Ceramic Backing Strips

Date 01-22-2015 20:01 Edited 01-22-2015 20:07

Hello goldybowen21, to answer one of your questions: yes, I have used them and they are great, a little pricey, but wonderful for backing open root welds. They are also available with various reliefs cast into their contacting surfaces to provide for shaping the through penetration of the root weld.

As to the second: There are instances where back grinding/back gouging is required, having a simple way to remove this backing speeds up the ability to access the backside of the weld to complete the additional preparation and welding. Ceramic backing is generally removed very readily with a tack hammer/needle scaler, and then wire brushing, either by hand or powered.

A disadvantage however, is the ability to set-up the welded joint to position it for welding. If the parts are solely welded together in a single joint you will have to position/clamp/ or otherwise orient the parts to hold them until you have at least the first connecting root pass in place. Others will likely have additional information but I believe that you can get the idea. Best regards, Allan

P.S. I have included a "little" sketch, sorry. In this example you might possibly use metal backing to make the full pen. welds or you might be directed to use the ceramic backing if it was determined that the backings would need to be removed for some reason.

Attachment: Beamcopewithaccessholes.bmp (50k)

By welderbrent (*****)

Date 01-22-2015 20:55

I have both used them personally and witnessed many welds done while doing inspection with ceramic backing.

A couple of points to consider:
1) If the joint calls for backing to be left in place, then your procedure must be qualified per Clause 4. Only steel backing is pre-qualified for left in place backing.
2) If you can remove and backweld then ceramic can be used as Allan described as to preparation for backwelding. There is a Technical Inquiry to back that up.
3) They can be a challenge for some applications as you may need something else to support one member while using the adhesive strip to hold the ceramic in place and getting your root pass, or more, run. You don't have that problem with steel.
4) The key part of your question is in the phrase "the best type of backing available,". That is wide open to interpretation of opinion, application, and operator preconceived ideas let alone skills.

I would highly recommend them when at all practical.

He Is In Control, Have a Great Day, Brent

By SCOTTN

Date 01-22-2015 21:25

A lot of sales literature claims that the weld quality will be such that backgouging and back welding will not be necessary. My experience with ceramic backing is that this is not always the case. As Brent said, the use of ceramic backing is not prequalified. Furthermore, you’ll need to use the proper shape and size of ceramic backing in order to obtain the type of results you want, and it must be properly placed on the joint. Fit-up conditions are critical for the use of ceramic backing. You’ll find in many cases that even with the ceramic backing, variations in such fit-up characteristics as root opening, root face, misalignment, etc., result in an unacceptable weld condition that may require backgouging and back welding. Ceramic backing may also be difficult to use for some joint configurations, resulting in backgouging and back welding as well. Another consideration is that ceramic backing is porous, and is therefore subject to picking up moisture. If your application is sensitive to hydrogen, you'll want to treat the ceramic backing much like the other weld consumables with regard to atmospheric exposure limits. Though not as sensitive as SMAW electrodes, for instance, you don't want to leave them lying around and exposed to rain, dirt, etc., and they should be placed on the joint immediately prior to welding.

By welderbrent (*****)

Date 01-22-2015 21:47

Ultimately it comes down to operator skills and experience. Those who know how to deposit weld over non-steel backing such as copper, ceramic, aluminum, etc will deposit good weld while using ceramic. Those who don't, won't.

All consumables have unique handling and storage requirements. Variations in application and conditions such as root opening, bevel angle, backing fitup, electrode in use, etc will also bring about unique requirements.

So, when you say 'best' it just all depends upon what all the applicable conditions are. And, the you need to ask, for what purpose and end result am I considering using ceramic?

He Is In Control, Have a Great Day, Brent

By TimGary (****)

Date 01-22-2015 21:43

It's great beacuse it works well and comes in many different configurations to fit different joints, and can also come attached to heavy duty aluminum tape so that it sticks where you want it to stay.

