- A
flange O.D., in.

- A
_{b}
cross-sectional area of bolts, in.^{2}

- A
_{m}
total required cross-sectional area of bolts, in.^{2}

- a
nominal bolt diameter, in.

- B
flange I.D., in.

- B
_{1}
flange I.D., in.

- B
_{s}
bolt spacing, in.

- b
effective gasket width, in.

- b
_{o}
gasket seating width, in.

- C
bolt circle diameter, in.

- d
hub shape factor

- d
_{1}
bolt hole diameter, in.

- E, h
_{D}, h_{G}, h_{T}, R
radial distances, in.

- e
hub shape factor

- F
hub shape factor for integral-type flanges

- F
_{L}
hub shape factor for loose-type flanges

- f
hub stress correction factor for integral flanges

- G
diameter at gasket load reaction, in.

- g
_{o}
thickness of hub at small end, in.

- g
_{1}
thickness of hub at back of flange, in.

- H
hydrostatic end force, lb

- H
_{D}
hydrostatic end force on area inside of flange, lb

- H
_{G}
gasket load, operating, lb

- H
_{p}
total joint-contact surface compression load, lb

- H
_{T}
pressure force on flange face, lb

- h
hub length, in.

- h
_{o}
hub factor

- M
_{D}
moment due to H_{D}, in.-lb

- M
_{G}
moment due to H_{G}, in.-lb

- M
_{o}
total moment on flange, operating, in.-lb

- M′
_{o}
total moment on flange, seating

- M
_{T}
moment due to H_{T}, in.-lb

- m
gasket factor

- m
_{o}
unit load, operating, lb

- m
_{g}
unit load, gasket seating, lb

- N
width of gasket, in.

- n
number of bolts

*v*
Poisson's ratio, 0.3 for steel

- P
design pressure, psi

- S
_{a}
allowable stress, bolt, at ambient temperature, psi

- S
_{b}
allowable stress, bolt, at design temperature, psi

- S
_{fa}
allowable stress, flange, at ambient temperature, psi

- S
_{fo}
allowable stress, flange, at design temperature, psi

- S
_{H}
longitudinal hub stress, psi

- S
_{R}
radial stress in flange, psi

- S
_{T}
tangential stress in flange, psi

- T, U, Y, Z
K-factors (see Table 3-6)

- T
_{r}, U_{r}, Y_{r}
K-factors for reverse flanges

- t
flange thickness, in.

- t
_{n}
pipe wall thickness, in.

- V
hub shape factor for integral flanges

- V
_{L}
hub shape factor for loose flanges

- W
flange design bolt load, lb

- W
_{m1}
required bolt load, operating, lb

- W
_{m2}
required bolt load, gasket seating, lb

- w
width of raised face or gasket contact width, in. (See Table 3-5)

- y
gasket design seating stress, psi