Storage Conditions And Maintenance of Cold&Heat Cable Shrink Accessories

As we all konw, heat-shrink and cold-shrink accessories’ performance is not just determined by how they are installed, but influenced by how they are stored before they are ever used.

 

In fact, storing these accessories isn't like storing spare lumber or bricks. It's more akin to preserving a fine chemical reagent or a sensitive photographic film. The polymers and adhesives inside are in a state of suspended animation, and our job is to keep them that way until the moment of use.

 

Environmental Degradation

 

First of all, to understand the storage requirements, we must first understand what we're protecting these accessories from. The primary information are heat, oxygen, ozone, ultraviolet (UV) light, and moisture. These elements initiate and accelerate chemical reactions that permanently alter the material properties.

 

As we all kown, heat-shrink tubing is made from cross-linked polyolefins. Heat provides the energy for the "shape-memory" polymer to return to its original, pre-expanded form. Storing them in a hot environment provides a low, constant energy input, causing them to slowly relax and shrink prematurely. Furthermore, heat accelerates the oxidation of the polymer, making it brittle and less flexible over time. In addtion, cold-shrink tubing is typically made of EPDM or silicone rubber, pre-expanded and held on a removable plastic core. The core is under constant tension, and the rubber is held in an energetically unstable state. Heat, just as with heat-shrink, can cause the core to relax or distort and can degrade the rubber's elastic properties. Internal Adhesives and Mastics often feature a sealant or adhesive layer on the inside. Heat can cause these mastics to soften, bleed, and migrate, creating a messy, uneven layer that fails to seal properly. Cold, on the other hand, can make them hard and non-tacky, preventing them from forming a waterproof bond during installation.

 

Temperature

 

Ideal range is cool temperature between +5°C to +25°C (41°F to 77°F) is ideal. This range is low enough to slow down polymer degradation and adhesive migration. Avoiding Extremes temperture. Otherwise, as high temperatures (>30°C / 86°F) promotes premature shrinkage which due to core migration in cold-shrink products, adhesive bleed-out and accelerated aging of the rubber or plastic. And as low temperatures (<0°C / 32°F) is a extreme cold which can make polymers temporarily brittle and increase the risk of cracking during handling. More critically, it can ruin the sealants leading to an incomplete seal.

 

In addtion, stability is Key that fluctuating temperatures can be as harmful as a consistently high temperature.

 

Humidity

 

Water vapor is a persistent and insidious threat. Ideal Relative Humidity (RH) is less than 60%. Many cable accessories are used with connectors and lugs made of Aluminum or copper. Moisture in the air will cause these to corrode, leading to a poor electrical connection and increased resistance at the joint. In addtion, Moisture can contaminate the adhesive surface, preventing it from sticking to the cable jacket. What’s more, if moisture permeates the packaging and settles on the inner surface of an insulator, it can create a conductive path whicg leading to a short circuit or catastrophic failure when energized.

 

Light

 

The ultraviolet radiation in light is a powerful degrader of polymers. Store all accessories in their original opaque packaging. If the original box is damaged, use an opaque plastic bin. UV photons have enough energy to break the chemical bonds in the long polymer chains that give the material its strength and flexibility. This leads to chalking, surface cracking, embrittlement even a loss of electrical insulation properties.

 

Stacking

 

Stack heavy items on top of cable accessories can cause heat-shrink to fuse together or deform. In addtion, the immense pressure can cause the plastic core of cold-shrink to collapse or distort  due to rendering the product useless. Storing them vertically for long periods can cause the core to slowly slide down under gravity, leading to bulging at one end and potential collapse. Heat-Shrink Tubes’ horizontal storage is generally recommended to prevent any deformation or stress concentration.

 

Chemical Environment

 

Keep Away From Ozone generators, solvents, fuels, oils and corrosive chemicals. Ozone, in particular, is a powerful oxidizer that attacks the double bonds in rubber molecules (like EPDM and natural rubber), causing surface cracking. Proper storage isn't a "set and forget" operation. It requires proactive management.

 

Implement a strict inventory management system. Use the oldest stock first to prevent any product from exceeding its shelf life. Always check the manufacturer's stated shelf life, typically 2 years from the date of manufacture when stored under recommended conditions. This date is based on accelerated aging tests and is a reliable guide. This is a crucial and often overlooked step. If your storage area is not climate-controlled and the accessories have been subjected to cold temperatures (<5°C / 41°F), they must be "cured" or acclimatized before use. Don’t open immediately. Bringing a cold accessory directly into a warm, humid environment will cause condensation to form on its cold surface, introducing the very moisture you've worked hard to avoid. The Correct Method: Leave the accessory in its sealed, original packaging and allow it to gradually warm to the ambient installation temperature over a period of12 to 24 hours. Only then should you open the package. This ensures the components are warm, dry, and ready for a perfect installation.