How to Solve Low-temperature Brittleness of PE Pipes? Notes for Storage, Transportation and Installation

PE pipes have good comprehensive mechanical properties, yet polyethylene material has the inherent feature of low-temperature brittleness. When the ambient temperature drops, the material loses toughness and becomes more prone to cracks and damage under impact, collision or bending. Pipe failures frequently occur during winter construction and in cold northern regions. Many pipe cracking cases under low-temperature conditions are not caused by unqualified products, but mostly by improper operations in storage, transfer, hoisting and installation. Based on the properties of polyethylene, this article introduces protection strategies and site control points to reduce PE pipe damage in cold environments.

Storage is the first line of protection. Pipes shall be stacked on flat and solid ground. Keep stones and sharp sundries away from the pipe surface to avoid local stress concentration. For outdoor stacking, cover the pipes properly to reduce repeated temperature changes caused by day-night temperature difference and prevent long-term snow and ice accumulation on pipe surfaces. Stack height should be controlled to avoid continuous compression load on bottom pipes. In cold seasons, shorten outdoor storage time as much as possible and move pipes into enclosed warehouses if available. Sort pipes by specification and batch, keep end caps intact to stop sediment and water from entering. Do not stack pipes directly on frozen or icy ground. Flexible bedding can be laid underneath to reduce cold transfer and impact from hard objects.

Impacts during transportation and loading are major causes of pipe damage. Under low temperature, never drop or drag pipes from height. Use flexible slings for hoisting instead of steel wire ropes, as sharp wire rope edges may scratch the pipe wall. Keep vehicle interiors flat and add soft pads where pipes contact sharp corners of the carriage. Secure pipes after loading to prevent sliding and collision during transit. Protect protruding sections when pipes of different lengths are loaded together. Loading and unloading should be arranged during warmer daytime hours rather than early morning or night when temperatures are lowest.

On-site installation control is equally important. Hot melt welding of PE pipes is suitable within a proper temperature range. Hot melt work is not recommended when the temperature is extremely low. If construction must proceed for schedule reasons, set up windproof and thermal sheds and preheat pipe joints gently. Never use open flame to heat pipes, because open flame leads to local material aging and performance change. PE pipes turn harder at low temperatures. Do not force sharp bending, which may form hidden internal cracks. Inspect each pipe visually before lowering into trenches to check for dents and microcracks. Damaged pipes should not be installed. Trench bottoms shall be compacted and levelled, with sharp stones removed and fine sand bedding laid for uniform support. Backfill in layers. Fine soil or sand shall be used for the first backfill layer; large frozen soil blocks and stones cannot fall directly onto pipes.

Construction schedules can also be adjusted reasonably. In cold regions, arrange pipe laying and welding during warmer hours. After pipes are moved from cold storage to working areas, do not weld immediately. Allow enough time for temperature stabilization to reduce internal stress from temperature difference.

In conclusion, low-temperature brittleness is an inherent property of PE materials and cannot be eliminated completely. Standardized storage, gentle handling, reasonable construction scheduling, joint protection and sand bedding can effectively reduce cracking risks. Proper protection throughout all stages helps maintain the long-term stability of PE pipeline systems.