The same problem happened to us in other material, if problems in weld metal then let you check this PMI test on the weld metal after surface clean by wire brush (try equivalent filler metal type) and/or remove some weld metal then you may get right result.
if failed the above method, in this worst case let us assume up to which level did not get result so remove weld metal like gauge/scoop and check by PMI, if you got the result, that much you have remove weld metal from joints & re-weld its better way Instead of cut out the full weld joint,
I hope this issue in surface level only,
Best regards,
Bala. R
+7 906 459 2882
--Mohamed,The results are surprising.D&H Secheron manufactures welding consumables of extremely good quality. I 'm going back to the days of late 1980s and early 1990s. Usually they stand behind their quality. Are you sure there's no mix up of welding consumables during the field or shop fabrication?You may run a test pad for all weld deposit conforming to ASME Sec-II Part C, SFA 5.28 any see how it differs to the consumable MTR. This could be done by XRF.If the consumable test pad conforms to Grade -91 ( ER 90S-B9 filler metal) then certainly it's mix up during welding.Another way is that scoop up some amount of weld metal and perform a wet/lab analysis and see what're the results.Let's know if it helps.Thanks.Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist
Ontario, Canada.
From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of mohamed jubair
Sent: Tuesday, August 28, 2012 3:25 AM
To: materials-welding@googlegroups.com
Subject: [MW:15142] Problem about Positive material Identification(PMI)
Dear all,
In our boiler one major problem occurred in Positive Material Identification(PMI) test [Spectrum test].
Description
Reheater finishing outlet(RHFO) coil
Material
T91
Size
ΓΈ 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
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 Cr Content.
Please go through the below readings of one RHFO joint.
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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