(1) ANSIB16.5 is America flange system,150LB is the pressure rating of 150 pounds,the WN is welded flange,RF is said to face sealing surface of the flange for the process (called the petrochemical industry for convextable),18 "- 48" said flange size is 18 inch 48 inch.

(2) Q235 2281 PN10 DN700 15 64.33KGS chassis thickness:33.8explanation:

Q235 2281 is a steel,PN10 is the nominal pressure,because there is nounits,according to the formal interpretation should be nominal pressure is 10MPa,but Q235 is not allowed to use in the nominal pressure 10MPapipeline,comparing the actual explanation for 10bar,equivalent to theproject we usually say that the 10 kg,DN700 refers to the flangespecifications for the nominal diameter is DN700,15 is the number of 64.33kg refers to the flange,flange weight,S33.8 refers to the flange thickness 33.8mm.
There are possible explanations,if the nominal pressure flange is 10MPa,the S is welded flange neck high.My understanding is,Q235 steel is notused in the nominal pressure pipeline 10MPa.

(3) 300LBS STD 14''10 86KGS high neck pressure rating of 300 pounds,iswelded flange (high neck flange) 14 "flange specifications,14,weight is 86kg,because the code is not complete,can not make a full explanation.