Aging Boiler or HRSG Life Assessment

Old Control Room Power Plant

The ageing of plant assets presents a real problem for owners and operators.  The viability of future operation can be called in to question when a boiler or HRSG begins experiencing failures, reducing availability and the bottom line.  The decision to run, re-rate, replace or retire is one that can only be answered by in-depth, cross-discipline analysis.  In particular, the gap between engineering and economic questions can be difficult to bridge.

Tetra aims to address both questions by first understanding the degree of degradation to the pressure parts:

  • Superheaters and Reheaters
  • Evaporators and Waterwalls
  • Drums
  • Economisers and Preheaters
  • Valves

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Fitness For Service

The boiler or HRSG is exposed to a variety of degradation mechanisms during operation and shutdown.  Regular inspection and good maintenance practice can minimise damage and degradation, but not eliminate it.  When damage is identified, what are your options? For pressure parts in critical service, where contract penalties apply, it may be desirable to delay repairs until the next planned outage or shutdown.

Tetra can provide a full range of services in the field of Fitness for Service assessments according to world recognised standards:

  • API 579-1 / ASME FFS-1
  • BS7910
  • Fitnet
  • B31.G
  • DNV-RP-F101
  • R5 / R6

 

Operating Data Review

A critical element of any remaining life assessment is the knowledge of the boiler's or HRSG's history.  The historical boiler temperature profile, as well as the past excursions or significant 'dynamic events', are used to give a better picture of degradation above the typical approach simply using operating hours and number of starts.  Many plants keep detailed records of historical data and calculate 'equivalent hours and starts' (see this Power Magazine article).  In modern plants, OEMs provide on-line creep and fatigue life assessments. 

Some plants have the data on record but haven't taken steps to calculate or assess the level of degradation incurred. Tetra can perform this service cost-effectively using the limited data available at the plant in combination with HRSG or Boiler Thermal Modelling to estimate process information where no sensors are available.

 

About Us

Established in 1989, Tetra Engineering has more than 25 years experience providing solutions to the power industry. We specialize in solutions for HRSGs, conventional boilers & steam-cycle balance of plant.

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Our Locations

Offices in: Connecticut, USA; Nice, France; Dubai, UAE.