CORE PRINCIPLES
What to establish first
- Pressure produces membrane stress in a cylindrical wall.
- Pipe inside diameter affects velocity and head loss.
- Code scope, material certification and joint efficiency control allowable design stress.
Pressure Vessels & Piping
Pressure containment, piping geometry and flow support calculations.
MODULE OVERVIEW
Pressure Vessels & Piping in practical engineering work.
Pressure vessels and piping must contain pressure while accommodating temperature, supports, joints, corrosion allowance and inspection. Hydraulic flow calculations do not replace code-based pressure design.
DESIGN CONCEPTS
Terms worth checking
- Hoop stress
- Design pressure
- Flow velocity
Common applications: Plant piping · Hydraulic lines · Low-pressure vessels and manifolds
KEY RELATIONSHIP
Thin-wall cylinder hoop stress
σh = pD/(2t)
- p — internal pressure
- D — internal diameter
- t — wall thickness
The thin-wall relationship is valid only when its geometry and loading assumptions are satisfied.
WORKED EXAMPLE
Known values → substitution → interpretation
- Known values
- p = 1 MPa; D = 100 mm; t = 5 mm
- Method
- σh = 1 × 100/(2 × 5)
- Interpretation
- The nominal hoop stress is 10 MPa before joint, corrosion, external pressure and code rules are considered.
KEY DESIGN CHECKS
Confirm the conditions behind the number
- Define the governing load case, duty cycle and required design life before using a simplified relation.
- Use compatible units and material data for the actual condition, temperature and manufacturing state.
- Compare the result with strength, stiffness, fatigue, safety, serviceability and applicable-code requirements.
COMMON ENGINEERING MISTAKES
Keep the model within its scope
- Applying thin-wall cylinder hoop stress outside the assumptions shown on this page.
- Using a nominal condition while a peak, alternating, transient or environmental case governs the design.
- Treating a calculated value as a final component selection without checking interfaces, tolerances and the current governing standard.
AVAILABLE CALCULATORS
Select a calculator
RELATED RESOURCE
Open Pipe Flow Velocity Calculator
Calculate average velocity from flow and inside diameter.
Open related resource →REFERENCES & LIMITATIONS
Use this content as a transparent starting point
ReferenceASME B31.3 Process Piping and ASME BPVC references; use the licensed current code in its intended scope.ScopeRelationships are presented for the assumptions stated on this page and linked tool.Design reviewCheck material condition, loads, environment and the applicable current code.SafetyResults are educational/preliminary and do not certify safety or compliance.
RELATED ENGINEERING