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Up Topic Welding Industry / General Welding Discussion / ceramic backing
- - By prowelder (*) Date 05-30-2007 14:22
Ive been looking into using this material for full pen welds. can anyone tell me if I have to change my welding procedures for using this even though it is easily removed and is not consumable?
Parent - - By Joseph P. Kane (****) Date 05-30-2007 16:25
In my opinion you will have to requalify under most codes.  Plus - It doesn't always work as easily as advertised.  Root bead condition is different than what you get with just open root of metal or even copper backing.  I never had any consistent luck with root pases when using it with Aluminum.
Parent - - By jon20013 (*****) Date 05-30-2007 16:42
I cannot speak for AWS codes but you would not need to requalify procedures for ASME Codes.  On the other hand, we have found the use of ceramic backing (with FCAW process) to be excellent for full penetration welds on carbon steel materials.
Parent - - By prowelder (*) Date 05-31-2007 10:54
Thank you for your input but imm still confused.
Parent - By jon20013 (*****) Date 05-31-2007 12:54
I guess I don't understand your confusion?  You wrote "Ive been looking into using this material for full pen welds. can anyone tell me if I have to change my welding procedures for using this even though it is easily removed and is not consumable?"

Joe Kane, who is a renowned expert in structural applications made an excellent response, mine was somewhat contrary to his but based on my experience.  You didn't tell us what code applies to you so it's difficult to provide a specific response however if you are governed by ASME IX rules you do NOT have to requalify your procedure.
Parent - - By waynekoe (**) Date 05-31-2007 15:11
If this involves D1.1, then yes, you do have to submit a WPS stating the use of a ceramic backing, or, what ever non consumable backing your going to be using, as well as  conditioning of the root weld and back weld instructions. It's still a prequalified procedure and doesn't effect your welders certification coverage for the joint. It just needs to reflect the change in the way the weld is going to be constructed. Keep in mind, that if the instructions in the weld symbol tail just list "CJP", you can use which ever backing type best fits your needs. But, if the engineer has detailed metal backing, you need to communicate with him or her, first.
Parent - - By Joseph P. Kane (****) Date 05-31-2007 20:46
I disagree with you, where you say ceramic backing is "Prequalified" (Under D 1.1). The Paragraphs under 5.2.2 specify that the backing shall be steel.  There are no prequalified joint details using open roots in Figure 3.3 and 3.4.  Figures 3.5 through 3.9 show open root on tubulars and do not show backing other than steel.  To be "prequalified", one must comply with the prequalified joint details in Section 3.
Parent - By hogan (****) Date 05-31-2007 22:10
i read this to say that if you use steel for backing, that it shall conform to listed requirements. i do not see where it states that backing shall be steel (D1.1-06). this is also under the heading of base metal. looking at 5.10 it lists ceramic as backing that may be used. preventing melt through seems to be the only requirement. am i missing something ?
Parent - - By QCCWI (***) Date 05-31-2007 22:15
Ceramic backing is "Prequalified" per AWS D1.1 2006.  Read Section 5.10.

If you are going to backgouge to sound metal before welding the second side, ceramic backing is considered "Prequalified". If you do not backgouge, it is considered a partial joint penetration weld. If you do not plan on addressing the second side then steel backing is the only backing "Prequalified" by D1.1.
Parent - - By CWI555 (*****) Date 06-01-2007 02:15
06 edition: There are several listings for what to do with, how to do it, etc for steel backing.
2.17 Prohibited Joints and Welds
states that welds made from one side with or without backing, other than steel without having been qualified in accordance with section 4 are prohibited.

5.10 simply states that ceramic can be used.

I don't see anywhere where ceramic is prequalified, and based on the statements in 2.17 I think it's the intent to qualify rather than be considered pre qualified.

my two cents worth,
Gerald
Parent - - By Joseph P. Kane (****) Date 06-01-2007 14:06
waynekoe

I disagree your contention that the welders are still qualified.  If they had qualified on an open root test, perhaps they can be considered prequalified.  Table 4.12, Essential Variable (6)  says;  The omission of backing (if used in trhe WPQR test)   However, ceramic backing is not steel backing, and steel backing is an essential variable for prequalification.  Therefore, the omission of steel backing by substituting ceramic backing would make it an open root joint.   Thus, if the welders qualified with the typical steel backed joint found in Figure 4.21, 4.22, and 4.23, they would not be qualified.  If they qualified using figure 4.24, 4.25, 4.27, 4.28, or 4.29,  It would still be a stretch for me, but in that case the welder might be considered qualified.

