E316 SS plate - porosity issues

[mahen dran]

 

Hi,

 

I am mahendra from KSA.

 

using 316L oerilicon electrode over 316L plate ((Flange joints - thickness around 8 mm)),

which creates porosity issue sometimes here . WPS and PQR are followed properly and there are no significant variation.

The electrode supplier suggests to use it in rebake oven.

 

We knows low hyd. electrodes  which  are ending  with 5,6 and 8 are to be used  with oven.

Is it correct way or normal proceudeure to use the SS electrode in oven ?

What is the control parameter to eliminate the porosity issue after  welding (Especially in  SS plate)

 

mahendra.t

[GERING, Erwin]

Dear Mahandra,

 

To prevent moisture pick up please use vacuum packed stick electrodes.

Oerlikon has also 316L – stick electrode in vacuum packed packaging.

If you have carton box, you will have always this risk.

 

Of course redrying in oven is technically a good solution (mostly 1- 2 hours 300 -350 degr C) if you are not sure (carton box).

Better is vacpac. 

 

With kind regards,

Erwin GERING

[claes.g...@esab.se]

The most commonly used stainless welding electrode (MMA) is the rutile acidic type, E3XX-17 (E3XX-16) according to AWS A5.4. This type of electrode contains only a relative small amount of limestone, which gives off the shielding gas (CO2) when welding. If the coating is not very dry, the content of water vapour in the shielding gas becomes high and there will be a porosity problem. Basic stainless electrodes , E3XX-15, according ro AWS A5.4, contain much more limestone, which gives more CO2 shielding gas. They can stand much higher coating moisture without giving porosity. Another problem with the -17 types is that they tend to pick up moisture rather quickly in warm and moist climate. Keep such electrodes in heated quivers, warm holding ovens etc. Rebake them at a rather high temperature, up to 350 °C. These electrode coatings are less sensible to heat than mild steel low hydrogen electrodes, so they can be rebaked at high temperatures many times if necessary.
Basic stainless electrodes (-15) can be rebaked too. They should be rebaked at a lower temperature, up to 300 °C, should be enough, and they are probably more sensitive to repeated rebaking than the -17 types.

Best regards,

Claes Gillenius
Development Engineer, MMA. (Spec. stainless and non Fe-alloys)
Direct tel:  +46 (0)31 509315
Mobile +46 (0)707532012
Company                ESAB AB
Address                  Box 8004, 402 77  Gothenburg, Sweden
                                 Lindholmsallén 9
Company  reg number        556005-7738

mahen dran <cbema...@yahoo.com> Sent by: material...@googlegroups.com 2009-11-07 14:57 Please respond to material...@googlegroups.com

To material...@googlegroups.com cc Subject

[MW:3609] E316 SS plate - porosity issues

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[mahen dran]

Dear Erwin,

 

Thanks for your information. I tried with redrying oven with 1 hour soaking and  it gives good result.

Once again thanks for your effort

 

mahendra

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From: "GERING, Erwin" <Erwin....@airliquide.com>
To: material...@googlegroups.com
Sent: Mon, November 9, 2009 10:56:20 AM
Subject: [MW:3613] RE: 3609] E316 SS plate - porosity issues

[mahen dran]

Thanks for your detailed analysis.

 

we are using E316-17  and  E316-16 in our power plant project.

After using these electrodes with  quivers , we  are not facing this issue now.

 

Thanks for your support

 

mahendra

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From: "claes.g...@esab.se" <claes.g...@esab.se>
To: material...@googlegroups.com
Sent: Mon, November 9, 2009 12:02:36 PM
Subject: [MW:3615] Re: E316 SS plate - porosity issues