ASME B16.10-2009 pdf download – Face-to-Faceand End-to-End Dimensions of  Valves.
2.3.3 End-to-End. For those flanged valves where the gasket contact surfaces are not located at the extreme ends of the valve, the distance between the extreme ends is described as the end-to-end dimension and applies to flanged valves having the following nominal flange facing identifiers:
(a) ring joint
(b) large or small female
(c) large or small groove
2.4 Buttwelding End Valve Dimensions
For buttwelding end valves, the end-to-end dimension is the distance between the extreme ends (root faces) of the welding bevels (see Fig. 2).
Also see section 4.
2.5 Grooved End Valve Dimensions
The end-to-end dimension for grooved end valves is the distance between extreme ends.
2.6 Angle Valves
For flanged angle type valves (those in which the ends are at an angle of 90 deg to each other), the center-to- face dimension is the distance from the centerline of the port to the extreme end which is the gasket contact surface. For flanged angle type valves in which the gasket seating surface is not located at the extreme end and for angle type valves having buttwelding ends, the phrase center-to-end denotes the distance from the centerline of the port to the extreme end.
3 FACINGS OF FLANGED VALVES
Figure 1 shows facings for flanged ends.
Users are reminded that removing the 2 mm (0.06 in.) raised face will make the face-to-face dimension nonstandard.
3.1.3 7 mm (0.25 in.) Raised Face. Flanges for Class 600 and higher steel and alloy valves have 7 mm (0.25 in) raised faces, which are included in the face- to-face (or center-to-face) dimensions.
3.2 Other Standard Facings
Table 9 (Table 1-9) summarizes data on all flange facings and can be used with Tables I through 6 (Tables I-i through 1-6) in calculating face-to-face and end-to-end dimensions of flanged valves having standard facings other than those described in para. 3.1.
3.3 Ring Joint Facings
The X dimension given in Table 10 (Table 1-10), when added to the face-to-face dimension of a valve having raised face flanges in Tables I through 6 (Tables I-i through 1-6), establishes the end-to-end dimension for the valve having flanges with ring joint facings.
4 VARIATIONS OF LENGTh WITHIN A CLASS OF VALVES
4.1 Buttweldlng End Valves
Tables 1 through 6 (Tables I-I through 1-6) include end-to-end dimensions for valves having buttwelding ends. In many cases, the dimensions are different from those of face-to-face dimensions of flanged valves, as evidenced by the differences between dimensions A and B of the tables.
Also see para. 2.4.
4.1.1 Short Pattern. For pressure seal or flangeless bonnet valves having buttwelding ends in Class 600 and higher, the regular end-to-end dimensions shall be equal to the short pattern dimensions shown in Tables 3 through 6 (Tables 1-3 through 1-6). At the manufacturer’s option, the end-to-end dimensions of these valves may be the same as the face-to-face dimensions of raised face flanged valves.
4.1.2 Long Pattern. For flanged bonnet valves having buttwelding ends in Class 600 and higher, the regular end-to-end dimensions shall be equal to the face-to-face dimensions of raised face flanged valves shown in Tables 3 through 6 (Tables 1-3 through 1-6). At the manufacturer’s option, the end-to-end dimensions may be the same as the short pattern end-to-end dimensions.
4.2 Narrow, Wide, and Extra Wide Designations.