Dear Mr. Jubair,
-- Normally there is dilution of electrode chemistry in the weld. As a demonstration to your client, weld a pad of 200x200mm on T91 pipe with the same electrode and check chemistry at different heights from fusion line (FL+3, FL+8, etc). So you can accept this weld upto a defined dilution (say 10%).
--
2012/8/28 kulandaivel__subramani_ <subramak@batelco.com.bh>
Check with another PMI equipment preferably using XRF equipment.
On Tue, 28 Aug 2012 13:55:05 +0530
mohamed jubair <kmd.jubair@gmail.com> wrote:
Dear all,****
** **Identification(PMI) test [Spectrum test]. ****
In our boiler one major problem occurred in Positive
Material
** **
Description****
Reheater finishing outlet(RHFO) coil****
Material****
T91****
Size****
ø 63 x 4****
Process****
GTAW only****
Filler wire****
ER 90S B9****
Filler wire Manufacturer****
D & H Secheron****
Preheating °C****
185****
Rate of Heating °C****
100/hr****
Interpass temp °C****
190****
Post heating °C****
100****
PWHT °C****
750****
Soaking Time****
90 minutes****
****Content.**
Around 800 joints welded in the above approved procedure
only. Filler wire,
header stub, RHFO coil, weld metal undergone PMI test
separately and all
show positive material results as T91 except weld metal.
Weld metal shows
the Chromium content only as (4-7%){Reqd is 8-10.5%}.
We can't find how
it happened? Our Chinese consultant told to cut and
reweld all the joints.
But our contractor argued that we followed approved
procedure and used
approved vendor's consumable only. Please give a
solution. Here I have
attached one preheating cum PWHT chart of RHFO
joints(for 11 joints,5
thermocouples,1 recorder).All 800 joints are not checked
yet. Only 40
joints checked and all 40 weld metals shown low Crjoint.****
Please go through the below readings of one RHFO
*Description*
*Filler wire*
*Header stub*
*Weld metal*
*RHFO coil*
Alloy****
T91****
T91****
A-2****
T91****
Cr****
8.94****
8.34****
5.19****
8.68****
Mo****
0.96****
0.90****
0.93****
0.92****
V****
0.17****
0.17****
0.08****
0.19****
Ti****
0.07****
0.10****
0.04****
0.03****
Mn****
0.60****
0.40****
0.54****
0.63****
Fe****
87.81****
88.11****
90.86****
87.61****
Ni****
0.12****
0.33****
0.20****
0.38****
Cu****
0.02****
0.16****
0.20****
0.16****
Nb****
0.09****
0.08****
0.03****
0.04****
W****
0.15****
****
0.00****
****
** **
Waiting for your valuable suggestions.
Thanks & Regards
K Mohamed Jubair
--
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regards,
Harish.
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