Eng-Tips is the largest engineering community on the Internet

Intelligent Work Forums for Engineering Professionals

Register Log in
  • Congratulations waross on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Closure Plate for HSS Column, Seal Welded? Strength? 2

Status
Not open for further replies.
Rainbowtrout

Rainbowtrout

Structural
May 8, 2014
36
US
Hey all,

I am putting a closure plate at the top of a HSS column. I would like to make it water tight - thus seal welded. I am reading mixed opinions on seal weld strength here. The structure has roof deck and the closure plate need to be able to hold down the roof deck - the max un-factored load is approx. 2 k. Will a seal weld do? Here is how I have it right now. Should I specify the size of the seal weld? Really any size will do for this. What symbol should I use?

Also, I am curious - for a practical standpoint, how does the shop person get the closure plate inside the HSS column perfect and weld?

30blgfn.jpg
 
Replies continue below

Recommended for you

Sort by date Sort by votes
If noting can load it higher than that that, seal weld is a designation, but not a specification.

To illustrate, my welder walks back in at 11:45 and tells me he had "seal welded" the plate. Do I tell him to go add more metal, or do I tell him to go do the other column plate in the afternoon? How much weld is a "seal weld" ?
 
Upvote 0 Downvote
A "seal weld" is generally considered to be non-structural. If you want the weld to take load, then design a properly profiled weld. You might consider beveling the top of the HSS tube and placing the closure plate on top of that. You would then have a single bevel, complete or partial penetration structural weld around the entire perimeter of the plate and a flat surface upon which you could attach whatever you want for roof uplift.
 
Upvote 0 Downvote
From the sketch, it appears the HSS column might be an open section beam rather than a tube. Is this correct, or is the HSS column a tube? If the HSS column is a tube, and you want the 1/4" plate closure to be flush with the top edge of the column, then you'll need to inset the plate and use a bevel weld around the perimeter. The tricky part is making sure the bevels on the tube and plate edges will permit a satisfactory weld given the apparent difference in section thickness.
 
Upvote 0 Downvote
If possible, make it a cap plate, overlapping the column enough to provide your design fillet weld all around.

Michael.
"Science adjusts its views based on what's observed. Faith is the denial of observation so that belief can be preserved." ~ Tim Minchin
 
Upvote 0 Downvote
Most secure is to bevel the edge of the 1/4 inch flat plate at 45 with a 1/16 nominal flat left, then specify a fillet weld all around the top of the vertical tube steel.

If you do not a perfectly flat top, then do NOT require the top be ground flat. That will save a lot of time on each vertical tube steel joint.
 
Upvote 0 Downvote
The weld size for either a fillet weld or a partial joint penetration weld must meet the size limitation of AWS D1.1.D1.1M if the structure is in the US. The required weld size is the larger of that required to transmit the applied load or the minimum size required by the appropriate tables found in D1.1 or the AISC Steel Construction Manual.

Best regards - Al
 
Upvote 0 Downvote
Hey everyone! Thanks for the responses. They were very helpful. I think I will specify a closure plate the same size as the HSS's outer dimension - I will specify a bevel weld.

Question, will the bevel weld give a good seal? My primary concern is to avoid getting moisture in the column. Can I specify the bevel weld a seal weld?
 
Upvote 0 Downvote
If you bevel the plate, the normal default decision, you will have to shape it at the corners: better bevel the tube instead.

Michael.
"Science adjusts its views based on what's observed. Faith is the denial of observation so that belief can be preserved." ~ Tim Minchin
 
Upvote 0 Downvote
Nah. Beveling the simple plate - yes, at the corners too, is easy and cheap. It is simpler to bevel (run a grinder) around the outside of a flat plate than inside a tube steel rectangle.

Well, a weld will give a good seal. A bevel weld will give you an easier weld. Just to prevent water vapor entry a 1/8 or 3/16 or 1/4 weld is more than adequate.
 
Upvote 0 Downvote
The bevel would be on the outside of the tube unless you want to leave a welder inside.

Michael.
"Science adjusts its views based on what's observed. Faith is the denial of observation so that belief can be preserved." ~ Tim Minchin
 
Upvote 0 Downvote
Michael...you beat me to it!

Bevel the tube. This will give you the full thickness of the closure plate to prevent burning off the edges of the plate and having a crappy looking edge.

