The corrugation 22, {HEAD ~ concave arc portion} 32 and horizontal flat portion 24 are located sequentially along {TAIL ~ the axis} of pipe 20 
The corrugation 22 , { HEAD ~ concave arc portion } 32 and horizontal flat portion 24 are located sequentially along { TAIL ~ the axis } of pipe 20
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH