Accurate Inspection Of Heat Shrinkage Pipe Inner Diameter Distinguishing Heat Shrinkage Cable Accessory Material

- Apr 10, 2019-

Plug gauge (or mandrel) is commonly used to accurately measure the inner diameter of heat shrinkable pipe. Plug gauge is put into the pipe and there is no gap around it. The mandrel should be easily put in and pulled out of the pipe. The outer diameter value of plug gauge is the inner diameter value of casing. The inner diameter value of heat shrinkable tube usually retains only one decimal point (unit mm), and it is also used for projector equipment detection. For larger size casing, an empirical formula for inner diameter measurement is: inner diameter folding diameter 1.57 (where folding diameter refers to the width of casing flattening and folding).

How to accurately detect the wall thickness of heat-shrinkable tube, such as double-wall heat-shrinkable sleeve, professional and accurate method using wall thickness gauge or projector to test, can avoid artificial errors, heat-shrinkable tube itself has a certain elasticity, generally used to use vernier caliper to measure, but in the process of measurement need to master the measurement techniques, the weight of the techniques will obviously affect the results of the test, heat-shrinkable tube. In wall thickness industry, the average wall thickness is calculated [mean wall thickness = maximum value + minimum value)/2, and the same heart rate of wall thickness is more than 70%, the same heart rate = minimum value of shrinkable tube / maximum value * 100%].

After cutting the heat shrinkable pipe, the number of meters is often less. Customers found a few phenomena after cutting the heat shrinkable casing, which is usually tens of meters or more less according to the number of cutting sections. This is a normal phenomenon. The reasons are as follows: 5000M cutting 10 mm per section, a total of 500,000 sections. In general, the size of pipe-cutting is controlled in the range of 10.1 mm to 10.5 mm, so the length of heat-shrinkable sleeve required by actual calculation is: 500000 * 10.1 = 5050 m or 500000 * 10.5 mm = 5250 m, plus abnormal loss of pipe-cutting, in general, the heat-shrinkable sleeve is needed to cut 500,000 segments in the range of 5050 M to 5250 m, so when using 5000 m pipe to cut, there will be a phenomenon of fewer tubes (except the case of insufficient package volume).

Cold-shrinkable cable accessories, commonly known as cold-shrinkable cable head, are made of elastomer materials (commonly used silicone rubber and ethylene propylene rubber) by injection vulcanization in the factory, then expanded and lined with plastic spiral to support double-wall heat-shrinkable tubes to form various cable accessories. Conventional materials are silicone rubber and ethylene propylene rubber. Heat shrinkable cable accessories, commonly known as heat shrinkable cable head, are widely used in the intermediate connection and terminal of 35KV and the voltage level below the heat shrinkable cable accessories or oil-immersed cables. Compared with traditional cable accessories, it has the advantages of small size, light weight, safety and reliability, and easy installation. This kind of product mainly uses stress tube to deal with the problem of electric stress concentration. That is to say, the parameter control method is used to alleviate the stress concentration in the electric field. The product meets the GB11033 standard. Its long-term service temperature ranges from - 55 105 and its aging life is 20 years. Its radial shrinkage rate is more than 50%, longitudinal shrinkage rate is less than 5%, and shrinkage temperature is 110 140 C. The materials used for thermal shrinkable cable accessories are usually blends of polyethylene, ethylene-vinyl acetate (EVA) and ethylene-propylene rubber.

Cable cleaning paper is refined from imported spunbonded fabrics, deionized water and professional secret formula of professional organic solvents for environmental protection pure aluminium bags. This product is used as raw material for special high temperature heat shrinkable pipe, no chip, no water mark, no need to dry, efficient decontamination, strong friction, insulation and anti-conductive. The grease and dirt on the cold and heat shrinkable accessories of wires and cables can be removed immediately by gentle wiping. When cleaning cables and cable accessories, attention should be paid to the direction of cleaning. The correct method is to start from the end of the conductor and clean it downwards, not back and forth. Back and forth cleaning can easily leave the tiny carbon particles in the semi-conductive layer on the main insulation and reduce the insulation performance.

Silicone grease paste is a colorless translucent Organic Silicone Grease Paste Compound made by special process, which is made of high purity inorganic thickener, modified silicone oil, ultra-pure insulating filler and functional additives.

Silicone grease paste is used in high voltage cable accessories (power cable joints and switch accessories above 10 kv) and electrical insulators to prevent corona release and eliminate arc, and to insulate, resist creeping, seal lubrication and moisture resistance. When making cable heads, silicone grease should be applied to all areas where the surface contacts with the surface. Its function is insulation, sealing and lubrication.