Feb-2025

Using CRA barriers to avoid metal degradation in gas plants (TiA)

When faced with metal wastage, asset owners and operators have viable options available to them in addressing the corrosion mechanisms with a corrosion resistance alloy (CRA) barrier. The technique used to apply this CRA will mainly be determined by the shutdown time available to carry out the application.

Rohit Kardile
Integrated Global Services

Article Summary

This case study explores a critical asset integrity challenge faced by a major Qatar gas plant, where severe metal degradation threatened the operational efficiency and safety of mission-critical gas processing equipment.

Problem
The Qatar gas plant produces and supplies natural gas and other hydrocarbon products from the Qatar North Field. The company’s onshore plant is located on the Qatari coast off the Arabian Gulf at Ras Laffan, about 80 km from the capital, Doha. It has a total capacity of 2,600 MMSCFD of reservoir fluid. The plant operates gas processing equipment that was suffering from severe pitting of the carbon steel shell, exposed to process gas rich in H2S, and CO2.

Initially, there was some internal scepticism about the effectiveness of thermal spray technologies, citing previous poor performance in similar industrial environments. This scepticism is not uncommon in the industry, as highlighted by other case studies demonstrating how conventional low-velocity thermal spray can fail dramatically, resulting in significant long-term costs compared to high-velocity thermal spray (HVTS) technology.

Technological solution: Advanced HVTS
Traditional thermal spray technologies often failed due to inherent limitations: permeability, internal stress, and weak bond strengths. IGS overcame these challenges when developing HVTS through:
•    Supersonic particle atomisation (exceeding Mach 1).
•    Proprietary alloy composition modifications.
•    Advanced chemical and process controls to prevent oxide formation.
•    Precise surface preparation techniques.

The modified NiCrMoW alloy and HVTS process achieved corrosion performance comparable to premium wrought alloy plates, with adhesion strengths ranging from 30 to 60 MPa.

Corrosion challenges
In industrial environments such as at the Qatar gas plant, corrosion represents a significant economic threat. Maintenance-related issues can cause substantial production disruptions. In the oil and gas sector, corrosion mechanisms are complex, involving factors such as acid-gas ratios, contaminants, two-phase flow, and vessel design.

Solution
IGS has partnered with this Qatar company since 2011 and successfully prevented metal degradation in all its gas processing equipment, including acid gas removal (AGR) amine absorber columns, AGR amine stripper columns, fibre film contractors, flare knock-out (KO) drums, disulphide oil (DSO) gravity separators, and mercaptan vessels.

IGS provides a robust integrity solution in both very high and low PH exposure conditions. This approach has proven to be far superior to traditional thermal spray methods. While some contractors might offer cheaper, conventional solutions, the long-term performance demonstrates that such short-term savings can lead to substantial future expenses.

During the January 2023 inspection, years after the initial HVTS application, protected vessels were found to be in excellent condition. This mirrors findings from another gas plant where HVTS-treated columns remained undamaged after six years, while conventionally treated columns suffered extreme corrosion and wall thickness loss.

Conclusion
The decade-long partnership between IGS and the Qatar gas plant demonstrates the transformative potential of advanced corrosion mitigation technologies. When confronted with critical asset integrity challenges, traditional repair methods often fall short. HVTS technology offers a sophisticated solution that addresses the complex corrosion mechanisms inherent in demanding industrial environments.

Key takeaways include:
•    Proactive corrosion management can prevent millions in potential production losses.
•    Technological innovations like HVTS provide superior protection compared to conventional methods.
•    Rigorous engineering standards and quality control are crucial in developing reliable corrosion barrier solutions.

The success of this project underscores a critical insight: investing in advanced asset integrity technologies is not an expense but a strategic approach to maintaining operational excellence, safety, and long-term economic performance.
As these environments become increasingly challenging, innovative solutions like HVTS will play a pivotal role in extending equipment life, reducing maintenance costs, and ensuring reliable operations.

This short case study originally appeared in PTQ's Technology In Action Feature - Q1 2025 Issue

For more information: rohit.kardile@integratedglobal.com