Spiral pipe stress analysis

Spiral pipe of the force is a very complicated situation. Spiral Pipe has affected transmission medium pressure, temperature effects were shed hoop stress generated axial stress; tube bearing capacity of the soil outside the pipe caused by different points along the length of the side asked the uniform settlement for bending sheet cows force; buried by soil pressure pipe above below the top soil by heavy, pipe weight, medium weight reaction force generated by such. Moreover, changes in the soil (plus landslide) external mechanical impact force, but also the pipe is compromised.

Spiral steel pipe inner force is clear. Calculation is simple. Spiral steel pipe outside force is not clear (large random factors), stress analysis is also more complicated. In recent years, although the next few pipeline workers in this area have been studied and published many articles, but still difficult as the design basis. The current practice is to pipe the force generated by the media for the design basis, and left a large degree of safety backup. In the safety in addition to considering the tube on the force generated by external causes, we should also consider the spiral steel pipe (including material and weld) that may arise outside the specified defects in the construction and handling, transportation, F Q, etc. Yim Sang to sodium pipe may damage (scratches, indenting, etc.). Degree of safety is based on the long-term practical experience to determine, issued
by the former Ministry of Petroleum Industry Pipeline design standards, due to internal pressure generated hoop stress control in the range of 0.72 yield limit due to the hoop stress and thermal stress generated when composed of axial stress over the yield limit stress control in 0.9 range. Security too large will result in an increase in capital base construction, low waste Road safety will spiral pipe accident increases. It should be noted that the incident is not caused due to the internal medium, or when the hoop stress occurs in overstressing old (because both have very low limit range), mostly due to an external force and the spiral steel pipe itself and the construction the deficiencies.