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A Fracture Mechanics Approach To Characterizing Hydrogen Embrittlement Of Fasteners

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Materials properties that are used in specific oil and gas environments are de-rated due to the risks associated with hydrogen embrittlement cracking. In oil production environments the concern is for the onset of stress corrosion cracking (SCC), while in seawater environments the concern is for Hydrogen Induced Stress Cracking (HISC). Both are hydrogen embrittlement phenomena with the distinction being the source of hydrogen for each. In SSC the source of hydrogen is from the presence of H2S in the oil production fluids, and in HISC the source of hydrogen is from the dissociation of water from the cathodic protection system. This paper is focused on the latter phenomena and aims to characterize the susceptibility of carbon alloy steels as applied in fastener applications, in a seawater environment under cathodic protection.

Product Number: 51321-16798-SG
Author: Herman E. Amaya, Behrang Fahimi, Ramgopal Thodla
Publication Date: 2021
Industries: Coatings and Linings , Corrosion Monitoring and Control , Coatings
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$20.00

This paper elaborates on a method previously reported that characterized a materials susceptibility to hydrogen embrittlement in a seawater environment under CP by monitoring the crack growth rate of
ASTM E18201 pre-cracked CT specimens at various constant stress intensity (K-levels) and at varying cathodic protection potentials. For the fastener grade ASTM A320 L7 & L43 grade carbon alloy material the initial reported results showed that the material susceptibility to hydrogen embrittlement followed a pattern influenced by the yield strength level of the material, specifically that material susceptibility is distinguished by the response to varying CP potential & applied K levels. Intermediate
yield strength (< 930 MPa) for example, showed multiple K1EAC threshold responses; while known susceptible material with very high strength levels showed reduced threshold response and insensitivity to more positive CP potentials. The paper presents additional results from those previously reported covering the yield strength levels between 725 MPa (105ksi) and 964 MPa (140ksi) and highlighting the transition between nonsusceptibility
to susceptibility right about 939 MPa (135ksi) and close to the hardness limit of HRC 34 identified in API 20e. These results can be represented graphically and can serve to establish design operating limits for the materials in a seawater environment under CP.

This paper elaborates on a method previously reported that characterized a materials susceptibility to hydrogen embrittlement in a seawater environment under CP by monitoring the crack growth rate of
ASTM E18201 pre-cracked CT specimens at various constant stress intensity (K-levels) and at varying cathodic protection potentials. For the fastener grade ASTM A320 L7 & L43 grade carbon alloy material the initial reported results showed that the material susceptibility to hydrogen embrittlement followed a pattern influenced by the yield strength level of the material, specifically that material susceptibility is distinguished by the response to varying CP potential & applied K levels. Intermediate
yield strength (< 930 MPa) for example, showed multiple K1EAC threshold responses; while known susceptible material with very high strength levels showed reduced threshold response and insensitivity to more positive CP potentials. The paper presents additional results from those previously reported covering the yield strength levels between 725 MPa (105ksi) and 964 MPa (140ksi) and highlighting the transition between nonsusceptibility
to susceptibility right about 939 MPa (135ksi) and close to the hardness limit of HRC 34 identified in API 20e. These results can be represented graphically and can serve to establish design operating limits for the materials in a seawater environment under CP.

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Picture for Hydrogen Embrittlement of ASTM A320 L7 & L43 Grade Carbon Alloy Steel Bolts in Subsea Environments
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Hydrogen Embrittlement of ASTM A320 L7 & L43 Grade Carbon Alloy Steel Bolts in Subsea Environments

Product Number: 51319-12785-SG
Author: Herman Amaya
Publication Date: 2019
$20.00

This paper reports an approach towards studying the susceptibility of materials to hydrogen embrittlement of several yield strength levels of ASTM A320 L7 &amp; L43 grade carbon alloy material used for bolting . The test method used is based on ASTM E1820 using pre-cracked compact tension (CT) specimens in a seawater environment and under cathodic protection. The procedure has been to monitor the crack growth and the crack growth rate (CGR) at various constant stress intensity (K-levels) and at varying cathodic protection potentials. In this way these two parameters can be seen as representative of the susceptibility to embrittlement cracking of the materials at the specific stress intensity levels and as a function of the varying CP levels.The results indicate the strong effect that both stress intensity K-values and applied potential have on crack growth rates in environment and on the resulting susceptibility of the material to embrittlement. On the practical operational level the results also highlight the importance of actively monitoring and controlling cathodic protection (CP) potential levels as a means of increasing the allowable margin of error of the intersection between material quality design factors and the effect of the challenging environments of Oil &amp; Gas subsea drilling and production operations.
Picture for Hydrogen in Steels: A Critical Review and Recommended Practices
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Hydrogen in Steels: A Critical Review and Recommended Practices

Product Number: 51317--9548-SG
ISBN: 9548 2017 CP
Author: Mark Sadowski
Publication Date: 2017
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A summary of hydrogen bakeout history to remove hydrogen from a component. Existing recommendations regarding hydrogen bakeout in codes and standards. Results from an industry survey of energy producers. Proposed methodology for selecting bakeout parameters.

 

 
Picture for Improving Hydrogen Embrittlement Resistance Of Precipitation Hardened Nickel-Alloys
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Improving Hydrogen Embrittlement Resistance Of Precipitation Hardened Nickel-Alloys

Product Number: 51321-16673-SG
Author: Luca Foroni, Carlo Malara
Publication Date: 2021
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Precipitation hardened (PH) Ni-alloys are widely used in the oil and gas industry since they provide an excellent combination of corrosion resistance and mechanical strength. Their use in the manufacture of API1 6A pressure-containing and pressure-controlling components is subject to the stringent requirements of specification API Standard 6ACRA. However, matching the requirements of API Standard 6ACRA does not preclude susceptibility of some PH Ni-alloys to hydrogen embrittlement (HE) and this in some cases has led to premature and unexpected failures of components made from such
materials.(
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