The upper half shell 24 is secured to {HEAD ~ the lower half shell} 22 by suitable means such as {TAIL ~ welding} 
The upper half shell 24 is secured to { HEAD ~ the lower half shell } 22 by suitable means such as { TAIL ~ welding }
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL