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[MW:15163] RE: 15146] RE: 15142] Problem about Positive material Identification(PMI)

By Materials & Welding
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.

Email-pgoswami@sympatico.ca,

pgoswami@quickclic.net

 

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

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

 

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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