The weakened zone 22, which is located in {TAIL ~ the centre} of tube section 20, is constituted by a thinner zone obtained by making an annular groove over {HEAD ~ the outer surface} of the section 
The weakened zone 22 , which is located in { TAIL ~ the centre } of tube section 20 , is constituted by a thinner zone obtained by making an annular groove over { HEAD ~ the outer surface } of the section
OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL 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 OTH OTH OTH