How are pressure-temperature ratings interpolated for ASME B16.5 and EN 1092-1 flanges?

Flange ratings are linearly interpolated between bracketed standard temperature points defined in ASME B16.5 Table 2 or DIN EN 1092-1 Table G.2.1 for the selected material group and pressure class.

What is the difference between operating bolt load (Wm1) and seating bolt load (Wm2)?

Wm1 is the minimum total bolt load required to maintain internal hydrostatic pressure and gasket compression during operation. Wm2 is the initial bolt load required to compress and seat the gasket at ambient assembly temperature without internal pressure.

Why is an ASME PCC-1 4-pass tightening sequence recommended?

A 4-pass star cross-pattern (30%, 60%, 100%, 100% check) ensures uniform gasket compression, prevents flange cocking, and avoids localized gasket crushing or thermal joint leaks.

ASME B16.5 / DIN EN 1092-1

ASME PCC-1 / Sec VIII App 2

Flange Rating & Bolt Torque Calculator

Verify ASME B16.5 & DIN EN 1092-1 pressure-temperature ratings, evaluate gasket seating stress factors ($m, y$) per ASME VIII-1 App 2, and compute ASME PCC-1 target stud tightening torques and 4-pass star schedules.

Flange Setup & Rating

Standard Preset Setup (Size / Class)

Material Group

Design Pt. P (bar)

Design Temp T (°C)

Gasket & Seating

Gasket Type & Factors (App. 2)

Gasket OD (mm)

Gasket ID (mm)

Bolt Materials

Stud Material Select

Target Torque Preload % Yield

50%

Flange Rating & Bolt Load Audit

Status: WARNING

Pressure Utilization (P / P_rated)85% (15.0 / 17.7 bar)

Operating Load (Wm1)

29,883 N

Seating Load (Wm2)

159,139 N

Pressure-Temperature De-rating Curve

Rating: 17.7 bar

Dynamic de-rating envelope comparing pressure classes in same standard. Operating point shown.

Hover over chart to inspect de-rating values along temperature scale

150Active

300

400

600

900

1500

2500

ASME PCC-1 Assembly Bolt Torque

Bolt tightening torque and star cross-tightening schedule per ASME PCC-1 guidelines.

Target Tightening Torque

125.7 N·m

Target Stud Preload52,780 N(50% of S_y)

PCC-1 4-Pass Tightening Schedule

Pass 1: 30% TorqueInitial seating cross pass

37.7 N·m

Pass 2: 60% TorqueIntermediate deforming cross pass

75.4 N·m

Pass 3: 100% TorqueFull tightening target cross pass

125.7 N·m

Pass 4: 100% CheckClockwise rotational checking pass

125.7 N·m

Tightening Pattern (4 Bolts)Numbers inside studs indicate recommended sequence order. Follow star sequence pattern for even seating.

Mathematical Models & Equations

Pressure-Temperature Rating Interpolation

P_{\text{rated}}(T) = P_{\text{lo}} + \frac{T - T_{\text{lo}}}{T_{\text{hi}} - T_{\text{lo}}} \cdot (P_{\text{hi}} - P_{\text{lo}})

Effective Gasket Seating Width (b)

b = \begin{cases} b_0, & \text{if } b_0 \le 6.35 \text{ mm} \\ 2.52 \sqrt{b_0}, & \text{if } b_0 > 6.35 \text{ mm} \end{cases}

Operating Bolt Load (Wm1)

W_{m1} = \frac{\pi}{4} G^2 P_{\text{design}} + 2 b \pi G m P_{\text{design}}

Seating Bolt Load (Wm2)

W_{m2} = \pi b G y

Target Bolt Tightening Torque (T)

T = K \cdot D \cdot F_b

Verification Calculation Log

1Pressure-Temperature Interpolation (P_rated)
- •Formula: P_{\text{rated}}(T) = P_{\text{lo}} + \frac{T - T_{\text{lo}}}{T_{\text{hi}} - T_{\text{lo}}} \cdot (P_{\text{hi}} - P_{\text{lo}})
- •Calculation: Operating at 100.00 °C. Sourced from material group 1.1, class 150.
- •Result: 17.70 bar
- •Note: Resulting utilization ratio: 0.8475 (84.7%)
- •Basic Gasket Seating Width (b₀)
- •Formula: b_0 = \frac{w}{2} = \frac{\text{OD} - \text{ID}}{4}
- •Calculation: (\text{OD} = 104.60 mm, \text{ID} = 60.50 mm) \rightarrow b_0 = \frac{104.60 - 60.50}{4}
- •Result: 11.0250 mm
- •Note: Calculated for facing type: Flat Ring
- •Effective Gasket Seating Width (b)
- •Formula: b = \begin{cases} b_0, & b_0 \le 6.35 \text{ mm} \\ 2.52 \sqrt{b_0}, & b_0 > 6.35 \text{ mm} \end{cases}
- •Calculation: b_0 > 6.35 mm \rightarrow b = 2.52 \cdot \sqrt{11.0250}
- •Result: 8.3674 mm
- •Note: Governs gasket contact seal and seating pressure.
- •Mean Gasket Contact Diameter (G)
- •Formula: G = \text{OD}_{\text{gasket}} - 2b
- •Calculation: G = 104.60 - 2 \cdot 8.3674
- •Result: 87.8652 mm
- •Note: Location of the virtual line of gasket seal reaction.
- •Operating Bolt Load (W_m₁)
- •Formula: W_{m1} = H + H_p = \frac{\pi}{4} G^2 P + 2b \pi G m P
- •Calculation: H = \frac{\pi}{4} \cdot 87.87^2 \cdot 1.5000 \text{ MPa}, \, H_p = 2 \cdot 8.3674 \cdot \pi \cdot 87.87 \cdot 3 \cdot 1.5000
- •Result: 29,883 N
- •Note: Hydrostatic Force H = 9,095 N, Gasket Maintenance Hp = 20,787 N
- •Seating Bolt Load (W_m₂)
- •Formula: W_{m2} = \pi b G y
- •Calculation: W_{m2} = \pi \cdot 8.3674 \cdot 87.87 \cdot 68.90 \text{ MPa}
- •Result: 159,139 N
- •Note: Initial bolt load required to seat gasket during assembly.
- •Minimum Required Bolt Area (A_m)
- •Formula: A_m = \max\left(\frac{W_{m1}}{S_b}, \frac{W_{m2}}{S_a}\right)
- •Calculation: A_{m1} = \frac{29,883}{172.40} = 173.3 mm², \, A_{m2} = \frac{159,139}{172.40} = 923.1 mm²
- •Result: 923.1 mm²
- •Note: Ab = 583.2 mm² provided by 4 bolts. Status: FAIL
- •Assembly Bolt Torque (T)
- •Formula: T = K \cdot D \cdot F_b
- •Calculation: T = 0.15 \cdot \frac{15.875}{1000} \cdot 52,780
- •Result: 125.7 N·m
- •Note: Based on target assembly preload of 50% of bolt yield strength (724.00 MPa).

Engineering DisclaimerEngineering calculations are provided for preliminary design and educational/reference purposes only. Users must verify all results according to applicable engineering standards, supplier data, manufacturing requirements, and professional engineering judgment.