{"id":578,"date":"2019-01-13T13:34:55","date_gmt":"2019-01-13T13:34:55","guid":{"rendered":"http:\/\/johnbrear-plantintegrity.com\/?page_id=578"},"modified":"2019-01-14T09:53:35","modified_gmt":"2019-01-14T09:53:35","slug":"type-iv-cracking-in-a-p91-header","status":"publish","type":"page","link":"https:\/\/johnbrear-plantintegrity.com\/?page_id=578","title":{"rendered":"Type IV cracking in a P91 header"},"content":{"rendered":"<figure id=\"attachment_584\" aria-describedby=\"caption-attachment-584\" style=\"width: 390px\" class=\"wp-caption alignright\"><img fetchpriority=\"high\" decoding=\"async\" src=\"http:\/\/johnbrear-plantintegrity.com\/wp-content\/uploads\/2019\/01\/endcap-0.jpg\" alt=\"\" width=\"390\" height=\"250\" class=\"size-full wp-image-584\" srcset=\"https:\/\/johnbrear-plantintegrity.com\/wp-content\/uploads\/2019\/01\/endcap-0.jpg 650w, https:\/\/johnbrear-plantintegrity.com\/wp-content\/uploads\/2019\/01\/endcap-0-300x192.jpg 300w\" sizes=\"(max-width: 390px) 100vw, 390px\" \/><figcaption id=\"caption-attachment-584\" class=\"wp-caption-text\">P91 header with flat plate end-cap<\/figcaption><\/figure>\r\n<p><strong>Component:<\/strong><\/p>\r\n<ul>\r\n    <li>Header, fabricated from P91, with welded-on, flat-plate end-caps<\/li>\r\n<\/ul>\r\n<p><strong>Problem: <\/strong><\/p>\r\n<ul>\r\n    <li>Explosive failure of an end-cap weld<\/li>\r\n<\/ul>\r\n<p><strong>Approach: <\/strong><\/p>\r\n<ul>\r\n    <li>Failure analysis, fracture mechanics assessment and design review<\/li>\r\n<\/ul>\r\n<p><strong>Results:<\/strong><\/p>\r\n<ul>\r\n    <li>Failure shown to result from Type IV cracking, initiating at a radius in the end-plate side of the weld preparation<\/li>\r\n    <li>NDE of other headers revealed a 1\/3 wall crack in another end-cap weld<\/li>\r\n    <li>Sectioning of another weld, that was NDE clear, revealed extensive Type IV cavitation damage<\/li>\r\n    <li>Fracture mechanics assessment indicated crack growth from initiation to failure in less than 10,000 hours, confirmed by oxide crack-dating. Thus adequate life could not be demonstrated<\/li>\r\n    <li>Design changes identified that would separate the weld HAZ from the stress concentration<\/li>\r\n<\/ul>\r\n<figure id=\"attachment_589\" aria-describedby=\"caption-attachment-589\" style=\"width: 800px\" class=\"wp-caption alignleft\"><img decoding=\"async\" src=\"http:\/\/johnbrear-plantintegrity.com\/wp-content\/uploads\/2019\/01\/endcaps.jpg\" alt=\"\" width=\"800\" height=\"200\" class=\"size-full wp-image-589\" \/><figcaption id=\"caption-attachment-589\" class=\"wp-caption-text\">End-caps showing progressive levels of cavitation and cracking<\/figcaption><\/figure>\r\n<figure id=\"attachment_586\" aria-describedby=\"caption-attachment-586\" style=\"width: 700px\" class=\"wp-caption alignleft\"><img decoding=\"async\" src=\"http:\/\/johnbrear-plantintegrity.com\/wp-content\/uploads\/2019\/01\/end-cap-cg5-1.gif\" alt=\"\" width=\"700\" height=\"363\" class=\"size-full wp-image-586\" \/><figcaption id=\"caption-attachment-586\" class=\"wp-caption-text\">Predicted and observed creep-crack growth rates in the end-cap weld<\/figcaption><\/figure>\r\n<h4><strong>Benefits:<\/strong><\/h4>\r\n<ul>\r\n    <li>Root cause of failure identified<\/li>\r\n    <li>Design changes to alleviate problem proposed<\/li>\r\n<\/ul>\r\n<p>Further research by the utility indicated a need for tighter controls on composition and heat treatment<br \/>\r\n<br \/>\r\n<strong>Published: <\/strong><\/p>\r\n<p>Brear, J.M,  Middleton, C.J., Munson, R and Viswanathan, R, <br \/>\r\n\u201cSuccessful management of Type IV cracking in advanced 9% and 12% chromium steels\u201d, <br \/>\r\nEPRI FRAC Conf \u20189Cr Materials, Fabrication and Joining Technologies\u2019  Myrtle Beach, SC, July 2001<\/p>\r\n<p>Brear, J.M., <br \/>\r\n\u201cA practical route for the life assessment of boiler pressure parts\u201d  <br \/>\r\nSMiRT 13 Post Conf  Seminar \u2018Intelligent Software Systems in Inspection and Life Management of Power and Process Plants\u2019, Paris, 25-27 August 1997<\/p>","protected":false},"excerpt":{"rendered":"<p>Component: Header, fabricated from P91, with welded-on, flat-plate end-caps Problem: Explosive failure of an end-cap weld Approach: Failure analysis, fracture mechanics assessment and design review Results: Failure shown to result from Type IV cracking, initiating at a radius in the end-plate side of the weld preparation NDE of other headers revealed a 1\/3 wall crack &hellip; <a href=\"https:\/\/johnbrear-plantintegrity.com\/?page_id=578\" class=\"more-link\">Continue reading <span class=\"screen-reader-text\">Type IV cracking in a P91 header<\/span> <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":114,"menu_order":4,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-578","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/johnbrear-plantintegrity.com\/index.php?rest_route=\/wp\/v2\/pages\/578","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=578"}],"version-history":[{"count":9,"href":"https:\/\/johnbrear-plantintegrity.com\/index.php?rest_route=\/wp\/v2\/pages\/578\/revisions"}],"predecessor-version":[{"id":581,"href":"https:\/\/johnbrear-plantintegrity.com\/index.php?rest_route=\/wp\/v2\/pages\/578\/revisions\/581"}],"up":[{"embeddable":true,"href":"https:\/\/johnbrear-plantintegrity.com\/index.php?rest_route=\/wp\/v2\/pages\/114"}],"wp:attachment":[{"href":"https:\/\/johnbrear-plantintegrity.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=578"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}