Establishing Guidelines to Avoid CO/CO2 Cracking in CO2 Pipelines

DNV is leading a Joint Industry Program (JIP) aimed at establishing comprehensive guidelines for mitigating CO/CO2 cracking in CO2 pipelines.

The global shift towards achieving net-zero emissions by 2050 necessitates the development of robust Carbon Capture Utilization and Storage (CCUS) infrastructure. The transportation of captured CO₂ from source to storage is pivotal in achieving this goal. However, corrosion and running fracture pose significant challenges to CO₂ pipelines. Recent research has indicated that even small impurities like CO and H₂ can trigger environmentally assisted cracking in line pipe steels exposed to high-pressure CO₂. While work on the effects of low-pressure H₂ is underway, limited attention has been given to understanding the impact of CO cracking. This JIP focuses on defining limits for CO and other impurities and establishing qualification methods for line pipe steels and welds to prevent CO/CO₂ cracking.

Challenge

The primary challenge is to address the susceptibility of line pipe steels to CO/CO₂ cracking, especially in the presence of impurities like CO, O₂, NO₂, and varying condensate chemistries. This requires an in-depth understanding of the factors influencing cracking behavior, metallurgical limits, and the development of a robust qualification methodology.

Objective

The key objectives of the JIP are as follows:

1. Define limits on CO and oxidizers (O₂, NO₂) to prevent CO/CO₂ cracking
2. Identify metallurgical limits (yield strength/hardness) to mitigate CO/CO2 cracking
3. Develop a qualification test methodology to screen line pipe steels and welds for susceptibility to CO/CO₂ cracking.

Approach

The JIP's approach is based on comprehensive testing and analysis, divided into two main tasks:

Task 1: Establishing limits on impurities

• Conduct electrochemical tests in dense phase CO₂ to understand the effects of CO and oxidizers
• Perform SCC (Stress Corrosion Cracking) tests to assess crack growth rates in various environments
• Validate the results through long-term 4-point bend tests on different microstructures.

Task 2: Development of a qualification methodology

• Utilize OLI modeling and electrochemical testing to identify key species influencing CO/CO₂ cracking
• Conduct SCC tests to determine crack growth rates under specific environmental conditions
• Validate limits for CO and other impurities through 4-point bend tests on various microstructures.

Benefits

The JIP is expected to provide the following benefits to its members:

1. Establish environmental and metallurgical limits to prevent CO/CO₂ cracking in CO₂ pipeline applications
2. Develop a qualification methodology for line pipes to resist stress corrosion cracking in the presence of CO/CO₂ and impurities.

Project Details

Scope: The project encompasses electrochemical tests, thermodynamic modeling, crack growth rate tests, and 4-point bend tests.

Deliverables: The JIP will deliver impurity and metallurgical limits to prevent CO/CO₂ cracking and a qualification methodology for line pipe steels.

Cost and Schedule: It is expected the full scope of the JIP can be delivered at a cost of kUSD 750 with ten members participating (kUSD 75 per member). The JIP can be initiated with a minimum of five members for a reduced scope of kUSD 375 (kUSD 75 per member). It is planned to execute this JIP in a duration of 24 months.

In conclusion, the establishment of guidelines to avoid CO/CO₂ cracking in CO₂ pipelines is vital for the successful implementation of CCUS technologies. This JIP, led by DNV, aims to bridge critical knowledge gaps, define limits, and develop qualification methods to ensure the integrity of CO₂ pipelines, contributing significantly to the global effort to combat climate change.