Menu
Search
Filters
Close
Menu

A Fracture Mechanics Approach To Characterizing Hydrogen Embrittlement Of Fasteners

Picture for A Fracture Mechanics Approach To Characterizing Hydrogen Embrittlement Of Fasteners
Available for download

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
$0.00
$20.00
$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.

Product tags
Also Purchased
Picture for Hydrogen in Steels: A Critical Review and Recommended Practices
Available for download

Hydrogen in Steels: A Critical Review and Recommended Practices

Product Number: 51317--9548-SG
ISBN: 9548 2017 CP
Author: Mark Sadowski
Publication Date: 2017
$20.00

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 On the Susceptibility of Precipitation Hardened Nickel Alloys to Hydrogen Assisted Cracking
Available for download

On the Susceptibility of Precipitation Hardened Nickel Alloys to Hydrogen Assisted Cracking

Product Number: 51319-12846-SG
Author: Roberto Morana
Publication Date: 2019
$20.00

Precipitation Hardened (PH) Nickel alloys have been widely used in the Oil &amp; Gas Industry for decades as these materials offer high strength and outstanding corrosion resistance in aggressive environments. They are commonly used in high-strength components in downhole wellhead subsea and Christmas tree equipment. However high profile failures of equipment have occurred including tubing hangers cross-overs and subsea bolts with alloys such as UNS N07718 UNS N07716 or UNS N07725. In all these cases the mechanism identified was Hydrogen Assisted Cracking (HAC) as the result of the interaction between atomic hydrogen adsorbed by the alloy and its microstructure.PH Nickel alloys are all subject to precipitation of secondary and tertiary phases which if processed improperly (particularly during hot working and heat treatment) may adversely affect the material properties required for the intended application. Despite the number of scientific and technical contributions produced over the last years the interaction between these complex microstructural features and atomic hydrogen is still not understood and is further complicated by variations in testing approaches used to simulate severe hydrogen charging conditions. The present paper provides insights on the HAC failure mechanism for API 6ACRA PH Nickel alloys comparing findings from numerous studies. In addition implications for currently adopted standards and emerging specifications are also presented and discussed.
Picture for Improving Hydrogen Embrittlement Resistance Of Precipitation Hardened Nickel-Alloys
Available for download

Improving Hydrogen Embrittlement Resistance Of Precipitation Hardened Nickel-Alloys

Product Number: 51321-16673-SG
Author: Luca Foroni, Carlo Malara
Publication Date: 2021
$20.00

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.(
Categories
Industry
Recently viewed
Popular tags
View all

Association for Materials Protection and Performance

© AMPP All Rights Reserved.
Membership Terms of Content Use
Contact Customer Support