Flange Leakage Analysis

START-PROF provides multiple methods for flange leakage evaluation:

Equivalent Pressure Method (Kellogg)

Conservative method converting axial force and bending moment into equivalent pressure:

F - Axial force on flange
M - Bending moment on flange
G - Effective gasket diameter
Prating - Allowable flange pressure from rating standards (ASME B16.5, EN 1092, GOST)

Test condition allowable pressure factors: ASME B31.1: 1.15, ASME B31.9: 1.2, ASME B31.3: 1.33, ASME B31.4: 1.15, ASME B31.5: 1.33, ASME B31.8: 1.11, EN 13480: 1.3

ASME VIII-1 Code Case 2901 / UG-44 Method

Less conservative method based on research by Dr. Warren Brown, adopted in ASME Code Case 2901 (2017).

Equivalent form:

Uses Fm factor from standard tables to increase allowable pressure.

DNV Method

Increases allowable pressure to hydrotest levels with 1.3 safety factor.

Equivalent form:

NCD-3658.3 Method

For high-strength bolting applications (allowable stress ≥ 138 MPa at 38°C).

User-defined C and Ab values in flange properties.
Sy values automatically retrieved from material database.

Analysis Properties

Property

Description

Axial Force

Calculated axial force N on flange (+ tension, - compression), excluding pressure thrust

Bending Moment

Resultant bending moment M on flange

Mx, My - Bending moments in perpendicular planes through pipe axis

Parameters

Design pressure for Peq methods
Bolt area, bolt circle diameter, and design pressure for NC 3658.3

Calculated

Equivalent pressure using selected method
For NC 3658.3:

Allowable

Allowable flange pressure
For NC 3658.3:

or

Menu Access

After analysis: Output > Flange Leakage