RE: [MW:12395] SMAW ELECTRODE FOR P91 MATERIAL

Hi Jose,

This issue was raised earlier in this forum. As per my knowledge base, majority of the SMAW electrodes for this material  conforms either to AWS SFA 5.5,E-9015-B9 or E-9016-B9 or E-9018-B9

As per industry experience greater success has been observed with the “-15” type electrode coatings than  other  varieties. Primary factors influencing this success are enhanced compositional control of tramp elements and better control of bead shape plus interbead tempering during welding.When using iron powder additions, deleterious tramp elements or elevated phosphorous can “come in the weld”.Thus E-9018-B9, electrodes  require very precise control (on the purity of Iron powder) to control the level of tramp elements/residuals in the weld. Chances are there that impact values of E-9018-B9 electrodes could be less technical requirements are  specified up front and agreed upon by the manufacturers and the end users.

One point of interest  would be specifying in the purchasing spec, ,  X-bar or X-Factor < 15, where ,X-bar = (10P + 5Sb + 4Sn + As) /100, where P, Sb, Sn, and As in ppm. X-Factor is a measure of temper embritltement, which highly influenced by the above tramp elements.

The attached data sheets of Kobelco and Metrode are in E-9015/9016 category ,while Bohler Thyssen have both -9015/9018-B9 type. The product of ADOR is in E-9018-B9 category.Many fabricators would prefer 9018-B9, possibly due to better deposition efficiency. However there could be problems as mentioned above.

If  impact test of weld metal is not a strict design requirements then E-9018-B9 may be used (provided it's purchased from known manufacturers, and the brand is proven, not just by AWS Equivalence). Having said that impact properties are not a requirement of ASME Sec-I or B-31.1 codes on P-91 steel but its advisable to have welding consumable procured with good notch toughness to have  balance of all types of mechanical properties and better service induced creep life, and creep/fatigue life (where thermal cycling is experienced).

Otherwise E-9015/9016-B9 should be the default choice.

I hope this would provide enough information on the above topic.

Thanks.

Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist & Consultant
Ontario,Canada.
Email-pgoswami@sympatico.ca,
pgoswami@quickclic.net

N.B:- If you get hold of API-938B- Use of 9Cr-1Mo-V (Grade 91) Steel in the Oil Refining Industry, read that at your leisure. Though this document is not mandatory for powerindustries , but many good design principles on P-91  are in this document.

Thanks.

-----Original Message-----
From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of naveen_sohal@yahoo.com
Sent: Wednesday, September 07, 2011 3:58 AM
To: materials-welding@googlegroups.com
Subject: Re: [MW:12356] SMAW ELECTRODE FOR P91 MATERIAL

Dear Friend,
E9018-B9 and E9016-B9 generally used for tubes or thin pipe welding without root run of GTAW.

Creep rupture data really makes the difference in addition to Mn+Ni %.

I think only 9015-B9 have the creep rupture data. You can use Thermanit Chromo 9V of Bohler Germany make.

Regards

Sent from BlackBerry® on Airtel

-----Original Message-----
From: JOSE SEBASTIAN <joseseban@gmail.com>
Sender: materials-welding@googlegroups.com
Date: Wed, 7 Sep 2011 00:41:27
To: Materials & Welding<materials-welding@googlegroups.com>
Reply-To: materials-welding@googlegroups.com
Subject: [MW:12354] SMAW ELECTRODE FOR P91 MATERIAL

Dear Group Members,

I am having 3 approved WPSs  for P91 material.These 3 WPS are using 3 different electrodes.

1)9018-B9   -Iron powder & Low hydrogen potassium coated
2)9016-B9   -Low hydrogen potassium flux coated
3)9015-B9   - Low hydrogen sodium flux coated

My doubts are

1)How we can justify which electrode is better for my use?
2)Any where in code it mentioned the suitable flux coating for electrode?


Regards

Jose Sebastian
+919687660525

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