The Development and Validation of Engineering Methods of Calculating the Stress State of Spiral Tubes Loaded by Internal Pressure

A simplified method of calculating stresses in spiral tubes under internal pressure was developed. It was shown that in most cases the coordinate lines on the middle surface of the tube could be approximated as lines of curvature. The membrane equilibrium equations in partial derivatives due to the helical symmetry were reduced to one ordinary differential equation for the membrane force acting along the helix. It transpired that the solution to the differential equation almost coincided with the result of the application of boiler formulas that used the normal radius of curvature of the helix. The engineering method was demonstrated on a spiral tube with a given ratio of sizes.

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