Hydrogen-Induced Cracking

Hydrogen-induced cracking (HIC) is a form of material degradation and stress corrosion cracking. This can occur in metals and alloys in the presence of hydrogen.

The diffusion of atomic hydrogen typically causes HIC into the metal or alloy. It can react with various elements and form hydrogen atoms or molecules. These hydrogen atoms or molecules can then: 

• Migrate through the metal or alloy lattice
• Accumulate at areas of high stress or strain
• React with the metal to form hydrides

This process can lead to cracking and, ultimately, material failure.

HIC can occur in various industrial settings, including: 

• Oil and gas production
• Chemical processing
• Transportation

It is prevalent in environments with hydrogen, such as in sour gas or contact with hydrogen sulfide.

Several measures can be taken to prevent HIC, including: 

• Using materials that are resistant to HIC
• Applying coatings or barriers that can prevent the diffusion of hydrogen
• Implementing corrosion control and monitoring programs

Areas Susceptible to Hydrogen Induced Cracking

Hydrogen-induced cracking (HIC) can occur in metals and alloys in various industrial settings. They occur particularly in environments with hydrogen. Some of the areas that are particularly susceptible to HIC include:

Oil and Gas Production:

HIC is a common problem in the oil and gas industry, particularly in sour gas wells with hydrogen sulfide.

Chemical Processing: 

Chemical plants that use hydrogen as a feedstock or produce hydrogen as a byproduct can be susceptible to HIC.

Transportation: 

• Pipelines
• Tanks
• Other equipment 

Transporting hydrogen or hydrogen-containing substances can be susceptible to HIC.

Power Generation: 

Power plants that use hydrogen, such as hydrogen fuel cells, can be susceptible to HIC.

Aerospace:

Components that are exposed to high-stress environments and hydrogen can also be susceptible to HIC.

Identifying and addressing HIC risks in advance is crucial to prevent material degradation and potential failure of equipment or structures. This can be done through: 

• The use of materials that are resistant to HIC
• The implementation of corrosion control and monitoring programs 
• The application of coatings or barriers that can prevent the diffusion of hydrogen

Hydrogen-induced cracking (HIC) is a well-known phenomenon in the industry, particularly in the oil and gas sector. HIC can occur in a wide range of metals and alloys, including: 

• Carbon steel
• Low-alloy steel
• Stainless steel 

It can lead to material degradation and failure if not adequately addressed.

The incidence of HIC depends on several factors, including: 

• The environment
• The type of material
• The level of hydrogen present
• The level of stress on the material

For example, HIC is more likely to occur in environments where hydrogen is present than in environments where hydrogen is absent. Such as in sour gas wells.

The industry has developed various methods and techniques to prevent HIC, such as: 

• Selecting materials resistant to HIC
• Implementing corrosion control and monitoring programs
• Applying coatings or barriers that can prevent hydrogen diffusion 

While HIC can still occur, using these measures has helped reduce the incidence and severity of this type of material degradation.

Preventing Hydrogen Induced Cracking

Hydrogen-induced cracking can be prevented by implementing measures that reduce the risk of hydrogen entering the metal or alloy and using materials resistant to HIC. Here are some methods for preventing HIC:

Material Selection: 

Choosing materials resistant to HIC is the most effective way to prevent it. For example, certain types of alloys are less susceptible to HIC than carbon steels. Such as those containing molybdenum and chromium.

Corrosion Control: 

Using corrosion control and monitoring programs can help to identify and address HIC risks. This includes using inhibitors or cathodic protection to prevent corrosion and regular inspection to place any signs of HIC.

Coatings and Barriers: 

Applying coatings or barriers to the metal’s surface can prevent hydrogen diffusion into the metal. Examples of coatings or barriers include: 

• Epoxy coatings
• Rubber linings
• Corrosion-resistant alloys

Reducing Hydrogen Exposure: 

Reducing the exposure of the metal to hydrogen can also prevent HIC. This can be done by: 

• Controlling the temperature and pressure of the environment
• Purging the system with inert gases
• Using desiccants to remove moisture from the system

Implementing these measures makes it possible to prevent HIC. It ensures the safe and reliable operation of equipment and structures.

