Obviously, from the name of the double-wall heat shrinkable tube and single-wall heat shrinkable tube is a difference is: double-wall heat shrinkable tube is a double layer, while the ordinary single-wall heat shrinkable tube only one layer, then, single-wall and double-wall is exactly what they produce the difference in performance, the following is a detailed description.
The production process of single-walled heat shrinkable tube is that the polymer or polymer alloy is extruded to obtain a tubular intermediate product, and then heated and expanded after irradiation cross-linking, cooling and shaping to obtain a certain size of tubular products. Single-wall heat shrinkable tube has the advantages of easy shrinkage, softness, environmental protection and flame retardant, but single-wall heat shrinkable tube cannot be used in wet environment.    
Double-walled heat shrinkable tube is composed of outer wall of tube and inner layer of hot melt adhesive, the outer wall is irradiated cross-linked, flame retardant polyolefin, and the inner layer of hot melt adhesive, which melts when heated, can play the role of sealing water-proof, rust-proof and corrosion-proof, it has a large working temperature range and can seal different kinds of cable harnesses. The hot melt adhesive can form an effective barrier against water and vapor. It protects the cable from corrosion and water seepage. Double-walled heat shrink tubing has many shrinkage multipliers, and a few specification models can seal a larger diameter range of joints and components.
There is also a difference in placement criteria.
When you place single-wall heat shrink tubing and double-wall heat shrink tubing together for an extended period of time, you may find that the single-wall heat shrink tubing works while the double-wall tubing does not. Such a situation is also caused by the hot melt adhesive of the double-walled tube. Because there is a requirement for the placement of hot melt adhesive, there is a difference in the placement criteria for double walled heat shrinkable tubes and single walled heat shrinkable tubes.
Of course, double-wall heat-shrinkable tube and single-wall heat-shrinkable tube have differences with the same place.
1, in line with RoHS, UL and other environmental norms
2, excellent hot melt adhesive and high shrinkage ratio provides excellent sealing
3 Soft, outer layer flame retardant
4 Heat shrink multiplier: 2:1, 3:1, 4:1, can be used as insulation and sealing protection for non-regular shaped objects