RE: CORROSION ALLOWANCE FOR PRESSURE VESSELS

From: <Samuel>
Date: Thu Jun 13 2002 - 12:24:00 EDT

ASME DOES ADDRESS IT IN THE SCOPE OF NONMANDATORY SECTION. PLEASE REFER TO Appendix E Suggested Good Practice Regarding Corrosion Allowance, SECTION VIII, DIVISION 1, FOR DETAILS. AS A SCOPE OF GOOD (BEST) PRACTICE, YOU MAY FIND RELEVANT INSTRUCTION FROM MANY RESOURCES, STDS AND CODES, BOOKS, WEB-SITES, MAGZS, PROCEEDS, AND EVENTHOUGH NEWSPAPERS. IN MY KNOWLEDGE, THE BEST PRACTICE IS TO FIND THE HISTORIAN CORROSION DATA FOR THE SPECIFIED MATERIAL AT YOUR SERVICE CONDITIONS. AS A GENERAL RULE, YOU DON'T NEED TO DO ANY INSPECTION/TEST FOR MOST MATERIAL AS IT MAY BE AVAILABLE FROM OTHER RESOURCES. FOR EXAMPLE, YOU MAY FIND STANDARD CA FOR MOST HEAT EXCHANGER PARTS FROM RCB-1.5, TEMA, AND Appendix G of API 620 PROVIDES CONSIDERATIONS FOR SERVICE CONDITIONS THAT AFFECT THE SELECTION OD A CA FOR LOW PRESSURE VESSEL. HOWEVER, CA IS A MANNER USED FOR PREVENTING WEIGHT-LOSS CORROSION ONLY. AT THE SPECIFIED OPERATION CONDITION OF H2S, OTHER FORMS OF CORROSION OR MODES OF FAILURE SHOULD BE CONSIDERED IN THE DESIGN OF THE PRESSURE VESSEL, AND IT MIGHT BE MORE IMPORTANT THAN DETERMAINING CA. PLEASE REFER TO API RP55 AND NACE MR0175 FOR FURTHER GUIDELINES. REGARDS, SAMUEL LIU -----Original Message-----
From: Shahbaz Khan [mailto:shahbaz2@tullow.com.pk] Sent: Tuesday, June 11, 2002 10:25 PM
To: 'PipingDesign@yahoogroups.com'
Subject: [PipingDesign] CORROSION ALLOWANCE FOR PRESSURE VESSELS

We are in the process of specifiying some pressure vessels for natural gas. I am trying to locate some authentic material on the provision of an appropriate corrosion allowance. I have tried to locate the relevant information in the ASME code Section VIII but so far have failed to locate any categorical recommendation. Can anybody guide me regarding the working-out of an appropriate corrosion allowance for a pressure vessel viz-a-viz 1)construction material of the vessel 2)H2S & CO2 contents of the contained fluid 3)Chloride content in the fluid 4)pressure and temperature of the fluid and 5)Required life of the vessel. Is there any established industrial practice which can serve as a guide? I would be highly thankful for the requested guidance. Regards,
Shahbaz Khan

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[Non-text portions of this message have been removed] Received on Thu Jun 13 12:24:00 2002