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