- Service
Thermal Expansion Analysis
- Service
Thermal expansion pipe analysis.
Evaluates the movement of piping from ambient to operating temperature, verifies expansion stress range stays within the ASME allowable, and designs flexibility — loops, offsets, expansion legs, expansion joints — where direct routing cannot absorb the movement.
What the Analysis Covers
- Define seismic design basis — site class, peak ground acceleration, response spectrum
- Convert response spectrum to a CAESAR II load case input
- Apply seismic load case alongside sustained, thermal, and occasional cases per code combination rules
- Verify stress compliance against ASME B31.3 or B31.1 occasional load allowable
- Verify support and anchor loads against seismic-combination capacity
- Report findings, non-conformances, and recommended bracing or flexibility additions
High-temperature lines (above 150 °C) and cryogenic lines (below −29 °C) usually need formal flexibility design. Long straight runs between anchors, large-bore piping with limited routing freedom, and piping entering sensitive equipment nozzles are common cases where first-iteration routing doesn’t work.
Flexibility Methods We Apply
Expansion loops
Loops absorb movement in a three-sided configuration. Sized in CAESAR II, accounting for equipment movement at both ends, anchor placement, and guide spacing.
Offsets and expansion legs
Absorb movement by adding perpendicular piping runs. Used where space does not allow a full loop.
Expansion joints
Metal bellows, tied-universal, pressure-balanced, and hinged expansion joints. Expansion joint constants pulled from supplier data, not generic catalogue values.
Spring hanger sizing
Variable and constant-effort spring hangers absorb vertical movement. Travel margin verified against the full displacement range, not a reduced nominal value.
Liberal Stress Check (ASME B31.3)
When hot allowable stress (Sh) is greater than sustained loads (Sl). In a proper design system, the actual sustained stress is engineered to be safely below Sh, often hovering around 50%-70% of the allowable limit to prevent sagging or structural failure.
For most materials at design temperature, Sh is limited to two-thirds (67%) of the material’s yield strength. This liberal stress check allows you to take the “un-utilized” margin and add it directly to the allowable stress (Sa).
Sa = 1.25 Sc + 0.25 Sh – Standard allowable
Sa = 1.25 Sc + 0.25 Sh + (Sh – Sl) – Liberal allowable
Strict Compliance: This assessment is never applied blindly; it is executed strictly subject to formal client approval.
Deliverables
- Findings register with severity ranking across all domains in scope
- Root-cause narrative for any observed failure
- Recommended remediation per finding — code-cited
- Isometric markups showing overstress and nozzle non-conformance
- Support register and spring hanger travel table
- Flange joint summary with gasket and bolt recommendations
- Executive summary for project management and reviewers
Standards Applied
- ASME B31.3 — Process Piping (displacement stress range, allowable stress range calculation)
- ASME B31.1 — Power Piping (displacement stress and creep range on high-temperature piping)
- Owner-operator piping specifications where provided
When Commissioned Stand-alone
- Feasibility study for a plant revamp — flexibility check before detailed stress analysis
- Flexibility review of a proposed piping layout during front-end engineering
- Expansion joint specification for a new transfer line or heater outlet
- Retrofit review where plant operating temperature is being increased
- Investigation after an overstress event where the driver is thermal rather than pressure or weight
Deliverables
- Thermal stress range results per ASME B31.3 or B31.1
- Displacement table at key points (nozzles, anchors, guides)
- Flexibility recommendation — loops, offsets, expansion joints, spring hangers
- Expansion joint or spring hanger specification sheet where added
- Executive summary with findings and recommendations
- FAQs
Frequently Asked Questions
No. Lines that meet the non-critical criteria (small bore, low temperature, simple configuration) can be covered by the manual cantilever-beam calculation inside the main stress analysis service.
We specify expansion joints to the functional requirement — pressure, travel, angular and lateral movement, spring rate. Vendor-neutral during specification, but we can also supply through our product lines.
Equipment growth is taken from the vendor data sheet as a displacement load case at the nozzle. Fired heater tube-sheet and manifold movement is computed manually and fed into CAESAR II — a Softstra specialty.
For feasibility or front-end, yes. For final design, thermal expansion is normally a load case inside the broader stress analysis engagement.
Yes. Cryogenic service requires contraction load cases from ambient to operating, material-specific allowable stress values, and thermal-gradient-aware support design — all part of the scope where applicable.
- Get in touch
Start Your Thermal Expansion Analysis
We return with a recommended scope of work and quotation.