Use the following instructions and Reference Drawing when identifying INTERNAL FLANGES.The presence of internal flange(s) is indicated by a dash number added to the basic style designations 17 through 22 as follows:•-1 Internal flange one end•-2 Interior flange(s) not located at either end•-3 Internal flange at both endsNOTE: Combinations will indicate all applicable dash numbers (e.g., 17A-1; 17A-2; 17A-3;...)Method of determining left end for internally flanged items:1. Left end determined by outer configuration, except for Style 17.For Style 17 Drawings1.Left end for Style 17 determined as follows:a. Interior Flange at one (-1)b. Interior Flange not at end (-2) nearest endc. Interior Flanges at both ends (-3) either (1) Largest flange width (2) If equal widths, largest hole diameterd. Multiple interior flanges not located at ends follow positioning instructions under 1c. above.2. If 1D and 1C have different characteristics, 1D will be the corner which has the varying characteristic which is first listed as follows:•Chamfered•Smallest Depth•Smallest Angle•Smallest Radius3. If 1D and 1C are the same style corners, 1A will be the corner which is first listed as in 2. aboveFor Style 18 DrawingsThe thicker of the two flanges is the left end or when flanges are of equal thickness, the larger OD flange is the left end.Method of determining left end when flanges are identical:1. If 1D and 1C have different characteristics, 1D will be the corner which has the varying characteristic which is first listed as follows:•Chamfered•Smallest Depth•Smallest Angle•Smallest Radius2. If 1D and 1C are the same style corners, 1A will be the corner which is first listed as in l. above.3. When 1D, 1C, 1A and 1B are the same style corners, corner 1E will be determined by using the priorities in l. above.4. When 1D, 1C, 1A, 1B and 1E are the same style corner, corner 1G will be determined by using the priorities in l. aboveFor Style 21 DrawingsMethod of determining left end:1. When flange is not centrally located, the first end is that end nearest to flange.2. When flange is central, the left end is determined as follows: a. If 1D and 1C have different characteristics, 1D will be the corner which has the varying characteristic which is first listed as follows:•Chamfered•Smallest Depth•Smallest Angle•Smallest Radius•Corner Data Reply Not Applicable b. If 1D and 1C are the same style corners, 1A will be the corner which is the first listed as in 2.a. above