wps tubular T-Y-K connects

Date 05-05-2008 02:29

Can you use a TC-U4a, back the tube a quarter inch off the plate, with a 1" thick solid backer plate halfway in the tube? I'd think that would get you into prequalified

By 803056

Date 05-05-2008 04:34

You would have to qualify the procedure by welding a sample and subjecting it to the tests required by Section 4.

The solution offered by Duke seems to be a good alternative or prefit backing bars to the tube. Select the appropriate thickness and heat them so you can bend them to fit the tube. Meeting the requirements of a prequalified joint makes life so much easier.

Don't forget, once you qualify the procedure, should you elect to follow that slippery path, you also have to qualify the welders. Not an easy task.

Best regards - Al

By strat

Date 05-05-2008 10:17

Thanks,
We do prefit backing bars as you guys stated. I was reading through section 4 and that kinda caught my eye and I was wondering if you did all of the processes in 4.12.4.1 that you could write a qualified wps.I wasnt sure if there were any kind of tension test to go with it.

Thanks
strat

By hogan

Date 05-05-2008 17:17

would a tube to plate be considered a t-y-k ?

By 803056

Date 05-06-2008 03:18

I don't believe it would be. The T,K, and Y are for tube to tube connections.

However, if the fabricator decides to qualify the procedure, the test regiment required is listed in the appropriate tables of Section 4.

Best regards - Al

By strat

Date 05-06-2008 11:06

ok now im confused,4.12.4 t,y,or k connections without backing welded from one side. 4.12.4.1 wps without prequalified status
(1) Qualification in conformance with figure 4.27 for pipes with outside diameters greater than or equal to 4"
or Figure 4.27 AND Figure 4.29 for box tubes ect...

is that stating that if you choose to go that route (which I dont think I would wont to tackle) that to comply you wuold have to do both figures 4.27 and 4.29 for box tubes

By hogan

Date 05-06-2008 16:35

strat, i believe that you will need to qualify your procedure due to welding from one side without backing. This however is not in the category of a t-y-k connection. The t-y-k requirements only apply to tube to tube connections.

By kipman

Date 05-07-2008 05:07

Gentlemen,
You are confused. TYK requirements are not applicable only to "tube to tube connections". Check out the definition in D1.1 Annex K for "tubular connection". It states "a connection in the portion of a structure that contains two or more intersecting members, at least one of which is a tubular member". Therefore a T, Y, or K connection joining a tubular member to a flat plate is also a tubular connection, and the relevant TYK rules are applicable.

This makes sense if you think about it. Take a simple Y connection between a tubular member and flat plate at a brace intersection angle of 45 degrees - you still have varying groove angles as you go around the circumference of the joint. As a matter of fact, this is in some respects more difficult to weld as you do not have the benefit of the extra shoulder space provided by the curvature of the chord member in a tubular-to-tubular connection.

If you look closely at the prequalified TYK requirements, you will find that the prequalified TYK joint details can only be applied to the simplest TYK joints and as you approach a brace intersection angle of 60 degrees or less it is almost a guarantee that you will find yourself outside of the prequalified joint ranges (because the groove angle in the joint heel will be less than 30 degrees).

Hope this helps,
Mankenberg

By Richard Cook (**)

Date 12-31-2008 18:06

Kipman

I know this is months down the road from this entry but it is as close to the debate I'm into now. I hope you get alerted.

2.21 in D1.1 states "Memebers in tubular STRUCTURES shall be Identified as shown in Figure 2.14." In this figure it clearly shows that a T, Y, K connection is between intersecting members of HSS shapes, these are types of "tubular connections" that require specific considerations. With your theory all connections would be a T, Y, or K which in my opinion is ncorrect. You may have "tubular connections" that include "T-joints" that are not "T connections for tubular structures", such as a baseplate on tube steel or a tube member welded to the top of a wide flange.

To further understand the requirements, AISC helps to clarify the conditions. In "HSS Welding Requirements in AWS D1.1" (section 8 page 24) you find these statements, "apply to welded HSS to HSS connections" and "while Part D deals primarily with HSS-to-HSS connections,"
Look into these.

You rely solely on a definition (tubular connection) to establish your theory, but find the definition for T, Y, or K connection and rethink your opinion. Also the whole concern in the industry is dealing with the "welding with out backing" issue in this type of connection. You cannot get adequate backing in place due the geometry of the connection. We need not "read" to much into the requirements, keep it simple.

Please consider these references and responed, this has been an ongoing question through out our industry. I have seen it go both ways, and those with the "authority" usually win out even if they may be wrong.

By hogan

Date 12-31-2008 18:19

Also in annex k tubular connection is defined but tubular t-k-y connection is not defined

By GRoberts (***)

Date 05-06-2008 17:21

The joing is either Tubular or non-tubular. If it is tubular, you could use TYK configurations. If it is non-tubular, you could use the pre-qualified skewed T joint details in figure 3.11- for non tubular. Is the joint tubular?- It probably depends on how the designer calculated the stresses.