Cellulosic Electrode Usage Instead of Basic Electrode

[Demir Alp]

• Dear Sirs;

  I would like to get Your professional advisory regarding selection of the filler material in Piping Welding of the P:1 G:1 Pipe Materials.

  For a large variety of Thickness and Diameters i have written 3 different WPS by combination of GTAW + SMAW process with usage of ER 70S-6 (Root and Hot Passes using GTAW) and E7018 (for Fill passes and Cap using  SMAW process.)

  However Our construction dept , insists on usage of Cellulosic electrodes instead of basic electrodes for higher deposition rate.

  As QA/QC I am doubtful replacing 7018 with 7010 or any other cellulosic electrode because of their tendency for hydrogen induced cracking. I'd like to add in my previous project We used to have X70 pipes and our employer didn't allow us to use cellulosic elecrodes just because hydrogen induced cracking.

  Thus I would like  to get your professional opinion regarding this subject,

   Best Regards; 

  Demir

• 
  

[Perumal Govindan]

Hi

You can not replace the electrode, since SFA number, UTS & alloying element presence to meet the weld metal properties  and WPS (approved) for pipe welding.

Regards
PG

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[Demir Alp ILIKOBA]

Dear Sir;

I know i can't change 7018 to 7010 depending on same PQR thus i am also making preparation for a new PQR. So please take my question as application will be done on new PQR. Additonally i shall say their intention to use cellulosic electrodes on large pipes (i.e 96'').Your comments are appreciated.

Best Regards;

Demir

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[Kannayeram Gnanapandithan]

Since Hydrogen level ( Around 30 to 60 ppm), it is not recommended for multiple pass/higher thick material because we will end up HICC

THANKS & BEST REGARDS,

KG.PANDITHAN, IWE,  AWS-CWI, CSWIP 3.1,

CONSULTANT-WELDING & QUALITY

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[Ramdoss Ravindiren]

Dear all,

From production point of view, electrodes with  higher deposition rates are being considered. But when it comes to quality, hydrogen induced cracking to be considered, hence basic coated electrodes  are the best.

Still cellulose electrodes r being considered, have a control on preheat temp on pipe, if req as per code and baking of electrodes, to reduce the possibility of hydrogen.

Note: hydrogen in excess of 4ml / kg is prone to hydrogen induced cracking.

Regards,
Ram

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From: Demir Alp ILIKOBA
Sent: ‎17-‎10-‎2015 02:06 PM
To: material...@googlegroups.com
Subject: Re: [MW:23728] Cellulosic Electrode Usage Instead of Basic Electrode

Dear Sir;

I know i can't change 7018 to 7010 depending on same PQR thus i am also making preparation for a new PQR. So please take my question as application will be done on new PQR. Additonally i shall say their intention to use cellulosic electrodes on large pipes (i.e 96'').Your comments are appreciated.

Best Regards;

Demir

To view this discussion on the web visit https://groups.google.com/d/msgid/materials-welding/CACj12PB5oc77hCyd3YYn8ZKswWM4de%3D4O3n1%2BpBg7YG0UHq8ng%40mail.gmail.com.

[Demir Alp ILIKOBA]

Dear all ;

First of all thank You so much for Your most valuable replies ,Mr Gnanapandithan and Mr Rovinden and Mr Govindan.

Then please let me raise another question regarding our subject taking into account 7016 electrodes what would be Your commentary?

From the point of hydrogen content ,Exxx6 series are low hydrogen content electrodes besides low hydrogen its said deposition rates are higher than Exxx8 electrodes thus maybe it's better to advise Exxx6 electrodes instead of cellulosic electrodes?

Thanks again for your valuable thoughts and replies;

Best Regards;

Demir 

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[Alan Denney]

Just to state what may be obvious: you do not bake cellulosic electrodes, which would destroy their properties. It is only the basic coated electrodes which you bake, to drive off combined water in order to ensure the low hydrogen content of the weld deposit. This is not necessary if you are using basic electrodes straight from a vacuum pack – which is special packaging and not the normal sealed packets. Always check the manufacturer’s data sheets and recommendations, since how you handle different types of electrodes can be confusing.

 

Alan Denney

AKD Materials Consulting Ltd

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[Kannayeram Gnanapandithan]

Demir

          7018 is having more deposition efficiency compared to 7016 because iron powders are added in 7018.   one advantage in 7016 is very light slag and bead is very smooth not like 7015.   Exx15,16 and 18  all are low hydrogen electrodes only. Coating materials are different. It is not advisable to bake Cellulose electrodes,  Purpose of more hydrogen in cellulose is defeated 

THANKS & BEST REGARDS,

KG.PANDITHAN, IWE,  AWS-CWI, CSWIP 3.1,

CONSULTANT-WELDING & QUALITY

To view this discussion on the web visit https://groups.google.com/d/msgid/materials-welding/001001d10a68%24d4748e60%247d5dab20%24%40denney1.freeserve.co.uk.