What is different between Seal Weld and Fillet weld

[Thuhuongengineer]

Hi everyone,
I am not clear definition Seam weld.
AWS A3.0 SEAM WELD "“Any weld designed primarily to provide a specific degree of tightness against leakage". It mean that, Fillet weld can be Seam weld.

If any, Can you comparision between Fillet weld and Seam Weld.

 

[kingnero]

"designed for providing leakage" is the key phrase. Mind though, any seal weld is a weld that can (and probably will) react forces.
Which means you will likely have to deal with those forces, and calculate as it were a "regular" fillet weld.

 

[metengr]

It depends on the application for the weld. A full penetration seam weld can be used for structural loading or pressure retaining purposes, or in other words can be used for primary membrane stresses in components. A fillet weld can serve as a seal weld to prevent leakage or can transfer loads under tension and/or shear in service.

 

[kingnero]

There's a mistake in my previous post: it should read "designed for providing preventing leakage", as per the AWS definition.

 

[chicopee]

As kingnero second post pointed out is correct. A seal weld is a non-strength weld and you will see such weld on tube ends where they are either protuding or beaded thru the tubesheets of let's say boilers.

 

[pandithan]

Seal Weld is non -strength weld
kgp

 

[kingnero]

^^^ which doesn't exist.
as per my previous post.

 

[chicopee]

A seal weld root penetration is minimal unlike fillet weld. Also with a fillet weld, you will burn thru the end of the tube thickness but that should not happen with a seal weld, if done properly.

 

[kingnero]

... which will make it much more likely to fail, which is what I mean.

The entire structure needs to be designed in such a way that seal welds should not take up any forces. Because if they do, they will fail as they are typially not designed or executed to take up any forces.

I've seen much more seal weld failures as regular weld failures.

 

[gtaw]

Welded structures are monolithic. Once the load is applied, all welds will share the load whether by design or unintentionally.

All welds will produce residual stresses. The residual stress is on the same order of magnitude as the yield strength of the base metal. The residual stresses can be analyzed as vectors. Intersecting welds an easily produce residual stresses that exceed the tensile strength of the weld or the base metal and can result in cracks. The higher strength steels, those where the UTS/YS ratio approach 1, are more susceptible to cracking where there are intersecting welds.

The AWS structural welding codes for steel have minimum weld sizes listed as a function of the base metal thickness, not based on loading requirements. The minimum size requirement is to ensure the HAZ has no undesirable microstructures provided the minimum preheat requirements are met. These minimum weld sizes for fillet welds as well as partial joint penetration groove welds apply to seal welds.


Best regards - Al

 

[costes]

Hello, I'm new to this forum.

I would first of all differentiate between the terms seal weld and seam weld.

Back to the original question stated on this thread title: a fillet weld is applied to weld the joint while a seal weld is done to prevent leakage from the existing connection, usually a screwed connection. Hence, The seal weld is not ment to reinforce the existing connection.

 

[connectegr]

gtaw
I frequently see galvanized projects which require seal welds. However, I have never seen any consideration for the AWS minimum fillet weld sizes where these welds are applied. The seal welds are the minimum required to "seal" any seam of gaps in the faying surfaces. In most cases this is controlled by the diameter of the electrode. This is the first time that I have heard that the minimum fillet welds apply. My understanding is that the minimum welds sizes are intended to provided adequate fusion of the connected parts. While any weld will experience some stresses when loaded, seal welds are never considered in the design of the structural connection. I expect that the ductility of the filler metal and the relative stiffness of the primary welds will result in stress concentration in the designed welds. My experience is in the design of the structural connection and the intended load path, I have never considered any impact that may be associated to the seal welds. I am not familiar with any AISC or AWS instruction on this.

http://www.FerrellEngineering.com

Providing fabrication and erection efficient structural design of connections. Consulting services for structural welding and bolting.

 

[connectegr]

gtaw
After posting, I looked at AWS D1.1:2010, 5.14, and based on this wording I do agree with your post above. The minimum welds would apply to all fillet welds. But, I am at a loss to find more information in D1 related to seal welds. Re-reading a paper Duane Miller wrote, he also states that the minimum fillet requirements are necessary to insure weld quality and avoid cracks. In his words, ""It is only a seal weld", is often a precription for problems." As with most of our discussions, I differ Dr. Miller's instructions.

I had not given seal welds much thought from my connection designer's perspective. Thanks for the education.

http://www.FerrellEngineering.com

Providing fabrication and erection efficient structural design of connections. Consulting services for structural welding and bolting.

 

[connectegr]

This is a good reference. Thanks to gtaw, I search my binders of welding stuff.

http://www.FerrellEngineering.com

Providing fabrication and erection efficient structural design of connections. Consulting services for structural welding and bolting.

 

[gtaw]

That's why we frequent this site, to help each other. Glad I was able to participate and pass on the information that is useful. someone.

Best regards - Al

 

[Guest102023]

What is the difference between a harp seal and a fish fillet?

Seal weld refers to a weld's function. Fillet is a type of weld.

"If you don't have time to do the job right the first time, when are you going to find time to repair it?"