But, it's an expensive single use consumable.
And
When the tape fails so that parts of the backing falls away, it creates a large amount of re-work.

Tim

By Tyrone

Date 01-23-2015 11:35

Compared to fiberglass rope that we use to use for backing, it's a dream.
Tyrone

By SCOTTN

Date 01-23-2015 14:56

It's so much better than the copper flat bar (2" x 3/8) backing that we used to use in the late 70's.

By aevald

Date 01-23-2015 15:25

I'll second that Scott. Best regards, Allan

By aevald

Date 01-23-2015 15:24

Ouch Tyrone, fiberglass rope? I guess I have indeed been spoiled, never had that experience. I did however use plenty of brass/copper backing and then ground/air arced the backside and cleaned everything up in order to finish the weld properly. Best regards, Allan

By Dualie

Date 01-25-2015 22:55

I must be old school in that i prefer the copper or graphite backers to the ceramic

By Tyrone

Date 01-26-2015 11:53

Hi Allan,
The tape is still available from a few different manufacturers.

http://weldbacking.com/fibre_glass_weld_backing_tapes.html

One good thing about is was that you could bend it to shape it to irregular joints.

Tyrone

By aevald

Date 01-26-2015 15:14

Hello Tyrone, looks as if they have a pretty wide selection of products to cover a lot of different scenarios. Thanks for including that link. Best regards, Allan

By ssbn727 (*****)

Date 02-04-2015 04:12

Is this what you're writing of?

http://weldingdesign.com/site-files/weldingdesign.com/files/uploads/2014/10/HTF_TechPaper1.pdf

Respectfully,
Henry

By Blaster (***)

Date 01-26-2015 14:37

I use to use it for structural connections... beam flanges primarily. Ceramic tiles work awesome as long as the fit up allows its use. I don't think it is too feasible to plan on only using ceramic unless there is tight control over fit up. It works best when the welder has an option to use it or steel as the specific conditions warrant. Steel is much easier to use when the surfaces have a fair bit of misalignment, when two different thicknesses are being joined as a butt joint, when the root opening is very wide, or any time the root will require more than one bead (since the adhesive is burned up after one pass).

By ssbn727 (*****)

Date 01-26-2015 22:30

@ EB we used ceramic backing strips when the hull sections were to be welded together in order to assemble the entire vessel resulting in a watertight vessel to launched into a wet dock...
In fact all of the submarines we built @ EB during my time over there were welded together with the use of ceramic backing strips which were basically ceramic tile with a slight groove on each of the tiles and glued to a type of aluminum tape if I remember correctly... Each hull joint was approximately 125.6 feet in length and a total of over 1500 ft. of hull joints to be completed prior to launching of each Trident Ohio class boat... That's a lot of ceramic backing tape even just for the hull joints! We used the backing tape in some of the tanks inside each of those boats also... When they were completed, the length of backing tape was around 1/4 of a mile or so...

EB had a welding school located @ the South Yard of the Shipyard and all of the welders would qualify over there for multiple processes as well as specialized welding techniques also and welding the root joints with ceramic backing tape was one of the many EB/USN welding quals that anyone who was to weld on the submarine n a joint that used ceramic backing tape had to be qualified or they weren't allowed to weld anywhere that had ceramic backing tape... The amount of training time allotted was one week and if if didn't pass, you would end up welding decking or some other lousy job assignment but, you were allowed to re-qualify after 6 months and if you brown-nosed your foreman enough. :eek:

Yup! Welding on ceramic backing wasn't hard to learn but, if you had no experience with it you would be surely disappointed with your first results no matter how good of a "golden arm" you thought you were back then... I wonder if they still use the tape? Probably in certain circumstances because they no longer use it for the Hull joints from what was described to me by one of my "compadres" that still works there and is now a big shot Ship Superintendent these days... There's no longer the need to use ceramic backing tape for the hull section joints since they no longer oxy-fuel cut and then grind the bevels for the hull joints ever since they started to machine the joints to a custom configuration as each section was being built from raw materials, and each half of each joint would be protected in case of damage from transport starting @ the Quonset Point yard in Rhode Island to EB in Rotten Groton, Connecticut.

