A spirally wound corrugated pipe of sheet steel or the like is provided with outwardly convex corrugations which are spaced apart, with {HEAD ~ a flat portion} of {TAIL ~ single wall thickness} between adjacent corrugations 
A spirally wound corrugated pipe of sheet steel or the like is provided with outwardly convex corrugations which are spaced apart , with { HEAD ~ a flat portion } of { TAIL ~ single wall thickness } between adjacent corrugations
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH