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Re: [MW:23329] We are facing minor pore defects in CuNi 90/10

By Materials & Welding
 use Argon +helium mixture with peening

THANKS & BEST REGARDS,
KG.PANDITHAN, IWE,  AWS-CWI, CSWIP 3.1,
CONSULTANT-WELDING & QUALITY

On Tue, Oct 27, 2015 at 6:48 AM, pgoswami <pgoswami@quickclic.net> wrote:
Hi Muhammad,
 
Mr.. Gene Matsko, raised a very practical  problem related to source of gas porosity and  solution to the same. In spite of all good weld variables, weird issues like "Argon Leak" could cause such problems.Cupro Nickel  welds generally have less flowability than austenitic stainless steel weld metals and could generate "micro porosities" in the weld for the reasons as stated above. In addition the other resources  to minimize  porosities could be :-

  1. Sufficient amount of de-oxidizers , such as titanium in the filler wire.The advisable content around 0.5%,

  2. Cupro Nickel weld metal is  more sluggish than, say,  austenitic stainless steel. Weld preparations therefore need to be more open , such as an included angle of 70 to 80 deg to enable the welder to control and manipulate the weld pool. and to provide good shielding right up to the root.
  3. Cleanliness of weld preparations and filler wires , solvent cleaning  is generally advisable before welding . Weld preparations may need to have the tenacious oxide films removed by belt or disc sanding and should be thoroughly degreased with commercially available solvents.
  4. The use of high purity shielding gas. The use of Ar-H2 mixed gases reduces the risk of oxidation and leaves a brighter surface after welding compared with pure argon.
  5. Stainless steel wire brushes and stainless steel wire wool are also useful
  6. Last of all when GTAW is done in field, prevention of wind draft is essential.
 I hope enforcing some or all of the above checklists would help you to overcome the problem.
 
Thanks. 
 
Pradip Goswami, P.Eng,IWE
Welding & Metallurgical Engineer/Specialist
Ontario, Canada
 

From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com]
Sent: Saturday, July 25, 2015 4:49 PM
To: materials-welding@googlegroups.com
Subject: Re: [MW:23200] We are facing minor pore defects in CuNi 90/10

Many, many times very,very tiny 'pepper' like porosity is caused by an Argon leak in the connections, hose or torch. I have seen a TIG bead that looks very good on the surface and all of a sudden a very tiny gas pore will pop to the surface while welding. Upon grinding, removing the tiny pore, more pores will be discovered just under the surface of the 'good' bead just welded. I have seen welder go' crazy' just trying to figure it out. I will have the welder disconnect the electrical power to the TIG rig. Then I will have the welder fill a container with enough water so he can submerge the  hose & connections section by section. When the bubbles come up you can isolate and fix the leak. Make sure the welder completely drys the hose, connections & torch before starting to weld. You can also use "SNOOP' a leak detection liquid or just make some soapy water & brush it on.
Sincerely,
Gene Matsko



On Saturday, July 25, 2015 12:20 PM, José Juan Jiménez Alejandro <jjjimeneza@gmail.com> wrote:


you can use the camera technique, filling your tube with argon, argon more protection with your filler, ie, argon inside and out.

2015-07-25 6:14 GMT-05:00 Vanchinath S.A. <vanchinaths@gmail.com>:
You may try argon+1.5%Hydrogen as shielding gas.
On 25 Jul 2015 10:15, "Nazz A" <nazzimmm@gmail.com> wrote:
Sir  I am Muhammad.

we are working here in qatar under Qatar Petroleum.  We have to  complete the fire line systrm through Cu Ni.  We are using Tig welding and ising monel 67 CuNi filler wire. With goving back purging as Argon 99.99 % composition.

But still we arr facing the defects as porocity.  We already covered the area and clean the parent metals and filler wire. Using all of materials like cutting disk wire brush clits and everything is non ferrous.  Our present climate is summer here in Arabian dessert.

But in the Radiography,we cant controle the porocity here. Our all welders are wrll expetienced and well occupied. The poricity is always minor and when we cut out and checking its cant show.

Our acceptable criteria is lower than 0.6 mm.

I hope that you will give the right solution on our problem.

Yours regards...

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Skype: jjjimeneza
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