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Dynamic & Seismic Analysis
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Seismic & Vibration Piping Analysis
Dynamic load cases inside the CAESAR II model — earthquake, compressor pulsation, steam hammer, relief valve reaction, and equipment-induced vibration. Covered as part of a larger stress analysis or as stand-alone investigations.
- Domain A
Seismic piping analysis
Seismic analysis evaluates the ability of a piping system to withstand earthquake loading without loss of containment, support failure, or excessive piping damage. Several jurisdictions in Southeast Asia — Indonesia, the Philippines, and parts of Malaysia — impose seismic design requirements on plant piping through statutory code or owner specification.
How the seismic analysis is performed
- 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
- Domain B
Vibration & Dynamic Load Analysis
Evaluates the response of a piping system to non-seismic dynamic loads. Softstra builds dynamic load cases inside the same CAESAR II model used for the static analysis and applies API, ASME, and Energy Institute guidance for the specific dynamic source.
Dynamic Sources We Analyse
Compressor pulsation
Reciprocating and screw compressor discharge piping can experience significant pulsation. We apply API 618 and Energy Institute guidance for pulsation and vibration-induced fatigue, integrating vendor pulsation studies into the CAESAR II model.
Steam hammer and water hammer
Fast-acting valves, pump trips, and sudden flow reversals generate pressure waves that impose transient forces on piping. Time-history or equivalent static load cases for steam hammer events in power plant piping and water hammer in process piping.
Relief valve reaction force
Relief valve discharge generates a reaction force on the inlet piping. API RP 520 reaction force calculation, with verification against the transient load.
Slug flow and two-phase flow
Two-phase lines and riser bases can generate slug-induced vibration. We assess slug frequency and force against piping flexibility and support arrangement.
Equipment-induced vibration
Vibration transmitted from pumps, compressors, fans, and agitators into connected piping. Walkdown measurement combined with CAESAR II dynamic analysis identifies resonance risk.
Codes and References Applied
- ASME B31.3 — Process Piping (occasional load allowable)
- ASME B31.1 — Power Piping (occasional load allowable)
- API 618 — Reciprocating compressors, pulsation and vibration
- API RP 520 — Pressure-relieving device sizing and reaction force
- Energy Institute — Guidelines for Vibration Induced Fatigue Failure in Process Pipework
- NEMA SM-23 — Steam turbine nozzle loads (hammer-linked checks)
- Local seismic codes: MS EN 1998, SNI 1726, NSCP, DPT, ASCE 7
When to Commission
- New reciprocating compressor installation or change-out
- After an observed vibration incident or high-vibration alarm
- During revamp where fast-acting valves are being added
- Relief valve piping where transient reaction force may exceed static allowable
- Two-phase flow lines with suspected slug-induced loading
- Steam hammer investigation following a valve closure incident
- Process plants in seismic zones in Indonesia or the Philippines
- LNG, cryogenic, or offshore topside installations where seismic resilience is required
- Licensing or regulatory review requiring seismic qualification
Deliverables
- Dynamic and seismic load case CAESAR II results
- Stress and support response summary against allowable
- Support and anchor load table for seismic combination
- Bracing, restraint, or flexibility recommendations where required
- Vendor drawing review of new dynamic protection hardware
- Vendor drawing review of new dynamic protection hardware
- FAQs
Frequently Asked Questions
It depends on the project specification. Peninsular Malaysia has historically been treated as low-seismic, but East Malaysia and owner specs (especially LNG and critical process) may require seismic analysis per MS EN 1998 or ASCE 7. We confirm at scope-setting.
Yes. Both are load cases inside the same CAESAR II model. They are typically bundled into a critical-line analysis package rather than priced as separate projects unless scope demands it.
Full acoustic pulsation simulation is typically performed by the compressor vendor or a specialist acoustic consultancy. We integrate the pulsation results into the CAESAR II model. If no study exists, we advise scoping one.
Yes. Steam hammer events — valve closure, turbine trip — are routine scope on power plant analysis per ASME B31.1 occasional load rules.
Yes. Post-incident vibration investigations are a common stand-alone scope. We combine walkdown measurements with CAESAR II dynamic modelling to identify the underlying cause and recommend remediation.
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