Fitness-For-Service Analysis: Needs | Advantages | Highlights & More

by Ishita Kapoor on December 20, 2018


The main focus of Fitness-For-Service analysis is evaluating whether an equipment has downgraded in service and can carry on its intended function properly. 

This approach comprises in a rational decision process, enabling the engineer to decide whether the system can be controlled safely either as is, with reinforced inspection, after a requalification, or after a service or repair.


Fitness for service can be applied when:

  • The equipment design is not fully compliant with the relevant codes.
  • The equipment experienced an impact in service, during handling or in transit.
  • The non-destructive testing and equipment inspection have noticed defects beyond the admissible limits or those that have happened too early.
  • The equipment has never been examined, or only partly; the equipment acquired is old.


  • Feasibility of avoiding to remove the equipment from service prematurely which should only have to be returned at term.
  • Financial solution which is more economical than the replacing of the equipment.
  • Creating an administrative file to obtain a derogation.
  • Optimal utilization of the equipment based on precise assessment of its abilities.


IRC’s Fitness-for-Service (FFS) engineering assessment is a multi-disciplinary method for assessing mechanical components to decide if they are fit for continued service. 

The typical result of an FFS evaluation is a “go/no-go” decision on continued operation. An assessment of remaining life or examination intervals may also be part of such an evaluation, along with remediation of the degradation mechanism.

IRC’s methodology is based on the approach executed by a team of engineers who specialize in pressurized equipment technology, corrosion, material, structural analysis and inspection. The statutory requirements concerning the equipment are also taken care of.


  • Based on non-destructive testing, the Fitness for service methodology includes the following steps:
  • Equipment integrity and residual life linked to kinetics,
  • Guidance concerning the integrity due to future conditions.
  • Pressurized equipment (reactor, heat exchangers, columns, LPG tanks),
  • Offshore pipelines & risers.
  • Onshore pipelines,
  • Atmospheric storage tanks which includes cryogenic (LNG),
  • The methodology can be expanded to other equipment depending upon the circumstance.
  • The damage mechanisms correlate to the below non-restrictive list:
  • Stress Corrosion Cracking (SCC),
  • Metallurgical damages (embrittlement, intermediate phases)
  • Localised corrosion, whether general, under insulation or pitting
  • Fatigue (thermal or mechanical),
  • Creep,
  • Crack-like flaws


Here are the features of FFS and Remaining Life:

  1. Flaw Type Detection: This includes-
  • Corrosion
  • Brittle fracture
  • Fatigue
  • Crack-like flaws
  • Creep
  • Hydrogen embrittlement
  • Stress corrosion cracking
  • Dents and shell deformations
  • High-temperature hydrogen attack

2. Fitness for Service Application: This includes-

  • Fired heaters
  • High-energy piping
  • Turbines
  • Pipelines
  • Power lines
  • Headers
  • Pressure vessels
  • Storage tanks

3. Advanced Creep Testing: Remaining Life Assessment Based on Creep Testing – IRC’s advanced creep testing service includes reliable and accurate life assessment of components prone to creep damage. This facility provides a higher level of accuracy when it comes to life assessment techniques based on actual creep property of components. Creep testing assessments lets operators optimize operating conditions, decide effective inspection intervals and extend component life.

IRC has carried out numerous projects for FFS on Piping operating at Temperature of Creep.

4. Pipeline Defect Assessment: IRC has a unique combination of major industry fracture mechanics expertise with integrity management experience, data analysis and software.

Our integrity management tools help us to support our clients with consulting and software solutions whether they are handling anomaly response plans, fitness-for-service assessments strain analysis of dents and deformations or failure analysis.

About IRC Engineering Pvt. Ltd.

IRC is one of the fastest growing Testing and Inspection company in India. We at IRC provide Non-Destructive Testing, Destructive Testing, Advanced NDT, Third Party Inspection, Condenser Testing, Electrical Testing, Residual Life Assessment of Power Plant, O&M Services, Fitness For Service, Civil Testing and Training services.

read more
Ishita KapoorFitness-For-Service Analysis: Needs | Advantages | Highlights & More

How The Oxide Layer Deposit Is Formed In Various Heat Transfer Regions?

by ircengg on June 4, 2015

Oxide of high porosity (>50%) is found to deposit in drum as well as once-through boilers under both low and high oxygen water chemistry conditions. The deposition rate is approx. proportional to the concentration of particulate iron oxide and the square of the heat flux. The best approximation to the real situation is given by

D = k q2 c t

D = amount of magnetite deposited (kg/m2)
q = the heat flux (W/m2)
c = concentration of iron in water (kg/m3)
t = time (hour)
k = constant ( approx. 5 X 10-13 / W2 m2/s

In a wick boiling mechanism, salts dissolved in the boiler water can be concentrated by factors > 104 as shown in the figure below.

Generally, the protective magnetite scale thickness is 10-15 microns in the waterwall tube. When the corrosion rate increases due to upset of water chemistry parameters in boiler, (due to salt ingress and concentration), the deposit formation also increases due to corrosion of metal and precipitation of contaminants whose water solubility decreases at higher temperature on the evaporator tube surface. To maintain the pH in boiler water, in case of reduction of pH due to salt ingress, addition of more Tri Sodium Phosphate (TSP) is required. In this process, at some places on the internal surface of waterwall tubes, deposit thickness increases and the protective iron oxide scale becomes non protective and porous in nature. Porous, insulating types of deposits allow boiler water to diffuse into the deposit where the water becomes trapped and boils.

The boiling of deposit in entrapped water produces relatively pure steam which tends to diffuse out of the deposit, leaving behind super heated non-boiling equilibrium solution of caustic, which is responsible for caustic corrosion or acidic solution, which is responsible of hydrogen damage in waterwall tubes as discussed below.

IRC is regularly carrying out such studies to find out the reason of the failures and are also giving remedial actions to prevent it, if required we can also carry out chemical cleaning of boiler.
IRC is a service provider having expertise in ndt, residual life assessment, fitness for service, advanced ndt, failure investigation, chemical cleaning, certification of storage tanks as per chief controller of explosives guidelines , consultancy for boiler water chemistry and training

read more
ircenggHow The Oxide Layer Deposit Is Formed In Various Heat Transfer Regions?