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