes on both sides shall not be moved or rotated. Before welding, check whether the copper parts of pipe fittings and joints are clean and free of stains. If there is smoke during welding, turn off the power supply immediately. If the pipe parts assembled on the same day are not welded, protective measures must be taken at night to prevent rain (DEW) from immersing the pipe parts at night. Special attention shall be paid to the construction personnel to prohibit construction operation on rainy days.

2. Welding Principle

The determination of welding process is set under certain environment, temperature and conditions. Under different ambient temperatures, the parameters shall be adjusted appropriately according to the actual situation.] Constant voltage welding: pay attention to the current change on the control panel of the electric fusion welding machine during welding, and the current value will gradually decrease from the beginning of welding to the completion of welding. Principle: when the welding machine is in constant voltage welding, the voltage is a constant value, the resistance of copper wire becomes larger and the current must become smaller in the process of melting and heating. Under special circumstances, if the "current suddenly increases (does not decrease but increases)" is found during welding, the power supply must be turned off immediately for inspection to prevent over welding and false welding due to spraying and smoking. At this time, the copper wires (resistance wires) in the electric melting pipe fittings are immediately connected in parallel (Series wires), and the resistance decreases, so the current suddenly increases.

3. Welding Process and Procedure

Step 1: Prepare tools needed for welding steel wire mesh skeleton pipe: electric welding machine, PE hot melt welding gun, polishing machine, cutting machine, tape, hammer, flat scraper, marker pen, sandpaper and towel.

Step 2: According to the actual requirements, the pipe cutting customers can use professional cutting machine to cut the pipe. The cutting end face shall be flat and perpendicular to the axis of the pipe. It is strictly forbidden to cut by open fire. The port is polished with a grinder to ensure the flatness of the port. Then, the PE hot melt glue gun is used to seal the port impervious. Check whether the port is sealed evenly to ensure that there is no copper wire exposed.

Step 3: Mark the length to measure the depth of pipe socket, and mark the corresponding length of pipe spigot end.

Step 4: Scrape the surface of the pipe with a flat scraper (it is forbidden to use a grinder) to scrape the oxide layer off the surface of the pipe. When scraping, the surface of the pipe end shall be scratched along the whole outer circumference of the pipe end, and the surface of the socket end of the electric melting pipe shall be polished and removed with sandpaper (the oxide layer can be scraped off by 0.1-0.2mm).

Step 5: Clean the pipe with dry towel (it is forbidden to use wet towel) to wipe the remaining debris from the pipe parts when scraping the oxide layer, to avoid the influence of welding quality due to impurities and keep the connection surface free from moisture.

Step 6: Insert the pipe fittings and handle the pipe parts according to the above steps, and hammer the pipe fittings into the pipe mark( When the matching is tight, it should be knocked to the bottom slowly).

Step 7: After setting welding parameters and matching all the welding parameters, input welding parameters (constant pressure welding or constant current welding) strictly according to the parameters requirements on the electric melting pipe fittings. It is advisable to use constant pressure welding (for example, the process parameters of a pipe fitting shall be displayed as: Welding voltage 39.5v, Welding time 140 seconds) the detailed welding machine parameter setting should carefully check the white barcode on the outside of the pipe fitting. After checking, insert the copper electrode of the welding machine into the electric melting pipe fitting (it must ensure that the pipe parts are not shaken or falling off during welding).

Step 8: After the connection reaches the welding time, natural cooling shall be carried out according to the cooling time requirements of process barcode. During the fusion and cooling process, the parts of joints and pipelines on both sides shall not be moved or rotated.

4. Special Reminder

Before welding the steel wire mesh skeleton pipe, the pipe parts shall be inspected and replaced in time if any problem is found.

The precautions for the welding of electrofusion pipe fittings with steel mesh framework of our company are as follows:

1.Welding mode

Constant pressure welding mode is preferred.

2.Welding machine selection

It is suggested that the electric fusion welding machine meeting the requirements of the national standard GB / t20674.2-2006 should be preferred, and the electric fusion welding machine should output AC(3.5kw welding machine shall be used for pipe diameter below dn315 (including), and 7.5kW welding machine shall be used for pipe diameter above dn315)

3.Before the maintenance of welding machine, it is recommended to overhaul the welding machine, focusing on the following contents:

  • Whether the output voltage of the welding machine is stable within ± 0.5V of the set value.

  • Is the output voltage DC or AC.

  • Whether the plug of the welding machine is complete and clean, and whether the inner diameter size matches the copper electrode of the pipe fitting.

  • Whether the welding machine has automatic temperature compensation function. If not, it is necessary to teach the construction personnel to adjust the actual welding time according to the ambient temperature. The welding time of electric melting pipe fittings is based on the ambient temperature of 20 ℃. The corresponding welding time shall be reduced by 4% for every 10 ℃ increase in the ambient temperature, and the corresponding welding time shall be increased by 4% for every 10 ℃ decrease in the ambient temperature.

  • The welding machine shall have self-protection functions such as undervoltage, overvoltage, undercurrent and overcurrent, and shall be able to alarm automatically in case of any fault.

  • The welding machine shall have the function of automatic bar code scanning, and the bar code pasted on the pipe fittings shall be preferentially used for scanning and welding, so as to avoid welding failure caused by human input error.

  • Whether there are exposed parts of welding wire, plug and other metal parts to avoid potential personal safety hazards.

4.Power selection

  • Fixed power supply is preferred. When two-phase power supply is adopted, the power supply voltage should be between 180v-240v, and different welding machine manufacturers have different requirements.

  • If the generator power supply is required, the generator power shall be more than twice the welding machine power.

  • The length of power line should be ≤ 20m, and the line thickness should be ≥ 3M2.

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