SAWH steel pipe in the construction industry have an indelible contribution, generally used as piling pipe, it is not only the main force of civil construction, the building of the modern hero. Urban renewal, environmental control and many other aspects are present in its presence. When the stress exceeds the elastic limit, if no increase in stress, the specimen continues steel or obvious plastic deformation, known as the yield of this phenomenon, the phenomenon arising from the minimum yield stress value is the yield point.
Withstand the internal pressure in the pipe, usually in the wall on the two main stress, stress δY radial and axial stress δX. Weld resultant stress δ = δY (l/4sin2α + cos2α) 1/2, where, α is the helix angle of the spiral weld pipe. Spiral weld pipe helix angle is generally 50-75 degrees, so the spiral weld resultant stress is 60-85% Longitudinal principal stress. At the same pressure, the same diameter spiral welded pipe wall thickness can be reduced compared Longitudinal.
SAWH steel pipe yield stress advantage, According to the above characteristics shows that:
A. SAWH steel pipe blast the weld suffered stress and the resultant stress is relatively small, blasting mouth is generally not originated in the spiral weld, its security Longitudinal high.
B. When present near the spiral weld defects parallel thereto, spiral weld force is smaller, so the risk of expansion as straight weld large.
C. Because of the radial stress is the maximum stress in the pipe, so the weld in vertical stress in this direction when under maximum load. Ie straight seam bear the load of the ring to weld to bear the load, the spiral in between.