Respectfully,
Henry

By Tyrone

Date 01-27-2015 11:38

Hi Henry,
Was the tape used to bridge the root gaps due to the oxy-fuel cuts and grinding, or because they were full pen. joints using backing?

I suspect the full pen. joints were designed out, therefore the tape is no longer required.

Tyrone

By ssbn727 (*****)

Date 01-28-2015 02:03

Both.

By TimGary (****)

Date 01-27-2015 13:45

A while back, I was involved with creating a procedure using ceramic tape while making full pen welds on carbon steel pressure vessels.
The ceramic was 1" square x 3/8" thick ceramic blocks with a 3/8" wide concave groove in the middle, 1/16" deep.
The ceramic blocks were aligned on 3" wide heavy aluminum tape.
The goal was to SAW head and shell butt welds from the outside and eliminate back gouging on the inside, which is no fun while inside a vessel.
The joint was a single vee on 1/2" thick steel with a 1/8" land and 3/32"" root opening.
Welding was done in a single pass.

The test welds worked great, the root was nicely shaped with no defects. Eureka! no more back gouging!

We proceeded to weld 3 vessels. Something caused the tape to come partially unstuck in several areas along the joints, while welding.
The operator was foolish and just kept going without resolving the issue. Not sure why.

The weld roots were good where the tape stayed adhered, but grossly defective from excess root reinforcement and LOF where the tape came loose.
Backgouging defects and repairs with FCAW ensued, with horrible results. It took 3 - 4 rounds of repairs and RT to clean out all of the slag inclusions before it was done.
Afterward, Management killed the use of ceramic tape.
All because of incompetent Operators and possible deliberate sabotage.

Every other time I've used ceramic tape and taken stepd to ensure good adhesion, it worked fine.

Tim

By 46.00

Date 01-27-2015 15:53

I too, have had good results using ceramic backing tiles, although I would agree that wear operator apathy is present, the results can be very time consuming to correct. One way of preventing problems with the tiles coming adrift or not fitting tightly is to use a series of strong backs and small wedges on the reverse side. Takes a bit more time but the results are worth it. It also stops any problems with the wire pushing the tile away from the plate.

By Lawrence (*****)

Date 05-12-2016 14:09 Edited 05-12-2016 14:12

Hi and Welcome to the Forum Martin,

No

AWS D1.1 2015
3.13.2.1 Prequalified CJP groove welds detailed without
steel backing or spacers may use backing other than steel
as listed in 5.9.3 when the following conditions are met:
(1) The backing is removed after welding, and,
(2) The back side of the weld is backgouged to sound
metal and back welded.
Welding procedures for joints welded with backing other
than steel in which the weld is to be left in the as-welded
condition without backgouging and welding from the
other side are not prequalified.

The only way you can use other procedures are if you back-gouge to sound metal all CJP grooves.

By martinadams Date 05-12-2016 14:42

Excellent thanks for response

By welderbrent (*****)

Date 05-12-2016 17:43

Oh come on guys. Read the fine print. Notice what it says about being left after welding.

The answer is YES IF you are going to remove the ceramic backing and clean and backweld.

There is not enough information to make a dogmatic NO statement.

I also back this up normally with a quote from a technical inquiry which asks this question and was a definite 'yes it can be used' unless it is going to be left in place after welding from the first side. THEN it needs its' own PQR and subsequent WPS.

Brent

By Lawrence (*****)

Date 05-12-2016 22:42

What are you even responding to?

By welderbrent (*****)

Date 05-13-2016 01:40

That's why people need to start their own threads with a new question.

