My mistake, I was thinking of the basic 7018 eletrodes. The 6010 electrodes are kept in their package until being used for the root pass. Sorry for the mix-up. JZ
--- On Tue, 9/29/09, Shashank Vagal <nach_sam@yahoo.com> wrote:
From: Shashank Vagal <nach_sam@yahoo.com>
Subject: [MW:3368] Re: R: 3361] Re: Heat Input
To: materials-welding@googlegroups.com
Received: Tuesday, September 29, 2009, 5:19 AM
Hi,
Something is wrong here. Cellulosic electrodes are not to be subjected to any temp > 5o deg C or they will deteriorate as far as the bonding cellulose is concerned. They are never baked for this reason. Am I right or wrong?
Shashank Vagal
--- On Tue, 29/9/09, Jeremy Zibin <jzibin@yahoo.com> wrote:
From: Jeremy Zibin <jzibin@yahoo.com>
Subject: [MW:3364] Re: R: 3361] Re: Heat Input
To: materials-welding@googlegroups.com
Date: Tuesday, 29 September, 2009, 2:12 PM
| Francesco, I agree that the cellulosic electrode is problematic for low temp. applications, especially for danger of H2 cracking. There is usually tight quality control on the electrodes and they are always in rod ovens prior to use. Also, the root pass is limited in thickness, 5 or 6mm if I remember properly on the WPS, applied with a small diameter electrode. The second pass (7018) or hot pass is applied immediately after the root pass and it blends in with the root pass and thus creates a mixture of 6010 & 7018 in the root (i.e. the root is not totally 6010 in mech. properties). I'm just adding to the discussion what I've observed in the oil & gas industry in Canada. The welding with 6010 & 7018 for LTCS is quite common and it is approved from very large clients at multi-billion dollar sites that have been in operation for 20 years or more, so I would think these people know their welding, especially in the cold temperatures of Northern Canada where it is not uncommon to see -50 or -60C during the Winter. Of course a GTAW root would be of higher quality and shouldn't have any issues with low impact resistance but this process is impractical/uneconomical for production welding on construction sites where manual welders are welding hundreds or thousands of pressure piping joints everyday. Not to mention, you would have trouble finding enough welders that could TIG roots on these large construction sites in the oilsands. Regards, JZ
--- On Tue, 9/29/09, Cotzia Francesco <Francesco.Cotzia@saipem.eni.it> wrote:
From: Cotzia Francesco <Francesco.Cotzia@saipem.eni.it>
Subject: [MW:3363] R: 3361] Re: Heat Input
To: materials-welding@googlegroups.com
Received: Tuesday, September 29, 2009, 1:13 AM
The use of cellulosic electrode for low temperature carbon steel is not quite appropriate. Sometimes and especially nowadays there some product classified as E6010 that can bear CVN at -46°C. I don't know the diameter of root pass electrode, the WT you have used for PQR nipple, but I think that the weld metal deposited by cellulosic electrode is not more than 2mm. When you are extracting the CVN specimens, you will never test them the root pass. Then you are not sure that the E6010 will resist at -46°C. This risk will be increased if you are using high heat input. If you are using this type electrode, you are increasing the risk to have hydrogen cracks especially in the root. I would suggest to use GTAW or low hydrogen electrode (E7016-1) for the root pass. Regards F
Da: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] Per conto di Jeremy Zibin
Inviato: martedì 29 settembre 2009 9.56
A: materials-welding@googlegroups.com
Oggetto: [MW:3361] Re: Heat Input
We've used qualified welding procedure specifications for LTCS that specifiy a root layer of 6010 (but only 1 root layer and no hot-pass) and then fill and cap layers with 7018. This welding was performed on pressure piping under B31.3 for use in Northern Canada (min. design temp. of -46C). The WPS was qualified, stamped by professional welding engineers and approved by the client.
It is my understanding that the root lay is limited in thickness on the WPS and therefore the total thickness and properties of the full weld are majority 7018, which is approved for LTCS. The heat input is limited to a max. on the WPS so that the welded joint should have the adequate impact properties at low temperatures. This will be proven during qualification but remember not to limit yourself on heat input on the WPS, use a typical heat input for your welding process and material thickness to pass the qualification.
--- On Mon, 9/28/09, Muhammed Ibrahim <ibratech@gmail.com> wrote:
From: Muhammed Ibrahim <ibratech@gmail.com>
Subject: [MW:3358] Re: Heat Input
To: materials-welding@googlegroups.com
Received: Monday, September 28, 2009, 11:16 PM
E6010 will support up to -29 degree celcius only and used in pipe line root application. But if the PQR passes the impact you can use it with batch restriction. E 7018-1 is acceptable up to -46 degree but selection E 6010 is not suitable for LTCS ! As per which clause it is selected for LTCS ?
Regards
Date: Tue, 29 Sep 2009 09:49:23 +0530
From: nach_sam@yahoo.com
Subject: [MW:3354] Re: Heat Input
To: materials-welding@googlegroups.com | Adi, Heat input is a guideline for subsequent welding. The yardstick is the average value as obtained from your PQR. Your production welding should not exceed PQR HI values. By the way, is 6010, 7018-1 Ok for LTCS? What is the working temp?
From: Adi <adinraos@gmail.com>
Subject: [MW:3352] Heat Input
To: "Materials & Welding" <materials-welding@googlegroups.com>
Date: Tuesday, 29 September, 2009, 9:35 AM
I have done the PQR for LTCS by using 6010 & 7018-1 as per ASME SEC IX
some time i got 5KJ heat in put
What is the limitation for heat input and where it is mention?
Adi
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