Re: [MW:11959] CAN RE-HYDRO IS POSSIBLE/FOR JOINTERS INSIDE THE PLANT---HYDRO PRESSURE BAR WILL CHANGE?????

Genearlly hydrotesting is done at 1.5 times the design pressure,due to this the material under goes microplastic deformation (@ weld toes deformation will be more) which helps to release some % of residual stress also , since  the material is allready undergone plastic deforamation its not good to make the material to undergo plastic deformation again and again ,which may lead to failure . so avoid hydrotesting more that one time.

On Wed, Jul 27, 2011 at 12:38 PM, sajidalam mohd. <engineer_makes_world@yahoo.co.in> wrote:

DEAR ALL               CAN WE DO RE-HYDRO FOR SHORTH LENGTH JOITED PIPED BEFORE RELEASE TO THE COATING PLANT?   MANUFACTURER IS SAYING THEY HAVE APPROVAL FROM CLIENTS.BUT WHEN I CHECKED THAT APPROVAL THAT IS ONLY FOR WELDING.NOTHING WRITTEN IN THAT APPROVAL ABOUT UT/X RAY/HYDRO ETC.TILL NOW THEY DIDN'T SUBMITTED ME APPROVED ITP.   BUT MANUFACTURER IS DOING 100% X RAY OF THAT JOINTED PORTION OF SHORTH LENGTH PIPES.BUT THEY ARE NOT READY TO DO RE HYDRO MY CLIENT IS SAYING FOR RE-HYDRO BEFORE RELEASE.   IT ALSO MENTIONED IN API 5 L 44TH ADITION CLAUSES 9.4.2. PAGE NO. 29 STATES THAT THE JOINTERS NEED NOT BE HYDROSTATICALLY TESTED, PROVIDED THAT THE PROTIONS OF PIPES USED IS MAKING THE JOINTERS WERE SUCCESSFULLY HYDROSTATICALLY TESTED PRIOR TO THE JOINING OPERATION.   WHILE DURING MANUFACTURING THESE PIPES 72"DIAMETER X 15.88MM WALL THICNESSX GARADE X65.WELDING BY SAW PROCESS.   THAT TIME WE REJECTED SO MANY PIPES DUE TO DEFECTS SO MANY PIPES BECOME SHORTH LENGTH AFTER REMOVAL THE DEFECTED PORTIONS.   NOW MANUFACTURER HAS APPROVAL FOR JOINT TWO SHORT LENGTH PIPES (DEFECTS FREE PORTION) AND THEY ARE DOING WELDING BY SAW/SMAW PROCESS.   WHEN MANUFACTURER WAS DOING WELDING BY SAW PROCESS AS PER CLIENT SPECIFICATION/API 5L HYDRO PRESSUR BAR WAS 74 BARS.   I AM ASKING BECAUSE MANUFACTURE IS DOING WELDING OF SHORTH LENGTH PIPES BY SMAW/SAW PROCESS (THAT IS CIRCUMFERRENTIAL WELD) IF NOW CLIENT IS REQUESTING FOR RE-HYDRO FOR TWO SHORT LENTH JOINTED PIPES.   IT IS POSSIBLE FOR RE HYDRO FOR CICUMFERENTIAL WELD FOR TWO SHORT LENGTH PIPES THAT IS WELDED BY SMAW/SAW PROCES.     AFTER CIRCUMFERENTIAL WELD BY SAW/SAMW PRESSURE BAR WILL CHANGE???????/BECAUSE CLIENT IS SAYING FOR RE-HYDRO AFTER JOINTED OF SHORTH LENGTH PIPES.   REGARDS MOHAMMAD SAZID ALAM INSPECTION ENGINEER KUWAIT 00966534077860

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With regards,
Sudhakar.k

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