welding two members together cjp without backing or backgoug

Date 12-27-2013 19:42

Dave,

WELCOME TO THE AWS WELDING FORUM!!

Let's see if I have this straight: your two members are a beam and a plate. You are welding the plate to the web of the beam (a doubler plate). It goes across the width of the web and stops short at the edge of the k (radius in the transition from the flange to the web). So, you are going to weld around it's perimeter and along the edges parallel to the flange you would fill up the gap until flush with the top of the plate.

If I have followed your description properly, then yes, that is a natural J bevel groove joint (not a flare groove) and would be a CJP weld when completed. It will also need continuous VT and followed up by UT when visually approved. BTW, if both sides had the curve it would be a U groove joint. Yes, you would consider the web to be the backing. Thus, it is not a CJP without backing but is a CJP with backing. No need to backgouge.

Hope I answered your question.

Have a Great Day, Brent

By SCOTTN

Date 12-27-2013 20:29

It does sound like you have a web doubler application. I was wondering if your application falls under the AISC Seismic Provisions. The k area (as explained by Brent) of rotary straightened wide flange sections may have reduced notch toughness, and there were preliminary recommendations from an AISC publication in 1997 that discouraged the placement of welds in the k area because of post weld cracking that occurred on past projects. When welds are to be placed in the k area, inspection of these areas should be performed to verify that cracking has not occurred. For doubler plates, where welding in the k area is performed, MT in the k area should be performed on the side of the member web opposite the weld location, and at the end of the weld. If both sides of the member web receive doubler plates in the k area, MT of the member web should be performed after welding of one side, prior to welding of the opposite side. Cracking in the k area is known to occur in a delayed manner, typically within 24 to 48 hrs. after welding. The cracks generally, but not always, penetrate the thickness of the base metal. The Specification requires only visual inspection of the k area after welding is performed in the k area, without a designated delay period. For the Seismic Force Resisting System, those provisions require additional MT to be performed no sooner than 48 hours after completion of these welds.

By jwright650 (*****)

Date 12-27-2013 20:35

Scott brings up a good point to check on.

By Blaster (***)

Date 12-27-2013 22:49

Depending on the plate thickness and radius and process, that could be a pretty tough weld since the welder wouldn't be able to get close to the optimum electrode angle. Needless to say the application of sound metal could be made a lot easier by applying a bevel to the edges of the plate.

I'd run some tests.

By welderbrent (*****)

Date 12-28-2013 00:40

I understand what you are saying Blaster but over the years I have welded lots of these and in the past several years as a CWI I have witnessed and inspected many more. Both wire feed and SMAW have been used, though mostly FCAW-G. No problems.

As John pointed out, Scott brought up a point I omitted about the MT of the k area. When welding doubler plates one has little choice but to weld in the k. Now, it is also important to understand the k. You have k, a small section through the radius itself. k-area, the area of the web that extends 1- 1/2" beyond the k. The k-area is the area of the most concern, and only in seismic applications under certain stresses calculated by the engineer.

So, it is important to note that for the most part this weld of the doubler plate will mostly involve the k in the radius portion and not the k-area.

But, with it's location right on the edge of the k-area and involving the k there is much concern and care is to be taken.

Have a Great Day, Brent

By jwright650 (*****)

Date 12-28-2013 11:24

>Without the bevel, it is almost impossible to get fusion in the corner of the plate

Depends....on how wide the flange is, how thick the web double plate is, and how close to the "k" the plate is detailed/sized to fit. Column web doublers is where you really have to monitor the fit-up and see how well the welder has access to the bottom of the joint(root) because column shapes/sections usually have wider flanges.

By welderbrent (*****)

Date 12-28-2013 13:41

I agree with John. And very few of the ones I have seen have had a bevel. And they have had little problems according to the UT.

The main contractor that I have inspected them on uses 3/32 FCAW-G with some pretty high volts and amps. It still takes a good welder to get the root in with proper fusion. But there are few repairs.

Have a Great Day, Brent

By SCOTTN

Date 12-30-2013 12:31

Here's an attachment from the AISC Seismic Spec. with three web doubler plate options:

Attachment: WebDoubler.docx (77k)

By welderbrent (*****)

Date 12-30-2013 13:28

I would make one other observation here, when adding only one doubler plate it is important to reinforce the flanges on that side so as not to distort the beam and cause it to be out of tolerance, even spread the flanges slightly then leave them braced until cool. It is amazing how far the weld at the edge of the web will pull things out of square. (Not that beams are perfectly square in the first place)

Great add Scott. I have never seen the third option before.

Have a Great Day, Brent

By SCOTTN

Date 01-02-2014 16:48

Also, in case some of you aren’t familiar with it, a “Clean Columns” programming tool is available for free downloading on the AISC site. It can be used to calculate the lightest column section that would be needed to eliminate stiffeners and web doubler plates. Once the joint forces are known, the tool will size the lightest column that can be used in the unreinforced condition. Substituting to a heavier column would obviously cost more for material, but the savings from eliminating stiffeners (continuity plates) and web doubler plates, i.e., eliminating the materials needed to make and prep them, the labor needed to fit them, weld them, and then inspect the welds, in some cases, would more than offset the additional cost of using a heavier column section. This tool would be especially beneficial for use with columns supporting several floors and having moments at each floor. If anyone considers using this tool, contact the EOR to see if he/she would be open to the concept. This should be done prior to submitting a bid, or no later than prior to the preparation of the advanced bill of material. Either way, submitting an RFI to the EOR could result in substantial savings to the fabricator. I haven't experienced being asked to cut our price based on approval of this change, but it's still a possibility.

http://www.steeltools.org/resources/viewdocument/?DocumentKey=543ffd70-d582-4f90-b24b-d0e2cf629f50