Yes...the bevel weld will provide a good "seal".
 
Upvote 0 Downvote
Hmmmn.

Well, what is drawn places the cover plate "inside" the end of the rounded-corner tube steel, right?

So, it will be easier to bevel the pate than the inside wall of the tube steel.

True - IF you were placing the cover plate over the end of the vertical tube, then I'd agree with you about beveling the tube steel walls. But as-drawn? By the way, the originalposter is going to have trouble getting the corners of the coverplate cut exactly and rounded off anyway - fitting a plate inside the end of the tube is very difficult.

Better/cheaper/faster. MOVE the cover plate so it is placed on top of the HSS piece. (The cover plate will need to be 1/2 bigger all around since the HSS walls are 1/4 thick. Then, after tacking the cover plate, the welder/fitter can grind off the corners of the cover plate to smooth the edges.
 
Upvote 0 Downvote
racookpe1978...exactly. Not easy to do as drawn. Too much fitup req'd.
 
Upvote 0 Downvote
There was another entire thread on this recently- do a search.

If all you want is a seal but little structural strength, you set the cap into the HSS, leave a root gap all the way around (using TIG wire to provide the space), use a magnetic fixture to hold the part until it's tacked, then simply buzz a MIG pass around the joint to provide the seal, grinding flush if necessary to make it pretty.

If you want structural strength, the simplest option is to set the plate in and deposit a FILLET around the ID. The plate will not be flush, but that may not matter.

If the plate needs to be flush and structural strength is required, then you're stuck with bevelling. Bevelling the ID of the HSS is very difficult- don't do it. Bevel either the OD and set the plate on, or bevel the plate. Which is more likely to be labour efficient and to give a good quality weld depends on what orientation the piece will be in during welding.
 
Upvote 0 Downvote
Thanks everyone! The HSS member is 20 ft long and it would be very difficult to fillet around the ID. (Even I knows that!) I have revised my sketch and asked a PJP @ the OD of the HSS member. The PJP I specified is 1/8". The plate will have the same size as the HSS OD and will be 1/4" thick. So the HSS will be 1/4" shorter than what I originally drew. I really appreciate everyone's input on this. Have a good Friday and a good weekend!
 
Upvote 0 Downvote
Umm, "set the plate in" means set it BELOW FLUSH from the end of the HSS, such that there's a place on the ID of the HSS to land the fillet...I'm not stupid enough to think you can find a tiny welder to climb into the HSS and fillet it from the inside...

The 1/8" gap PJP is fine as long as all you want is a seal, and if you can't tolerate the cap being below flush, i.e. on the top of a vertical column with exposed top where you don't want water to pond.
 
Upvote 0 Downvote
The way I've seen this done, is the end plate is slightly larger than the inside dimensions of the tube, the welder places it by hand and provides a couple of tack welds and then produces a fillet weld all around effectively sealing the opening.

Dik
 
Upvote 0 Downvote
Hi dik,

I didn't want a larger plate because I wanted flush edges and didn't want to cope the beam just to accommodate the plate. I would be curious though, from a labor standpoint, whether a fabricator would prefer to 1) fillet weld a larger plate and cope the beam top flange or 2) PJP a HSS-OD-shaped plate and install the beam as usual.
 
Upvote 0 Downvote
Hi Moltenmetal,

Ah ha on the "set the plate in". Thanks. The reason I wanted it to be flush is because I have roof deck to be attached to the top of column.
 
Upvote 0 Downvote
Status
Not open for further replies.

Similar threads

capntom62
  • Locked
  • Question
Finishing a 304 SS welded assembly
Replies
17
Views
122
EdStainless
EdStainless
DRJStruct
  • Locked
  • Question
Face Plate Welded to S-Beam 1
Replies
5
Views
72
dik
dik
Structural engineering EIT
  • Locked
  • Question
RISA connection Bolt Shear Strength
Replies
1
Views
126
DrZoidberWoop
DrZoidberWoop
MJCronin
  • Question
Quality of Welded fabrication from Transylvania - Can you help me ? 4
Replies
6
Views
135
dgeesaman
dgeesaman
metboss
  • Locked
  • Question
Welded v/s Single body Tubular Mandrels
Replies
2
Views
45
metboss
metboss

Part and Inventory Search

Sponsor

Back
Top