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High Pressure Piping Inspection and Integrity Management

Experimental Stress Analysis - Strain Gauge Surveys

Challenges

Plant and asset managers are responsible for the continued operation of assets such as boilers, turbines, piping, transport, etc.  Unpredicted failures can result in costly down time, repairs and revenue loss.  Often design or operational modifications are required but without quantified stress data being available.  Experimental stress analysis can assist.  

Theoretical stress analysis (Finite Element Analysis, FEA) and known closed form solutions are used where load and support boundary conditions are clearly defined but this method is just that, theoretical. When boundary conditions are more complex involving dynamic factors, resonance, thermal transients, etc., the design theoretical solution is required to be more advanced and some loads may be unforeseen or even unpredictable.  We say, measure it, as strain gauges don’t lie.

Solutions

The solution strategy for repair requires quantified data to be measured.  Often actual loads experienced in service on assets are not known at the design stage or change due to operating demands leading to premature failures, such as metal fatigue, thermal fatigue, gross overload, to name a few.  These failure mechanisms are driven by several factors that always include stress.  Stress is calculated from measured strains as it is not a measurable quantity.  Put simply, design methods require the calculated stress to be less than the design strength of the component material.  We say prove it!

Strain gauges can be installed to any plant to obtain quantified strain data from which stresses can be calculated.  Strain gauges come in a wide variety of types and installation configurations.  Our proven calibrated and tested installation methods and data acquisition systems allow us to measure strains for a myriad of applications including:

  • Static strain (150 channels)
  • Dynamic strain (150 channels @ 1000 samples per second per strain element, faster for less channels)
  • High temperature strains (up to 750°C)
  • Residual strain

Stresses are calculated from the measured strains and used in the design or assessment process to determine the root cause and obtain a solution.

Strain gauges installation
HRL installs strain gauges to plant to obtain quantified strain data from which stresses can be calculated.

Applications

HRL Technology's stress analysts leverage solutions from experimental stress analyses (Strain gauge surveys) in the following manner:

  • To determine stresses experienced in actual service
  • To measure strains for fatigue curve material definition
  • To measure static and dynamic loads
  • To load balance boilers (by measuring strains in hanger rods)
  • To determine fatigue life
  • To prove design (AS1210-2010 Pressure vessels)
  • To obtain root cause of failure / failure analysis
  • To assess manufacturing methods - residual stress
  • For high end product research and development

Benefits

HRL Technology's stress analysts have been performing strain gauge surveys for over 50 years with a combined knowledge of over 100 years.  Much has been learnt in this time and we use this experience to provide proven experimental stress analysis techniques and measurements.  The benefits include:

  • Obtain quantified strain data
  • Calculated stresses allow asset managers to make informed decisions regarding plant operation or repair
  • Determine actual stresses experience in operation
  • Determine actual stresses due to operational changes
  • Prove a design is fit for its intended purpose
  • Life assessment and remaining life assessment for aged plant
  • Monitor the life of an asset
  • Safety
  • Large stock of strain gauges carried
  • Quick response to client needs
  • Savings on lost production
  • Mitigate further failures and insurance costs
  • Ensure correct operation
  • Defines design limits
  • Confidence in results (calibrated systems)
  • One stop shop (FEA, Failure analysis, etc.)
  • Real time display

Meet the expert

JAMES TAYLOR

Thirty years' experience in engineering consultancy of mining plant, rail track, rail passenger vehicles and rolling stock, transport vehicles, petrochemical and power plant. Specialising in pressure equipment (vessels and piping).  Company signatory for pressure vessel design verification. Fitness for purpose analysis including product integrity assessments. Australian Standards compliance testing.

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Contact our technical consultants on -
+61 3 9565 9888
or
info@hrl.com.au to get started today.

Our Certifications

NATA

NATA accredited AtS/NZS ISO 17025, AS/NZS ISO 17020NATA Accredited Laboratories number 561

ISO 9001 Quality Management

ISO 9001 Quality Management certified by BSI under certificate number FS605116.