Temperature Allowable Stresses Pipes

Overview

Engineering reference data for Temperature Allowable Stresses Pipes in fluid mechanics.

Key Formulas

Reynolds Number

$Re = \frac{\rho v D}{\mu}$

Ratio of inertial to viscous forces — determines flow regime.

Bernoulli's Equation

$P + \frac{1}{2}\rho v^2 + \rho g h = \text{const}$

Conservation of energy for steady, inviscid, incompressible flow.

Continuity Equation

$A_1 v_1 = A_2 v_2$

Conservation of mass for incompressible flow.

Darcy-Weisbach

$\Delta P = f \frac{L}{D} \frac{\rho v^2}{2}$

Pressure drop due to friction in a pipe.

Variables

Symbol	Description	Unit
$Re$	Reynolds number	—
$\rho$	Fluid density	kg/m³
$v$	Flow velocity	m/s
$D$	Characteristic dimension	m
$\mu$	Dynamic viscosity	Pa·s
$P$	Pressure	Pa
$f$	Darcy friction factor	—

Pipe Specifications

Standard	Description
A 53	Pipe, Steel, Black and Hot-Dipped, Zinc Coated, Welded and Seamless
A 106	Seamless Carbon Steel Pipe for High-Temperature Service
A 135	Standard Specification for Electric-Resistance-Welded Steel Pipe
A 333	Seamless and Welded Steel Pipe for Low-Temperature Service
A 334	Seamless and Welded Carbon and Alloy-Steel Tubes for Low-Temperature Service
A 369	Standard Specification for Carbon and Ferritic Alloy Steel Forged and Bored Pipe for High-Temperature Service
API 5L	Line Pipe
A 335	Seamless Ferritic Alloy Steel Pipe for High-Temperature Service
A 269	Seamless and Welded Austenitic Stainless Steel Tubing for General Service
A 312	Seamless and Welded Austenitic Stainless Steel Pipe
A 358	Electric-Fusion-Welded Austenitic Chromium-Nickel Alloy Steel Pipe for High-Temperature Service

Unit Conversions

• $1 \text{ psi} = 6895 \text{ Pa}$
• $1000 \text{ psi} = 6.9 \text{ MPa}$
• Temperature conversion: $T_{°C} = \frac{5}{9} (T_{°F} - 32)$

Example: Convert 20,000 psi to MPa: $20,000 \text{ psi} \times 6895 \text{ Pa/psi} = 137,900,000 \text{ Pa} = 137.9 \text{ MPa} \approx 138 \text{ MPa}$

Allowable Stress per ASME B31.3

For ASME B31.3 Process Piping, the allowable stress is determined by: $\sigma_{allow} = \frac{S_t}{3}$ where $S_t$ is the tensile strength of the material at the operating temperature.

In contrast, ASME B31.1 Power Piping uses: $\sigma_{allow} = \frac{S_t}{3.5}$

B31.3 applies to piping systems in chemical and petroleum plants, refineries, and related facilities, covering fluids such as chemicals, hydrocarbons, gases, steam, and cryogens.

References

• Original Source