What is large diameter heat shrink tubing?

Heat shrink tubing is essential for wire protection and bundling, but in recent years, there has been increasing demand for large-diameter products (Φ30mm or more). Large-diameter types are useful in environments that handle large structures, such as processing thick cables, pipes, and harnesses with connectors. Here, we will provide a clear explanation of the features, selection points, and products we offer for large-diameter heat shrink tubing.

1. Features of Large-Diameter Heat Shrink Tubing

● Can cover large objects in one go

While general heat shrink tubing primarily ranges from Φ1 to 20mm, large-diameter products can accommodate sizes from Φ30mm up to Φ400mm. They can be applied in one go to bundled cables, thick hoses, pipes, and more.

● Many products have a high shrink ratio

Even with large diameters, many products support a shrink ratio of 2:1 to 4:1, allowing them to conform to a wide range of object sizes. This is particularly effective for fitting over areas with steps (such as connectors or terminals).

● Excellent insulation and mechanical protection

Although it depends on the material, most commonly use polyolefin-based materials, offering excellent insulation, abrasion resistance, and weather resistance. Additionally, by choosing thick-walled types or flame-retardant grades, they can be used safely in outdoor applications and around heavy machinery.

2. Examples of Applications

Protection of power cable branches
Main cable processing for distribution boards and busbar insulation
Protection and identification of thick hoses and pipes
Terminal processing for large equipment in factories

3. Checkpoints for Selection

Maximum outer diameter of the objectSelect a size with sufficient allowance beyond the pre-shrink inner diameter of the heat shrink tubing.

Shrink ratioSelect based on how tightly you want it to fit after shrinking (e.g., 3:1 or 4:1). A high shrink ratio is effective for areas with large steps.

Operating environmentSelect the material based on whether outdoor, high temperature, oil resistance, or flame retardancy is required (e.g., weather-resistant grade).

Minimum recovered diameterConfirm that it fits snugly around the object after shrinking. The wall thickness of the tubing also needs to be considered.

Shrinkage temperature and heating methodVerify that the product's shrinkage temperature is compatible with the heating method, such as a heat gun or torch. Large diameters take longer to heat, so a method that provides uniform heating is recommended.

4. How to Choose Large-Diameter Heat Shrink Tubing (Φ50 or more)

When dealing with diameters exceeding Φ50mm, it becomes more common for products to fall outside standard heat shrink tubing specifications. Here are some key points to pay attention to during selection.

● Wall thickness and shrink ratio are important considerations

For diameters of Φ50 or more, even with the same "2:1 shrink ratio," the minimum diameter after shrinkage will be larger. Therefore, always check the dimensional chart to ensure it will adhere closely to the object. For example, a 2:1 product with a pre-shrink diameter of Φ80 will have a minimum post-shrink diameter of Φ40. If the object's outer diameter is Φ45, it will fit well. However, if the object is Φ39, it will not adhere tightly, so you would need to choose a product with a shrink ratio of 3:1 or higher.

● Heating method and ease of installation

The larger the diameter, the more difficult it becomes to heat the entire tube uniformly. When using a heat gun, the basic method is to move it slowly in a circular motion from the outside. While a torch burner heats faster, it carries the risk of uneven shrinkage or scorching due to localized heating, so extreme caution is required, especially for Φ50 or larger.

● Utilizing adhesive-lined types (waterproof specification)

For applications involving Φ50 or more, terminal waterproofing and dust protection are often required. By choosing a waterproof type with hot-melt adhesive coated on the inside, the adhesive adheres to the object after shrinking, providing high waterproof performance. Our CDM (large-diameter waterproof heat shrink tubing) is designed for this purpose.

※ Products with Φ50 or more are available as in-stock items or made-to-order. Please contact us for details.

5. Large Diameter Product List

If you want to apply heat shrink tubing to cables with connectors or terminals already attached, or to branch points or T-joints, it can be difficult with regular tubular tubing because it needs to be threaded from the end.

● Our large-diameter products compatible with post-installation

Large Diameter・Waterproof・Post-Installation Compatible

Large Diameter Waterproof Heat Shrink Tubing CDM (Adhesive-lined)

For waterproofing, insulation, and terminal processing of large-diameter cables. Provides high adhesion and waterproofing with adhesive lining. Proven track record in power and infrastructure applications.

Compatible Diameter: Large Diameter Shrink Ratio: 3:1 Adhesive: Yes

View Product Details›

General Purpose・Large Diameter

Heat Shrink Tubing Large Diameter Collection

You can view a list of our large-diameter heat shrink tubing. Filter by size, shrink ratio, and material.

Compatible Diameter: Φ30~ Shrink Ratio: 2:1 / 3:1 / 4:1

View Large Diameter Collection›

For details on post-installation compatible products and stock availability, please feel free to contact us via the inquiry form.

6. Denka Electron's Proposal

We offer large-diameter heat shrink tubing compatible with diameters from Φ30 to Φ400mm. We can also provide OEM solutions with a focus on Japanese quality, and we are flexible in handling small-lot orders, custom cuts, and printing services.

"I don't know which size to choose."
"I need a thick product for outdoor use."
"I need flame retardancy but also flexibility."

For such inquiries, our specialized staff will offer the optimal solution.

Summary

Large-diameter heat shrink tubing is ideal for protecting and insulating thick sections that conventional tubing cannot handle. By selecting the correct size and material, it is possible to achieve highly installable and reliable wiring treatment. For selecting products of Φ50 or more and post-installation compatible products, we recommend consulting our staff in addition to checking the dimensional chart.