{"id":983,"date":"2019-01-21T21:47:53","date_gmt":"2019-01-21T21:47:53","guid":{"rendered":"http:\/\/johnbrear-plantintegrity.com\/?page_id=983"},"modified":"2019-01-21T23:20:36","modified_gmt":"2019-01-21T23:20:36","slug":"models-for-predicting-hydrogen-attack","status":"publish","type":"page","link":"https:\/\/johnbrear-plantintegrity.com\/?page_id=983","title":{"rendered":"Models for predicting hydrogen attack"},"content":{"rendered":"<figure id=\"attachment_986\" aria-describedby=\"caption-attachment-986\" style=\"width: 266px\" class=\"wp-caption alignright\"><img decoding=\"async\" src=\"http:\/\/johnbrear-plantintegrity.com\/wp-content\/uploads\/2019\/01\/Hydrogen-damage.jpg\" alt=\"\" width=\"266\" height=\"186\" class=\"size-full wp-image-986\" \/><figcaption id=\"caption-attachment-986\" class=\"wp-caption-text\">High temperature hydrogen damage<\/figcaption><\/figure>\r\n<p><strong>Component:<\/strong><\/p>\r\n<ul>\r\n    <li>Pressure parts, fabricated from low-alloy steels, operating in hydrogen service at elevated temperatures<\/li>\r\n<\/ul>\r\n<p><strong>Situation:<\/strong><\/p>\r\n<ul>\r\n    <li>The susceptibility of such components to hydrogen attack is currently determined by reference to the 'Nelson curves' (API RP541)<\/li>\r\n    <li>These material-specific curves provide a go \/ no-go criterion based on temperature and hydrogen partial pressure<\/li>\r\n    <li>For most materials they do not contain any time-dependence, and are thus subject to periodic revision based on accumulating service experience in the industry<\/li>\r\n<\/ul>\r\n<p><strong>Objective:<\/strong><\/p>\r\n<ul>\r\n    <li>To provide a secure basis for determining the susceptibility to hydrogen attack<\/li>\r\n<\/ul>\r\n<p><strong>Approach:<\/strong><\/p>\r\n<ul>\r\n    <li>Analysis of the current Nelson curves, and the underlying data where available, in terms of accepted models of solubility and diffusion<\/li>\r\n    <li>Calculation of theoretical curves based on solubility and diffusion models<\/li>\r\n<\/ul>\r\n<p><strong>Benefits:<\/strong><\/p>\r\n<ul>\r\n    <li>A significant step towards understanding the basis of the Nelson curves<\/li>\r\n    <li>A provisional theoretical form of the Nelson curves with time dependence included<\/li>\r\n    <li>A reasonable correlation between the model and recent service experience of failures under conditions below the current published limits<\/li>\r\n<\/ul>\r\n<figure id=\"attachment_990\" aria-describedby=\"caption-attachment-990\" style=\"width: 966px\" class=\"wp-caption alignright\"><img fetchpriority=\"high\" decoding=\"async\" src=\"http:\/\/johnbrear-plantintegrity.com\/wp-content\/uploads\/2019\/01\/Nelson-1CrMo.jpg\" alt=\"\" width=\"966\" height=\"593\" class=\"size-full wp-image-990\" srcset=\"https:\/\/johnbrear-plantintegrity.com\/wp-content\/uploads\/2019\/01\/Nelson-1CrMo.jpg 966w, https:\/\/johnbrear-plantintegrity.com\/wp-content\/uploads\/2019\/01\/Nelson-1CrMo-300x184.jpg 300w, https:\/\/johnbrear-plantintegrity.com\/wp-content\/uploads\/2019\/01\/Nelson-1CrMo-768x471.jpg 768w\" sizes=\"(max-width: 966px) 100vw, 966px\" \/><figcaption id=\"caption-attachment-990\" class=\"wp-caption-text\">Nelson curves for 1CrMo steel<\/figcaption><\/figure>\r\n<p><strong>Publication:<\/strong><\/p>\r\n<p>Brear, J.M. and Church, J.M.<br \/>\r\n\u201cTechnical basis for API Publication RP941 (Nelson Curves)\u201d<br \/>\r\nThird Int Conf \u2018Engineering Structural Integrity Assessment\u2019, Cambridge, September 1996<\/p>","protected":false},"excerpt":{"rendered":"<p>Component: Pressure parts, fabricated from low-alloy steels, operating in hydrogen service at elevated temperatures Situation: The susceptibility of such components to hydrogen attack is currently determined by reference to the &#8216;Nelson curves&#8217; (API RP541) These material-specific curves provide a go \/ no-go criterion based on temperature and hydrogen partial pressure For most materials they do &hellip; <a href=\"https:\/\/johnbrear-plantintegrity.com\/?page_id=983\" class=\"more-link\">Continue reading <span class=\"screen-reader-text\">Models for predicting hydrogen attack<\/span> <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":157,"menu_order":4,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-983","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/johnbrear-plantintegrity.com\/index.php?rest_route=\/wp\/v2\/pages\/983","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/johnbrear-plantintegrity.com\/index.php?rest_route=\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/johnbrear-plantintegrity.com\/index.php?rest_route=\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/johnbrear-plantintegrity.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/johnbrear-plantintegrity.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=983"}],"version-history":[{"count":5,"href":"https:\/\/johnbrear-plantintegrity.com\/index.php?rest_route=\/wp\/v2\/pages\/983\/revisions"}],"predecessor-version":[{"id":985,"href":"https:\/\/johnbrear-plantintegrity.com\/index.php?rest_route=\/wp\/v2\/pages\/983\/revisions\/985"}],"up":[{"embeddable":true,"href":"https:\/\/johnbrear-plantintegrity.com\/index.php?rest_route=\/wp\/v2\/pages\/157"}],"wp:attachment":[{"href":"https:\/\/johnbrear-plantintegrity.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=983"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}