What are the requirements for storage environment temperature of HDPE socket fusion fitting

HDPE socket fusion fittings are widely used as an important component in municipal engineering, gas transmission and distribution, water conservancy facilities, agricultural irrigation and industrial fluid transportation systems. They are favored for their good corrosion resistance, flexibility and hot-melt connection performance. In order to ensure that they play their due functions in construction and operation, and to ensure that the socket fusion fittings do not undergo physical deformation, performance degradation or structural damage during storage, it is crucial to reasonably control the temperature conditions in the storage environment.

Thermophysical properties of HDPE materials
HDPE is a thermoplastic polymer with a certain degree of thermal sensitivity. Its glass transition temperature is low, the melting point is generally between 130℃ and 135℃, and the long-term use temperature generally does not exceed 60℃. At higher temperatures, HDPE materials will gradually soften, resulting in decreased dimensional stability and weakened structural strength; at lower temperatures, embrittlement may occur due to material shrinkage. These properties determine that HDPE socket fusion fittings must be kept within a specific temperature range during storage to avoid irreversible changes in performance.

Recommended storage temperature range
The ideal storage environment temperature for HDPE socket fusion fittings should be controlled between -10℃ and 40℃. This temperature range can effectively avoid the stress concentration and deformation risks caused by the thermal expansion and contraction effect on the pipe structure. Especially in high temperature and high humidity environments, if the storage temperature exceeds 40°C, the material may soften locally or produce slight flattening, stretching, cracking and other problems due to stacking pressure, which seriously affects its subsequent welding and sealing performance.
In cold areas or seasonal low temperature environments, the storage temperature should not be lower than -10°C. When the temperature is lower than -20°C, the risk of low-temperature embrittlement of HDPE materials increases significantly. If it is hit by external forces during transportation, it is very easy to cause cracks or microstructural damage. In addition, the installation and construction of socket fusion fittings under extremely low temperature conditions will also face hidden dangers such as uneven welding and insufficient weld strength.

Impact of high temperature environment on storage
When HDPE materials are stored in high temperature environments, they are prone to local softening or thermal aging due to heat accumulation. Especially in storage spaces with direct sunlight and poor ventilation, the surface temperature of socket fusion fittings may be much higher than the ambient temperature, resulting in deformation due to uneven thermal stress. Thermal aging may also accelerate the oxidative degradation of HDPE molecular chains, causing the surface of the pipe to turn yellow and become brittle, shortening its service life.
When the storage temperature exceeds 50°C continuously, cooling measures should be taken, including strengthening ventilation, using air conditioning systems, or moving the pipes to a cool and dry area. If the storage environment cannot meet the temperature control conditions, the storage time should be limited to avoid long-term exposure of the pipes to high temperatures.

Impact of low temperature environment on storage
Under low temperature storage conditions, HDPE pipes are prone to volume shrinkage, causing dimensional deviations. Especially for socket hot-melt pipes, slight deformation of the interface may affect the insertion force and fusion tightness during the welding process. If the storage temperature is too low, the interface material may become hard and brittle, resulting in cracks during insertion, and even risks of leakage and falling off after welding.
After the pipes are taken out of the low temperature environment, they should be properly treated to recover the temperature before construction. Leave the pipes at room temperature for 4-8 hours to make their temperature close to the construction environment temperature, so as to ensure the welding quality during the welding process.

Structural stress risk caused by temperature difference
Environments with large temperature differences (temperature difference between day and night exceeds 15°C) pose a hidden danger to the storage of HDPE socket fusion fittings. Repeated thermal expansion and contraction may cause micro cracks or slight loosening of the interface, especially for multi-layer stacked socket fusion fittings. The concentrated load after thermal expansion can easily cause deformation of the lower layer or uneven support. It is recommended that in areas with large temperature differences between day and night, socket fusion fittings should be stored in a warehouse with good thermal insulation performance, and buffer materials such as foam pads and wooden brackets should be added to the stacking to buffer stress transfer.