Inspecting for Hydrogen Induced Cracking

Inspection for hydrogen-induced cracking in metals and alloys can be done using visual inspection and non-destructive testing methods. Here are the general steps for inspecting for HIC:

Visual Inspection: 

The first step is to conduct a detailed visual inspection of the metal surface. Looking for any signs of cracking or blistering. HIC is often characterized by surface blistering, which can be visible to the naked eye.

Non-Destructive Testing:

Use non-destructive testing to further assess the damage’s extent when:

• A visual inspection reveals signs of HIC
• The material is known to be susceptible to HIC

NDT methods can include: 

• Ultrasonic testing
• Magnetic particle testing
• Eddy current testing
• X-ray
• Gamma-ray testing
• Other methods

Evaluation: 

After the NDT methods are complete, evaluate the results to determine the extent and severity of the HIC damage. The results of the NDT methods can determine if the material is still fit for service or if it needs to be repaired or replaced.

Repairs or Replacements: 

If HIC damage is detected, repairs or replacements may be necessary. This is to ensure the safe and reliable operation of the equipment or structure. The extent and type of repairs or replacements will depend on: 

• The severity of the HIC damage
• The specific material and equipment in question

It is essential to have regular inspections and monitoring in place. This is to identify any signs of HIC and address them before they lead to: 

• Material degradation
• The potential failure of equipment or structures

Non-Destructive Testing Methods

Non-destructive testing (NDT) methods can detect hydrogen-induced cracking (HIC) in metals and alloys. Some of the NDT methods commonly used for HIC detection include:

Ultrasonic Testing: 

Ultrasonic testing uses high-frequency sound waves to detect changes in the material properties. Properties such as cracks or voids, may indicate the presence of HIC.

Magnetic Particle Testing: 

Magnetic particle testing is a method that uses magnetic fields and iron particles to detect surface and subsurface cracks.

Eddy Current Testing: 

Eddy current testing uses electromagnetic induction to detect defects in conductive materials, including HIC.

X-Ray and Gamma-Ray Testing: 

X-ray and gamma-ray testing are imaging techniques that can detect HIC and other types of material degradation.

Visual Inspection: 

Visual inspection involves a detailed visual examination of the metal surface. It is often used with other NDT methods to detect HIC.

The choice of the NDT method will depend on several factors, including: 

• The type of material
• The location of the equipment or structure
• The extent of suspected HIC 

A combination of NDT methods may be used to ensure comprehensive detection of HIC.

The American Petroleum Institute (API) has several codes and standards for hydrogen-induced cracking (HIC) in the oil and gas industry. Here are some of the most relevant API codes for HIC:

API 579-1/ASME FFS-1 Fitness-for-Service: 

This code provides a method for assessing the fitness-for-service equipment that has experienced HIC damage.

API 5L Specification for Line Pipe: 

This includes requirements for manufacturing and testing line pipes that are resistant to HIC.

API RP 934-C Materials and Fabrication of Heavy Wall Pressure Vessels for High-Pressure Hydrogen Service Operating at or Below 825°F (441°C): 

This provides guidelines for selecting materials and fabrication of heavy wall pressure vessels for hydrogen service.

API RP 571 Damage Mechanisms Affecting Fixed Equipment in the Refining Industry: 

This provides information on various damage mechanisms that can affect equipment in the refining industry, including HIC.

API RP 934-A Materials and Fabrication of 2 1/4Cr-1Mo, 2 1/4Cr-1Mo-1/4V, 3Cr-1Mo, and 3Cr-1Mo-1/4V Steel Heavy Wall Pressure Vessels for High-temperature, High-pressure Hydrogen Service: 

This provides guidelines for the selection of materials and fabrication of heavy wall pressure vessels for high-temperature, high-pressure hydrogen service.

The National Association of Corrosion Engineers International (NACE) also has several standards and specifications for hydrogen-induced cracking (HIC) in the oil and gas industry. Here are some of the most relevant NACE specifications for HIC:

NACE MR0175/ISO 15156: 

This provides requirements for the selection and qualification of materials for use in H2S-containing environments, including requirements for HIC resistance.

NACE TM0284: 

This test method provides procedures for detecting HIC susceptibility in metals and alloys.

NACE SP0472: 

This provides guidelines for addressing HIC in pipelines and other oil and gas industry equipment.

NACE SP0102: 

This provides guidelines for addressing internal corrosion in pipelines and other oil and gas industry equipment, including HIC.