🎛️ Flange Pressure-Temperature Rating
Get the maximum allowable working pressure (MAWP) for ASME B16.5 pipe flanges based on material group, pressure class, and design temperature.
Tools
📝 Configuration
P_max = P_150(T) × Class_Factor × Material_Factor
Gasket: m, y per ASME B16.20
📊 Results
Configure inputs and click Compute to view results.
📘 Methodology
ASME B16.5 Ratings
Pressure-temperature ratings define the maximum allowable working pressure at a given temperature for each class. The base table is for Class 150, Group 1.1 material, and higher classes are scaled by standardized factors (e.g., Class 300 = 2.63× Class 150).
Material Groups
Materials are grouped by composition and strength. Group 1.1 (carbon steel A105) is the reference. Austenitic stainless steels (Groups 2.1/2.2) have different high-temperature behavior. Material factors adjust the base rating accordingly.
Gasket Factors
ASME B16.20 defines gasket factor m (maintenance factor) and minimum seating stress y (psi). Higher m and y values indicate a tighter, more reliable seal but require greater bolt loads. Spiral wound (m=3.0) is the most common industrial gasket.
📘 Calculation Methodology: ASME B16.5 Pipe Flange Pressure-Temperature Ratings
Mathematical Model & Theory
ASME B16.5 specifies maximum allowable working pressures (MAWP) for forged steel pipe flanges across material groups (e.g. Group 1.1 Carbon Steel A105) and class ratings (150# to 2500#):
Assumptions
- Flange dimensions and bolt materials conform strictly to ASME B16.5 / B16.47.
- Absence of excessive external pipe bending moments and severe thermal shock.
Academic References
- ASME B16.5-2020: Pipe Flanges and Flanged Fittings: NPS 1/2 through NPS 24.
- Nayyar, M. L.: Piping Handbook, McGraw-Hill.
Worked Engineering Example
A Class 300 ASTM A105 carbon steel flange operates at design temperature $T = 250^\circ\text{C}$. Find maximum allowable pressure and required cold hydrotest pressure.
Step-by-step Solution:
1. Look up ASME B16.5 Table 2-1.1: At $38^\circ\text{C}$, $P_{rating} = 51.1\text{ bar}$ ($740\text{ psi}$). At $250^\circ\text{C}$, $P_{rating} = 41.9\text{ bar}$ ($608\text{ psi}$).
2. Factory hydrostatic test: $P_{test} = 1.5 \times 51.1 = 76.65\text{ bar}$ ($1112\text{ psi}$).
Final Result:
MAWP at $250^\circ\text{C}$ is $\mathbf{41.9\text{ bar}}$ ($\mathbf{608\text{ psi}}$); Hydrotest pressure is $\mathbf{76.7\text{ bar}}$.