But, it all has to do with ceramic backing though I was responding to martinadams.

You most definitely can use ceramic backing without getting a PQR on it. As long as you totally remove it after welding from the first side, clean it up by whatever means, and weld the second side. There is a technical inquiry addressing this issue. And I will go get it in a moment and put it on here.

Only steel backing is pre-approved for left in place backing. To leave 'other than steel' backing in place one must get a PQR.

Brent

By welderbrent (*****)

Date 05-13-2016 01:45

Subject: Other than Steel Backing and Prequalified Joints
Code Edition: D1.1:2008
Code Provision: Subclauses 2.17 and 5.10
AWS Log: D1.1-08-I02
Inquiry: Can the use of backing “other than” steel be considered prequalified where back-gouging and
welding is performed on the second side?
Response: Yes, provided all conditions for a prequalified weld are met. Backing other than steel
is not a prequalified substitute where steel backing is required.

By welderbrent (*****)

Date 05-13-2016 01:50

And BTW Lawrence,

I believe the code quote you provided and your own statement at the end also state thus. I was not responding to you, but, to the OP. It appears to me that you and I agree though I am curious about why you state "NO". With the information provided by the OP I would state YES though with reservations until more information is available.

Brent

By ssbn727 (*****)

Date 05-13-2016 13:36

Umm, I believe there is a bit of a difference in the interpretation of post answers from both Lawrence and Brent.... Because if you look at both responses and compare what is written between the two within different parts of each answer... You will notice this:

Yes, provided all conditions for a prequalified weld are met. Backing other than steel
is not a prequalified substitute where steel backing is required....

That is the reply from Brent... Now will look at Lawrence's post where the exception to the rule is noted plain as the day...

AWS D1.1 2015, 3.13.2.1 Prequalified CJP groove welds detailed without steel backing or spacers may use backing other than steel as listed in 5.9.3 when the following conditions are met:

(1) The backing is removed after welding, and,

(2) The back side of the weld is backgouged to sound metal and back welded.

Welding procedures for joints welded with backing other than steel in which the weld is to be left in the as-welded
condition without backgouging and welding from the other side are not prequalified.

what I take from both answers is both yes & no are noted with respect to what is allowable depending that ALL conditions are met producing what can be called an exception to not being allowed... So you're both right! I completely understand why your initial response was no Lawrence...It was a no because the original qualification was produced according to section 4...Therefore the substitution and use of ceramic backing without documentation noted in the original WPS/PQR is not allowed and yet, can be easily addressed via qualification... Bottom line is it all depends on the details... Time to go see one of my many doctors who are keeping me living with good quality of life so far even though some might beg to differ, but hey
as long as I'm grateful it will be good... Gotta go!

Respectfully,
Henry

By Dreizehn (*)

Date 05-13-2016 20:19

Is it considered open root since ceramic is not fusible(fuseable?)?

By jwright650 (*****)

Date 05-13-2016 21:25

Dreizehn,
No it is not an open root, ceramic is still a backing....

Guys,
D1.1:2015 has clarified what I had been discussing/disagreeing with a few other local CWIs for years now. Ceramic backing can be used in a pre-qualified joint as long as the ceramic backing is removed, the second side is back gouged to sound material and re-welded.

By martinadams Date 05-16-2016 11:13

Hi Gents
The answer I received relating to ceramic backing is informative enough for me to make a clear decision. Thanks

Another question , let me try and phrase it as best as I can to prevent any mis-interpretation.

Code : AWS D1.1

I have a WPQR that is qualified using the GMAW process, when I referenced the WPS I noted that it references FCAW. I rejected it ???

Question 1 : I rejected it based on process being an essential variable , if they want to qualify to GMAW - it should have been indicated this on the WPS
Question 2 : Couldn't they simply have included both processes (e.g. GTAW and FCAW) in their WPS - similar to ASME 1X (e.g. GTAW/SMAW)

Can