Fillet Welds for Platform Clips Attached on Vessel

[lmacallndong]

According to client, sizing of fillet welds for nonpressure parts, like platform clips or pipe support clips, shall be based on UW-18(d). Is this correct?
"Unless the sizing basis is given elsewhere in this
Division, the allowable load on fillet welds shall equal the
product of the weld area (based on minimum leg dimension),
the allowable stress value in tension of the material
being welded, and a joint efficiency of 55%."

Client's basis is U-1(e)(2), which says,
"where nonpressure parts are welded
directly to either the internal or external pressure retaining
surface of a pressure vessel, this scope shall include the
design, fabrication, testing, and material requirements
established for nonpressure part attachments by the applicable
paragraphs of this Division"

I told client that sizing of fillet welds for platform clips should be per applicable structural or welding code like AISC or AWS, but client insists that ALL fillet welds on the vessel is in the scope of ASME Code. I told client the ASME has no rule on sizing of fillet welds for nonpressure parts. As far as I know, ASME only requires that weld for nonpressure parts be of weldable quality.

Is UW-18(d) used in sizing fillet welds for platform or pipe support clips?

 

[gr2vessels]

I'm sorry to break this to you, but the Client is right. Anything hanging off the pressure retaining component of a pressure vessel is subject of ASME regulations, including the sizing of the mentioned fillet weld. It also requires to carefully calculate the stress induced in the pressure retaining component by the non-pressure part welded (fillet weld of full pen) to it. The clip itself is a structural member calculated accordingly, but once is stitched to the vessel, is part of it, including the applicable vessel regulations.
Cheers,
gr2vessels

 

[SnTMan]

Plus, the client is the client.

Regards,

Mike

 

[lmacallndong]

gr2vessel,

I understand ASME requirements except for sizing of fillet welds. UG-55, UG-4(b), UG-22, UW-5(a) all support what you are saying. I am still not convinced about sizing of fillet welds or which weld allowable stress to use.

For example, a lifting lug is welded on the vessel. Material of lug and vessel is SA-516-70. What allowable load will you use in calculating fillet weld size? Are you going to use the allowable load mentioned in UW-18(d)? For SA-516-70 material, what would this allowable load be?

In the past, I normally use 9600 lb/lineal inch for E70XX.

 

[gr2vessels]

Ha, one more co-opted for the pressure vessel design. I believe the pressure vessel design is fascinating, absorbing and addictive. You are hooked...
In the pressure vessel design, the weld material is assumed same as the parent material, hence only the size of weld matters. In special cases, you might specify the allowable for the weld. That's another topic.
For details you have to refer to Appendix G of ASME VIII-1, which in turn makes reference to WRC 107 and WRC 297 for the design of lugs, clips, etc, including the weld size as part of support strength. ASME also allows you the use of British code PD5500 for the lugs and clips design. You might end up enjoying the FEA to design the lugs and clips, including the size of the attaching weld. Bednar book or even Dennis Moss book is a good start. Good luck.
Cheers,
gr2vessels

 

[lmacallndong]

Correction: 9600 lb/in is for E60XX.

SnTMan,
What do you mean by "the client is [bold]client[/bold]"? Do you mean to say that you will just accept everything the client says without even challenging them? Do you mean that right or wrong, I should blindly follow what the client says? I guess you're on the client side.

Whenever a client wants something without justification, they sometimes say, "I am the client and we are paying for your services and your product." This line of thinking is probably acceptable to other industries like say the food industry or in restaurants, but this attitude is not appropriate in the engineering industry. IMHO, this "I am the boss, you should ovey me." thinking is just a poor excuse for something the client wants but cannot explain why they want it.

 

[SnTMan]

lmacallndong, I am definitely NOT on the client side. I do not mean it is appropiate to blindly follow client requirements.

What I DO mean however is: The client has written a specification containing specific language about how he wants something done. Your company has apparently accepted this specification as a matter of contract. If so, you are obligated to comply. May execptions be negotiated after award? Of course. It is worth doing in a specific instance? Maybe, maybe not. Is it worth creating ill will with the client? Most likely not.

"This line of thinking is probably acceptable to other industries like say the food industry or in restaurants, but this attitude is not appropriate in the engineering industry." I do not agree. My company provides custom designed, custom built equipment. How about yours?

If I were in your position, and unless there were enough fillet welding to break the job, I would just do it. Pick your battles carefully, you are going to need goodwill from the client at sometime during the job, I'll bet. Be good to have it.

Regards,

Mike

 

[lmacallndong]

SnTMan,
You mentioned "The client has written a specification containing specific language about how he wants something done. Your company has apparently accepted this specification as a matter of contract. If so, you are obligated to comply."
I did not say that the fillet weld requirements for platform clips are in the client specification. It is not in any client specification, but client is citing the ASME Code for the said requirements.

I asked a very specific question on my original post and all I got are vague answers and opinion. I will repeat my questions. No need for explanations, just a simple answer of YES or NO.

1. Is the allowable load mentioned in UW-18(d) applicable to fillet welds on nonpressure parts such as platform clips, pipe support clips or lifting lugs?

2. Does UW-18(d) apply only to pressure parts?


3. Does ASME VIII-1 have rules on the allowable loads or sizing of fillet welds for nonpressure parts?

Thanks for the help and time.

 

[SnTMan]

"I did not say that the fillet weld requirements for platform clips are in the client specification", sorry, my error.

1. YES
2. NO
3. YES

Regards,

Mike