FORCE TO BREAK WELDED BARB

[valmeidan]

I am getting this made in China and they want to save cost and make two parts and welld them. it would be made from brass and fastneed with silver solder, they want to know the breaking force required to pass, and I am not sure of a reasonable force to spec. The part itself is screwed onto the end of a pump and then hose is attached and will have very little force on it at any time. I was thinking 30-40 lbs force but I am not sure.

 

[MintJulep]

4.23 Times stronger than if it has been made as a single piece.

 

[MikeHalloran]

Silver solder is not weld.

The proposed joint is very, very short. Application of a bending moment to barb, e.g. by a side pull on the hose, could produce some substantial stresses in the solder bond if the barb is thick enough to be rigid, and you could get more stress from distortion if the barb is thin.

We can't give you an answer here. You have to develop a set of load cases that represents the service the end part will see, like N gorillas hanging from the hose while it's aligned with the barb, and M gorillas hanging from the hose while it's bent at 90 degrees, and you have to consider the likely consequences of a failure.

Failing any of that, I'd want to at least verify occasionally that the silver soldered part is at least as strong as an integral part, regardless of how many gorillas pull the hose in any direction.



Mike Halloran
Pembroke Pines, FL, USA

 

[valmeidan]

I am going to try and simulate this with solidworks. The force on this is very minimal, as there is nothing hanging from this barb at all just a chlorobutyl tube connected to anotehr barb in a stationary assembly

 

[BUGGAR]

I suggest you consider shipping forces, especially if it ships from (and is mishandled in) China. Or else just make your sales before shipping.

 

[MikeHalloran]

there is nothing hanging from this barb at all just a chlorobutyl tube connected to anotehr barb in a stationary assembly

That's _now_. What happens in a year or two when the same part gets used in a different assembly, by someone else in your company who doesn't know that it might be less than robust?

I.e., I'd want it to be at least as sturdy as a roughly equivalent Swagelok part.



Mike Halloran
Pembroke Pines, FL, USA

 

[BUGGAR]

"I am getting this made in China and they want to save cost and..........."

What is the name of your company?

 

[mcgyvr]

"I am getting this made in China and they want to save cost and..........."

What is the name of your company?

"A Typical Corporation"

 

[tbuelna]

Find a different supplier. There is no way it will cost less to machine two separate parts, clean and prep the joint surfaces, assemble them in a fixture, apply silver braze, braze the joint, and then clean/inspect/pressure test the brazed assy, than it would be to machine the brass fitting in one piece. Even in China.

Not to mention the fact that a one piece fitting would be far more reliable.