HDPE pipe and fitting,PVC pipe and fitting

HDPE (high-density polyethylene) pipes are widely used in water supply and drainage, gas transmission and other fields due to their corrosion resistance, good flexibility and long life. Electrofusion welding is one of the common connection methods for HDPE pipes, but various problems may be encountered in actual construction. This article will introduce the common problems, cause analysis and solutions in electrofusion welding in detail to help improve the construction quality.

 

Basic principles of electrofusion connection

Electrofusion connection is to heat the HDPE material through the resistance wire inside the electrofusion sleeve (or electrofusion pipe fitting), and form a high-strength sealed joint after cooling. The key steps include:

Pipe end surface treatment (scraping oxide layer, cleaning)

Centering and fixing (avoid eccentricity)

Electric heating (control time and voltage according to manufacturer parameters)

Cooling and curing (natural cooling to avoid external interference)

 

Common problems and solutions

1. The electric fusion joint is not firm or leaking

Possible reasons:

The oxide layer on the pipe end surface is not scraped clean, resulting in poor fusion

The electric fusion time is insufficient or the voltage is unstable, and the melting temperature is not reached

External force disturbance during cooling

Electrofusion pipe fittings or pipe materials are unqualified (such as doped recycled materials)

Solution:

Strictly handle the pipe end surface:

Use a special scraper to remove the oxide layer (scraping length ≥ electric fusion sleeve insertion depth)

Wipe with alcohol or a clean cloth to ensure that there is no oil or dust

Control heating parameters:

Set the welding machine according to the voltage and time provided by the manufacturer (different pipe diameters and ambient temperatures need to be adjusted)

Use a stabilized power supply to avoid voltage fluctuations

Ensure sufficient cooling:

Cooling time ≥ specified value (usually 20-30 minutes)

It is forbidden to move the pipe or apply pressure during cooling

Select qualified materials:

Purchase HDPE pipes and electric fusion pipe fittings that meet GB/T 13663 standards

Avoid using inferior or recycled materials

2. Smoke or fire during electric fusion

Possible causes:

Resistance wire short circuit or local overheating

Electrofusion pipes damp or internal contamination

Input voltage too high

Solution:

Check the electric fusion pipes:

Before use, check whether the internal resistance wire is intact, without breakage or deformation

Before construction in a humid environment, use a hot air gun to dry the pipes

Control voltage:

Ensure that the output voltage of the welding machine is consistent with the nominal value of the pipe (usually 39.5±0.5V)

Avoid long-term overload power

Emergency treatment:

Immediately turn off the power, replace the pipes and re-weld them after cooling

3. The observation hole is not ejected or ejected unevenly

Possible causes:

Insufficient heating time, material is not fully melted

Insufficient pipe insertion depth or large deviation in centering

Ambient temperature is too low (such as winter construction)

Solution:

Adjust construction parameters:

Extend heating time in low temperature environment (refer to manufacturer"s low temperature welding parameters)

Ensure that the pipe insertion depth is aligned with the electric fusion sleeve mark

Check centering:

Use a clamp to fix the pipe to avoid eccentricity (deviation ≤10% wall thickness)

The ejection height of the observation hole should be uniform (generally protruding 1-3mm)

4. The internal diameter of the joint is reduced or blocked after electric fusion

Possible causes:

Excessive accumulation of molten material inside the joint

The pipe port is not chamfered, and the molten material does not flow smoothly

Solution:

Pre-treat the pipe port:

Use a chamferer to process a 15° groove after cutting

Ensure that there are no burrs on the inner wall of the pipe

Control the amount of fusion:

Avoid overheating (operate according to standard parameters)

Electrofusion connection is a key link in the HDPE pipe system, and quality problems may cause leakage or structural failure. The failure rate can be significantly reduced by standardizing operations (cleaning, alignment, parameter control), selecting qualified materials, and strengthening construction management.

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