Pipe Stress Analysis Input
Template (Excel)

A pipe stress analysis input template is the structured register of every critical line on a project that requires formal piping flexibility analysis under ASME B31.3 (or B31.1, B31.4, B31.8). It captures the line tag, stress package number, criticality, design and operating conditions, material, geometry, loads (sustained, thermal, occasional including wind and seismic), and equipment nozzle allowables. Stress engineers use it as the input register for CAESAR II, Rohr 2, or AutoPIPE models. It is a mandatory detailed engineering deliverable and the audit trail for code compliance per ASME B31.3 Chapter II.

Required columns: line number cross-referenced to the line list, stress package number, criticality (Cat A high cycle or thermal, Cat B normal, Cat C non-critical per project criteria), isometric and P&ID references, PMS class, pipe material per ASTM, nominal size and schedule, corrosion allowance, mill tolerance, design pressure and temperature, operating temperatures across steady / upset / shutdown / steam-out, insulation density and thickness, fluid density operating and hydrotest, wind load per ASCE 7 or IS 875, seismic load per ASCE 7 or IS 1893 Zone, equipment nozzle allowables per API 610 / API 660 / NEMA SM23, anchor and support reference, spring hanger travel, PSV reaction force, and slug force for two-phase lines. See the ASME B31.3 standard reference.

Pathnovo, an engineering document intelligence platform, identifies stress-critical lines from the piping line list (using project criticality criteria: temperature thresholds, two-phase flow, large-diameter, hot tap, PSV downstream, equipment-connected) and extracts geometry and material from the corresponding piping isometrics. Design conditions, PMS material, and equipment nozzle data are auto-populated from the line list, PMS register, and equipment datasheets. Typical turnaround is 48 hours per stress package with 99.5% contractual accuracy on safety-critical fields. See the isometric extraction workflow.

ASME B31.3 paragraph 319.4.1 requires formal flexibility analysis for any piping system that exceeds the simplified criteria in 319.4.2 (the D-y / (L-U)^2 empirical formula). In practice, project criticality criteria typically include all lines above DN 100 with design temperature above 150 degC, any two-phase line, any line connected to a rotating equipment nozzle (pump, compressor, turbine), any PSV inlet or outlet, any hot-tap branch, any line in seismic Zone IV or V (per IS 1893), and any line in cyclic service above 7,000 cycles. Pathnovo applies the project criticality matrix to the line list to produce the stress input register. See the ASME B31.3 reference page.

CAESAR II (Hexagon, Houston), Rohr 2 (Sigma Ingenieurgesellschaft, Germany), and AutoPIPE (Bentley) are the three dominant pipe stress packages on EPC projects. They share the same physical input set: geometry from isometrics, material and code from PMS, design and operating conditions from the line list, loads from project loading basis, and nozzle allowables from equipment datasheets. The stress input template is software-agnostic; the software-specific model file (CAESAR II .C2, Rohr 2 .rxx, AutoPIPE .dat) is built by the stress engineer from the template register. Pathnovo exports the register in any of the three vendor formats.

On brownfield revamps the existing line list and as-built isometrics define the current stress envelope; the revamp scope (new tie-in lines, repurposed lines, changed operating conditions) defines incremental stress packages. Pathnovo extracts both as-built and revamp isometrics, then flags any line where revised design conditions exceed the original analysis (higher temperature, new occasional load, removed support). Typical Indian refinery and fertiliser revamp scopes (IOCL, HPCL, BPCL, GAIL, IFFCO, KRIBHCO) require re-analysis of every tie-in line plus any line within two anchor distances of the modification. The template includes a Revamp Scope column.

Downstream consumers: stress analysis output (sustained, expansion, occasional stress ratios) is recorded against each stress package, support load tables feed the civil and structural design for pipe rack and equipment foundation reactions, spring hanger schedules feed procurement (LISEGA, Witzenmann, Anvil), nozzle reactions feed the vendor for rotating equipment nozzle verification, and any code overstress triggers an isometric redesign (relocated support, loop addition, expansion joint). The stress input register is the single source of truth for the piping flexibility design audit. See the piping MTO extraction workflow and the piping class spec template.