Gerald

In addition to the paragraphs you quoted here, paragraph 3.1, third sentence, it says that in order to be prequalified, the WPS must comply with Section 3.
Parent - By makeithot (***) Date 06-16-2007 16:52
Joseph, I have often wonderd about qaualifing on an open root and not being qualified on a backing strip ceramic or other wise haveing not studied D1.1 extensively canot comment on it's content. But with W47 which is the CWB code on structural steel one has to qaulify in both. I have never been given a striaght answer as to why this is the case,as I would off thought that if a person can pass a open root he should surely be able to pass a backing strip weld ceramic or other wise. I do relise ofcourse that each one presents it's own set of problems. I would have to agree that it would be a stretch for one to be preqaulified for both. Other wise I have used ceramic backing alot and the results have always been good and the nice thing is the backing is easily removedand when speed of the process is an issue it is the only way. My 2 bits.
Parent - - By waynekoe (**) Date 05-31-2007 22:59
The details in figures 3.4 say nothing about backing type, and 5.2 only states "when steel is used". Fig. 3.3 is for partial pens, no backing required.
Parent - - By kipman (***) Date 06-01-2007 14:24
Gentlemen,
If you have access to "The Official Book of D1.1 Interpretations", check out the interpretation given for AWS Log #D1-259.  The official interpretation reads, "Yes.  Ceramic backing is not prequalified under this Code.  A change from steel backing to ceramic backing will require a new WPS to be qualified in accordance with Section 4 of the Code."
Hope this helps,
Mankenberg
Parent - - By waynekoe (**) Date 06-01-2007 14:49
I stand corrected. In reading the commntary for 5.10, it does exclude all other types of backing from prequalification. Thank you for your input and knowledge.
Parent - - By jwright650 (*****) Date 06-01-2007 14:59
Wayne,
This paragraph is speaking of welds welded from "one side only" must be welded with steel backing(except for tubular). I don't read this as saying that you can't remain prequalified if you use ceramic or other nonfusible backing, as long as you address the second side of the joint.
Parent - - By waynekoe (**) Date 06-01-2007 15:54
Well, now I'm really confused! I don't think that I can handle this much strain on a Friday morning. So, I'm going over to the wall outlet, stick my tonge in the slot and gather my wits. Hold on just a minute!...................................................Ahhhhhhhhhhhh, That's better. So, what I'm seeing here is that unless AWS starts including the book of interpretations along with their freakin code book-----wait a minute--back to the wall.........................
Parent - - By ross (***) Date 06-01-2007 19:50
The interpretations are available online, free, here: http://www.aws.org/technical/interps/

Ross
AWS Marketing
Parent - By waynekoe (**) Date 06-01-2007 21:27
Con mucho gusto
Parent - By Joseph P. Kane (****) Date 06-01-2007 16:47
I agree that a joint that is to be back gouged could be backed with any non melting product and still be prequalified.  My previous  responses were based on the single welds from one side.
Parent - By jwright650 (*****) Date 06-01-2007 15:08
Paragraph 5.22.1 even lists the types of backing that can be used for fillet welds should the root be out of tolerance.
Parent - By js55 (*****) Date 06-01-2007 16:25
Kip,
That brings up an interesting question. Does anybody know why AWS abandoned Interpretations?
Parent - - By CHGuilford (****) Date 05-31-2007 16:35
And just in case you are asking if you physically need to do anything different to use ceramic backing - generally no.  The same basic parameters and technique should work OK, you just need to remember that ceramic will not conduct electricity so your arc has to stay on the base and/or weld metals.
Parent - - By Bob Garner (***) Date 05-31-2007 20:51
I've seen the ceramic backer bar that is tapered along one edge, that allows the root weld to be the reinforcing weld on the far side of the joint.  This way, you don't have to back-gouge and weld the reinforcing fillet.  This would seem to be different enough to require prequalification.  Has anyone used these tapered ceramic backers?

Bob Garner
Parent - - By ZCat (***) Date 05-31-2007 23:39
We used some in Alaska that had a little dip or indentation running down the center. If we were making a 90 degree beam butt we would tape the ceramic tilted so it would make a full pen on the back side.
Parent - By prowelder (*) Date 06-01-2007 11:23
These posts in regard to the ceramic backing have helped a great deal thank you very much for your comments .
Parent - - By cwi-cws (*) Date 06-15-2007 01:33
prowelder, d1.1 states that you only have to requalify with the omission of backing,table 4.5 #34 and table 4.12 (6) ,you should write a wps for the backing you will be using ,it will be a big help to your welders .we use ceramic,a109 rings and a36 ,ceramic works well when you have to remove backing and grind flush .you may have centerline cracks if your root pass is too concave ,or if the width to depth ratio is off.we use very little restaint whenever possible. hope this helps
Parent - By Bill M (***) Date 06-15-2007 13:07
js55 had a great question a few posts up-
 
Why did AWS abandon Interpretations?
Up Topic Welding Industry / General Welding Discussion / ceramic backing

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