Compatibility Assessment of Natural Gas Pipeline Infrastructure Materials with Hydrogen, CO2, and Ammonia

 Compatibility Assessment of Natural Gas Pipeline Infrastructure Materials with Hydrogen, CO2, and Ammonia

It will be helpful to project higher authorities regarding future planning as per exhisting Gail infrastructure and Green molecules.

Main findings:Determined that NG pipelines are likely suitable for use with low blend levels of hydrogen, gaseous carbon dioxide and ammonia

Summary

• Relevance: Effort advances the transport of hydrogen, carbon dioxide and ammonia by identifying opportunities and challenges of repurposing NG pipeline infrastructure

• Approach:

– Conducted extensive literature data survey

– Examined over 100 components and materials in pipeline infrastructure

– Performance ranked based on known compatibilities

• Collaborations: HawaiiGas, Xcel Energy, CenterPoint Energy, MN Department of Commerce

• Technical Accomplishments:

– Identified and evaluated compatibility with over 100 infrastructure components and materials of construction

– Determined that NG pipelines are likely suitable for use with low blend levels of hydrogen, gaseous carbon dioxide and ammonia

– Compressor stations will not be compatible with neat hydrogen, sCO 2 and ammonia

– Identified key knowledge gaps

What we know about H2 compatibility

For Metals: H2 embrittlement of pipeline steels has been extensively studied.

– ASME B31.12 recommends maximum grade of X52 & API guidelines call for a maximum yield

strength of 827 MPa

– Studies suggest that NG blends containing up to 17% H 2 are suitable for use in existing NG pipelines

For Polymers: Much less studied, especially at conditions accompanying NG pipelines.

– Operational experience with NG-hydrogen blends indicates suitability with existing infrastructure

elastomers and plastics

– High swell observed for some elastomers under high pressures.

– Blister damage due to high decompression is a concern

Important knowledge gaps include:

– Many compressor station polymers not evaluated, especially at pipeline conditions

– Key information pertaining to the specific steel and alloy grades in compressor station components

is not available.

– The loads and stresses that are placed on stressed metal components (e.g. springs, diaphragms,

etc.) in compressor stations during operation are not available.

 

What we know about CO2 compatibility

For Metals: Extensive body of literature exploring CO2 corrosion of pipeline steels.

– Corrosion requires the presence of aqueous condensate (carbonic acid is formed)

– Studies have shown that H 2O, H2S, SOx and O2 can accelerate corrosion. Less well understood

are NOx contributions, which is a primary product of combustion. Note that NOx will form nitric

and/or nitrous acid with water.

For Polymers: Much less studied, especially at conditions accompanying NG pipelines.

– Known solvent for some polymers

– High swell observed for some elastomers

– Limited range of polymers studied. 

Important knowledge gaps include:

– Contribution of impurities (including NOx) to aqueous corrosion

– Corrosivity in liquid and gaseous CO 2 at conditions below the critical point

– Aluminum, stainless steels, zinc, brass, and other steel grades that are used extensively in

compressor/regulator stations

– Many compressor station polymers not evaluated, especially at pipeline conditions

What we know about ammonia compatibility

For Metals: Extensive body of literature on ammonia compatibility with metals. Ammonia is used

extensively in agricultural applications, as such storage and handling infrastructure is well established.

– Anhydrous ammonia is compatible with stainless steel grades, but low carbon, low-allow steels are susceptible to stress corrosion cracking if oxygen is present.

– Anhydrous ammonia is also suitable for use with copper-containing alloys. However, minor

amounts of water will enable stress corrosion cracking.

For Polymers: Extensive body of literature on ammonia compatibility with polymers

– Ammonia compatibility standards exist: ANSI B31.3 and ANSI K61.1

– Incompatibilities exist with fluorocarbons, polytetrafluoroethylene (PTFE), styrene butadienerubber (SBR).

– Suitability of ammonia with polyurethane and epichlorohydrin rubber is questionable

– Compatible polymers include some acrylonitrile butadiene rubbers (NBRs), nylons, and neoprene.

With best regards,

Dr. Amar Nath Giri