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1881 views
03:47 Jun-04-2004

S S Ananthan

Consultant,
RAA Tech Solutions,
India,
Joined Jun 2000
36
NDT of oxidised root welds

Hello,

In RT of 9 % Cr 1 Mo welded tubes can we identify the root oxidation ? Has any one got the experience in the postive identification of the presence of oxidation ? Can it be identified by UT ?

Additioanlly has this oxidation any deleterious effect in the life of the weld ?

Any comments on this will be useful.

S S Ananthan


 
05:28 Jun-05-2004

Floyd Atkinson

NDT Inspector
American Inspection Society, Inc.,
USA,
Joined Jun 2004
10
Re: NDT of oxidised root welds ----------- Start Original Message -----------
: Hello,
: In RT of 9 % Cr 1 Mo welded tubes can we identify the root oxidation ? Has any one got the experience in the postive identification of the presence of oxidation ? Can it be identified by UT ?
: Additioanlly has this oxidation any deleterious effect in the life of the weld ?
: Any comments on this will be useful.
: S S Ananthan
------------ End Original Message ------------

I have prior PMI and RT experience and feel the oxidation varies to widely to utilize RT for evaluation of an errosive root to face welds.


First, your eyes do not deceive you. Red rust is red rust.Alternatively, a brushed non-contaminated surface sample could identify the root cause of the root deterioration.The random sample should be evaluated for chemical contaminants in controlled laboratory conditions. Remember, the water for circulation in the vessel may have had bromide added to it for heat transfer properties.

Possible causes:
1)This may bea materials dilution / cross contamination problem if it is red rust. Check out the welding fabrication of the welds.I had welders use a carbon steel contaminated power wheel wire brush to grind their welds. They were unknowningly cross contaminating their welds to carbon steel.Later their welds on the stainless steel vessels rusted in the rain.

2)If this problem is predominately throughout the welds, there may have been a welding wire chemical dilution problem during fabrication.Check the owners operators data package for that specific serial number vessel fabrication.Confirm the Welding procedure specification was adhered to during fabrication.The wire supplier and their materials test reports supplied by the vendor/fabricaton should be readily available for your evaluation.
The welds dilution may be evaluted by the PMI tests methods.However,the surface interface will have to be polished if accessible for the dry method PMI testing.


Optionally, Radiographic Testing as in RT will determine the density change in the welds profile as accessible.A step wedge is utilized for this testing evaluation using medical grade (Grade M) fine grain film.Be sure the geometric unsharpness standard is adhered to by your radiogapher. This means get a sharp image of the welds over the welds viewing areas on the film between the markers.Make sure the two "T" hole on the penny or all six wires are clearly visible on your RT film. This may require an RT tubed source since as it is thin walled tube to head plate and intermitent spacers welds as in boiler interfaces.

Further, Magnetic resonance testing may reveal other areas of trouble spots by professionals in those areas. This is called eddy current testing. If you want to go this method, I recommend Hellier and Associates. They train the eddy current operators.

Good luck in your search for the truth.


 
06:11 Jun-08-2004

S.V.Swamy

Engineering, - Material Testing Inspection & Quality Control
Retired from Nuclear Fuel Complex ,
India,
Joined Feb 2001
782
Re: NDT of oxidised root welds Dear Shri Ananathan,

Greetings. Are you talking of oxidation during welding (caused by inadequate shielding) or during service? It looks as if you are interested in detecting oxidation at the fabrication stage.

If the oxide deposits are really serious, they should be visible in RT, just like slag inclusions. UT may or may not detect them depending on the acoustic impedance mismatch. Best way is to create some oxidation and then try to detect the same.

Oxide at the root is like slag. So what will be the long term effect on service can be looked at from that aspect.

Best wishes.

Swamy

----------- Start Original Message -----------
: Hello,
: In RT of 9 % Cr 1 Mo welded tubes can we identify the root oxidation ? Has any one got the experience in the postive identification of the presence of oxidation ? Can it be identified by UT ?
: Additioanlly has this oxidation any deleterious effect in the life of the weld ?
: Any comments on this will be useful.
: S S Ananthan
------------ End Original Message ------------




 
01:25 Jun-14-2004
NAT
Re: NDT of oxidised root welds ----------- Start Original Message -----------
: Dear Shri Ananathan,
: Greetings. Are you talking of oxidation during welding (caused by inadequate shielding) or during service? It looks as if you are interested in detecting oxidation at the fabrication stage.
: If the oxide deposits are really serious, they should be visible in RT, just like slag inclusions. UT may or may not detect them depending on the acoustic impedance mismatch. Best way is to create some oxidation and then try to detect the same.
: Oxide at the root is like slag. So what will be the long term effect on service can be looked at from that aspect.
: Best wishes.
: Swamy
: : Hello,
: : In RT of 9 % Cr 1 Mo welded tubes can we identify the root oxidation ? Has any one got the experience in the postive identification of the presence of oxidation ? Can it be identified by UT ?
: : Additioanlly has this oxidation any deleterious effect in the life of the weld ?
: : Any comments on this will be useful.
: : SS Ananthan
------------ End Original Message ------------

Weld oxyidation is does not look like slag as slag is of darker density. Weld oxyidation is bit britter than the near by weld metal with cloudy ,sponge like apperance some times associated with small spatter like weld metal sticking to it.
When a molten weld is oxyidized itlosses its desired properties , weaks mechanical and chemical

The welds with oxyidation tested desturtively have not passed any root bend test in my experiance(WPS)

However as No code has particularly identifed it as repair so far.
it up to the manufacturer to decide, if possiable to repair it better repair it.




 
02:10 Jun-14-2004
Gary Woodside
Re: NDT of oxidised root welds One of the easiest ways to see root oxidation is to use a camera.----------- Start Original Message -----------
: : Dear Shri Ananathan,
: : Greetings. Are you talking of oxidation during welding (caused by inadequate shielding) or during service? It looks as if you are interested in detecting oxidation at the fabrication stage.
: : If the oxide deposits are really serious, they should be visible in RT, just like slag inclusions. UT may or may not detect them depending on the acoustic impedance mismatch. Best way is to create some oxidation and then try to detect the same.
: : Oxide at the root is like slag. So what will be the long term effect on service can be looked at from that aspect.
: : Best wishes.
: : Swamy
: : : Hello,
: : : In RT of 9 % Cr 1 Mo welded tubes can we identify the root oxidation ? Has any one got the experience in the postive identification of the presence of oxidation ? Can it be identified by UT ?
: : : Additioanlly has this oxidation any deleterious effect in the life of the weld ?
: : : Any comments on this will be useful.
: : : S S Ananthan
: Weld oxyidation is does not look like slag as slag is of darker density. Weld oxyidation is bit britter than the near by weld metal with cloudy ,sponge like apperance some times associated with small spatter like weld metal sticking to it.
: When a molten weld is oxyidized itlosses its desired properties , weaks mechanical and chemical
: The welds with oxyidation tested desturtively have not passed any root bend test in my experiance(WPS)
: However as No code has particularly identifed it as repair so far.
: it up to the manufacturer to decide, if possiable to repair it better repair it.
:
------------ End Original Message ------------




 


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