Corrosion study revalidation and damage mechanism review reduce probability of failure and unexpected downtime

Client: Industrial Plant Services Limited
Location: Pacific Avenue Extension, Couva
Asset type: Ammonia Plant

Client Background:

Industrial Plant Services Limited (IPSL) is a privately owned independent organisation, providing a range of expert plant management services to clients in the petrochemical sector.

Lloyd's Register has provided numerous services to IPSL for a number of years, including asset integrity software solutions and integrity engineering services such as failure analysis and fitness for service assessments.

Business challenge for the customer:

IPSL requested support to conduct a Level 2 corrosion study revalidation and Damage Mechanism Review (DRM) on the CNC and N2000 ammonia plants. This involved multiple corrosion engineers to revalidate and identify any new potential damage mechanisms and identify corrosion rates for all fixed equipment items and associated piping, based on the relevant codes and industry experience. This helps maintain their RBMI database allowing IPSL to update criticality and inspections work plans.

This ensures that inspection plans are strategically developed so that the NDE contractors are inspecting for the correct damage mechanisms, using the correct inspection methods in the areas that are more susceptible to degradation, thereby allowing IPSL to focus valuable resources (time and money) in areas that are of high risk to their business operations.

How Lloyd's Register helped:

Our expert corrosion engineers conducted a Level 2 corrosion study and DRM for both Ammonia Plants.

This corrosion study involved collating data from LR's risk-based inspection and maintenance software solution - RBMI, Process Flow Diagrams (PFDs), Piping Instrumentation Diagrams (P&IDs), and inspection histories, as well as review and analysis of relevant plant data. As part of the corrosion study, we were able to report and educate on all the potential damage mechanisms and corrosion rates for all fixed equipment and piping for both ammonia facilities.

The information derived from the corrosion study and DMR was used to re-calculate criticality and produce updated Inspection Work Plans for each facility, meaning IPSL are now able to generate inspection work plans based on updated information contained within the RBMI software, thereby focusing on what is most critical to help improve reliability and cost efficiencies. The results from this study were then used to feed into the planning for their scheduled 2017 turnaround.

The final result was a successful corrosion study and final report which identified all possible damage mechanisms and estimated corrosion rates for all fixed equipment and piping included within RBMI.

Expertise applied:

  • Corrosion Engineering with specific emphasis on Ammonia Plants
  • Risk Based Inspection (RBI)
  • Corrosion Study/Asset Integrity/Inspection
  • Project Management


We removed potential damage mechanisms including Wet H2S, PTASCC, ClSCC and HTHA on approximately 17 equipment items, saving IPSL unnecessary inspection costs.

Appropriate planning and inspection can now also be carried out to determine the extent of the potential damage and take necessary steps to avoid failure and limit potential downtime, due to enhanced understanding of what and where the potential high risk areas are.

  • Reduced the chance of unexpected shutdowns, resulting in significant savings, as an unexpected shutdown can easily cost in excess of US$100,000 per day in loses.
  • Produced a “map” that identifies all damage mechanisms and corrosion rates for both plants on marked PFDs. These marked PFDs also highlighted all materials of construction and inspection data.
  • Identified a potential for Sigma Phase Embrittlement damage to the convection coils and associated piping. For which IPSL had experienced failures but was not 100% sure of what was the prevailing damage mechanism was. This can now assist IPSL in their mitigation measures.
  • Identified a potential for Ammonia Stress Corrosion Cracking for a number of equipment items that would have otherwise not have been identified, unless there was a failure. IPSL can now monitor for this potential damaged mechanism and take necessary mitigation measures to prevent failure.
  • Identified a potential for Nitriding to the Ammonia Synthesis Converter overhead outlet piping and shell of the Ammonia Converter Effluent Steam Generator exchanger, for which IPSL had concerns but was not sure of what was the prevailing damage mechanism. This will guide IPSL in their mitigation measures.
  • Identified several areas including dissimilar weld metal joints in critical equipment, mix points, areas prone to high thermal fatigue and specific piping circuits that could be highly susceptible to failure. IPSL would not have previously inspected for these and therefore had a high probability of failure. Now that these areas are identified, IPSL can allocate resources to facilitate inspection of these high risk areas in the upcoming 2017 turnaround.
  • Provided an estimated and calculated corrosion rates for equipment and piping. IPSL can now use this data to determine remaining life and therefor plan appropriately for future replacements or upgrades.


  • Time and money saved by enabling assets to be managed and inspected using the most effective approach
  • Focus can now be on conducting inspections where required
  • Reduced the inspection requirements (thus safety risk and costs) for the 2017 Turn-A-Round.


"The corrosion study is a fundamental part of IPSL's Mechanical Integrity program. The revalidation exercise is a key objective to ensure this crucial document remains relevant with regard to equipment damage mechanism susceptibilities and the information generated from this exercise is currently being used to update existing equipment inspection plans. The expert support provided by LR in overseeing and informing the study was instrumental achieving a thorough and comprehensive document which will bolster our Mechanical Integrity program."
Barry Nancoo, Condition Monitoring and Inspection Superintendent, IPSL.