Re: change of drain pipeFrom: karsadi 
Date: Sunday, January 02, 2011
Time: 3:09:29 AM
Remote Name: 188.8.131.52
CommentsFor detail and clear comment, it better you mentions the required data of existing tank from existing Nameplate or datasheet of tank.
Yes you can do, to make the change of a drain pipe of the tank by completely removing the pipe and put a new one and please read more detail of ADDITION OR REPLACEMENT OF SHELL PENETRATIONS from API 653.