The flange includes {TAIL ~ a first portion} 12 of acetal material and a second portion 14 of {HEAD ~ an acid resistant material} provided directly over at least certain regions of the first portion 12 
The flange includes { TAIL ~ a first portion } 12 of acetal material and a second portion 14 of { HEAD ~ an acid resistant material } provided directly over at least certain regions of the first portion 12
OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH