Srwpe Hot Melt Extrusion Welding Heat Shrinkable Sleeve Connection Technology Research And Application

In recent years,polyethylene pipes are widely utilized in municipal engineering construction.A considerable portion of the connector is connected by a heat shrink belt connection or a hot melt extrusion connection.These two methods are not only simple and fast to operate,but also good connection with low cost.However,there are many defects when the two methods are used separately,and the connection reliability is relatively insufficient.In order to obtain the excellent effect of the integrated connection,this paper is focus on the study of two methods' composite application.At present,there are few cases of compound use cases in municipal engineering.Therefore,there are no construction work guides,acceptance criteria or systematic technical specifications about composite connection method.From the literature,there is almost no composite connection method of research results.For this reason,it is necessary to further study the composite operation process,composite connection effect,durability and the detection and evaluation method of composite performance.To solve these problems,this paper makes a systematic study on the joints from the aspects of raw material testing,heat shrinkable belt connection technology,combined connection specimen performance test and full-size joint test,etc.Based on the research project of steel reinforced spirally wound PE drainage pipe connection joint managed by Sinohydro Bureau 7 CO.,LTD.The main contents and results are as follows:(1)The basic performance test of the PE joint material was carried out.On this basis,the relationship between the flame heights of the heating gun,the running speed of the heating gun and the temperature of the heat shrink tape were determined.Besides,the relationship of temperature and bonding Strength were determined.Heating process parameters of heat shrinkable tape connection were put forward assording to heating flame height,gun walking speed,with suitable temperature and thermal paste bond strength.The heating flame height at about 15cm is appropriate,the heating flame walking speed from 10cm/s to 12.5cm/s is appropriate,the control temperature in the 110 ??120 ? is better.(2)The experimental results show that the tensile strength of the joint bonded specimen is higher than that of the single joint specimen.The combined joint does not immediately destroy after the fracture of hot melt extrusion welding,heat shrinkable belt through plastic deformation can still provide about 4MPa to the specimen strength,And before the destruction will produce a more substantial deformation.Moreover,whether the hot melt extrusion welding alone or composite connection,the weld width of 4?6mm reached the highest intensity.(3)Hot melt and heat shrink tape composite connection of the tensile properties and elongation at break to meet the requirements.After the watertightness tests of single hot melt extrusion welding and hot melt extrusion welding with heat shrinkable belt connection specimens,there is no water seepage under the 0.4Mpa pressure of two kinds of joints.In addition,the hot melt extrusion welding is less affected by salt and alkali,but is sensitive to acid solution,and the strength decreases by 17.5%.(4)The composite joint is intact in the process during compression deformation,proving the reliability of the connection.During permanent compression set,the strain value of heat shrinkable belt and PE pipe is larger,while which is small in steel strip.And the strain value increase gradually from the position 30 degrees to of 90 degrees,the maximum strain appears on both sides of the joint.