Optimal Design Of Stainless Steel Pipes With Spiral Stiffener Used As Gas Drainage

The gas drainage technology is important to coal mine gas safety, gasresources utilization and environmental protection, and widely used in the coalmining enterprises. In addition, it is a complex and important work to lay the gasdrainage pipes. With the continuous revolution of drainage technology, gasdrainage pipes also have experienced rapid improvement including steel pipes,glass steel pipes, plastic pipes, skeleton reinforced plastic pipe and claddingspiral corrugated steel pipes. But these pipes have their own disadvantages.There are some basic requirements for gas pipeline such as lame retardant,antistatic, good plasticity, high strength, low cost, light weight, corrosionresistance and so on. In recent years, a new kind of gas drainage pipes, beingmade of stainless steel, has been widely used. This kind of pipe also meetsvarious requirements of gas drainage pipe properties.The method of adding stiffener and reducing the wall thickness is used todesign this stainless steel pipes. And this method is widely applied to somethin-walled structure. The production process of pipes is making stainless steelspiral curled and welding forming. Taking that into consideration, we use spiralstiffener. So the design of spiral stiffener structure and its effect on increasing the strength of the pipeline becomes a key issue to promote the use of the gaspipeline. This is the main content of this paper.This pipeline failure by buckling, so introduced some basic theory andresearch methods about the thin shell buckling. In the macroscopic perspectiveof the energy method theory, the work on the shell transforms into the strainenergy of the shell. The strain energy is high or low relate to the deformationsize of the shell. In the micro perspective of the theory of thin-walled componentstability, The balance state of stress determined by pure normal stress imposedon the pipe wall jump to new equilibrium state which is mainly up to bendingstress.We can utilize the theoretical formula to calculate the critical bucklingload of non stiffened cylindrical shell under various external pressure. Comparedwith reinforced shell, it can be regarded as a reference. The spiral stiffenermakes the shape of the shell original section difference. So does its moment ofinertia. Therefore the theoretical formula cannot be used to calculate the criticalbuckling load of shell. But we can turn to some finite element analysis softwarefor Buckling analysis and parameter optimization of irregular model.Developing different theoretical model for spiral reinforcement in differenttypes and length, using shell element to mesh the model, referring to the actualsituation to define constrained boundary and load, we can analyze the shells’instability characteristics from simple to complex gradually. First, we analyzethe buckling deformation under lateral (radial) pressure. Furthermore, buildingseveral pipe models make eigenvalue buckling analysis.Meanwhile nonlinear analysis of a node added initial defects (geometry, material) must be done.Finally, optimization of multiple variables to determine the minimum wallthickness parameters can be achieved. Second,making deformation analysis ofbuckling under axial pressure. Making use of different length and different typesof shell, through a multi-disciplinary cross comparison, to find out the wallthickness, length and the spiral stiffener’s effect on the buckling critical load. Inaddition, we analyze the shell buckling deformation under the lateral and axialload, drawing the lateral critical load and the axial load curve in different lengthshell.After the simulation analysis, we conclude that spiral stiffener can improvethe lateral buckling load (ring stiffness)3times. Moreover, the optimizationanalysis of shell diameter of219mm helps us confirming that thickness of0.6mm can meet the provisions of the safety coefficient; Spiral stiffener changesthe state of shell deformation, when the shell under axial load, the spiralstiffener can make its stability decreased.Axial critical load with the increase ofthe length gradually increases first and then decrease sharply, the maximumvalue is at the critical point of the whole model deformation and localdeformation. When the shells under axial and lateral load, the lateral critical loadvalue decreased slowly if the axial load in the security value, and a sharp declinein more than the security value.To make sure the axial load be controlled in thesafe range.