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Discussion Forums - The Hendrix Group
HomeHomeDiscussionsDiscussionsOil Refinery Co...Oil Refinery Co...Pin hole in 4"x300# SS347 cast gate valvePin hole in 4"x300# SS347 cast gate valve
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11/26/2010 9:00 AM
 
Dear Experts , In our CDU/VDU plant , pump discharge gate valve , being used in HVGO pumping service at 300 deg C , showed pin holes in the body within 02 week of operation. What could be the reasons and which AWS electrode should be used to repair . I am suspecting improper heat treatment . Regards, Inspector 2011
 
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11/27/2010 9:00 AM
 
Hi Inspector 2011, The material specification (ASTM A351-CF8C?) stipulates the requirements for weld repair. Just my two cents worth of opinion: the defect can't be caused by improper heat treatment. It may have been a casting defect (check for records of shell hydrotest) or may have been caused by chlorides in water used for hydrotesting after which the valve was not dried properly.
 
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11/29/2010 9:00 AM
 
Thank u so much for your inputs ,
 
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12/1/2010 9:00 AM
 
Inspector 2011 Pin hole in SS castings could be original casting problem. In such short two weeks service run, service related effects like chloride SCC will not come to cause a pin hole leak. Chloride SCC will arise after some continuous usage and at poor casting defect areas to start with. S.S casting pump body is easily repairable using AWS equivalent to S.S grade (S.S 304/S.S. 316 L or S.S. 317 or S.S 321 variety of casting chosen for your original pump body). Did you specify any specific heat treatment at the time of P.O to suspect heat treatment problem? Normally, cast pump bodies are delivered in either annealed or normalized conditions only. Your pin hole is mostly related to original casting defect than other effect for such a short service. If the pump body had been properly hydro tested or pneumatic tested at the time of acceptance you would have noted this before installation Hope this helps C.V.Srinivasan Nishi Engineers Pvt Ltd India Dec 2, 2010 E mail: nishi@vsnl.com >Dear Experts , >In our CDU/VDU plant , pump discharge gate valve , being >used in HVGO pumping service at 300 deg C , showed pin holes >in the body within 02 week of operation. >What could be the reasons and which AWS electrode should be >used to repair . >I am suspecting improper heat treatment . > >Regards, > >Inspector 2011
 
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HomeHomeDiscussionsDiscussionsOil Refinery Co...Oil Refinery Co...Pin hole in 4"x300# SS347 cast gate valvePin hole in 4"x300# SS347 cast gate valve


  

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