Machining Of Flanges From Forged Bar 2

[335den]

Is it acceptable, in any instance, to machine a 2" #600, 2 piece ball valve body from forged bar. The body has an integral ANSI B16.5 flange and the material could be any of the common materials e.g. carbon steel, stainless etc.
I am currently in the middle of an argument where i am stating that all flanges or components with integral flanges must be made from forgings (not forged bar) but i am being told as long as we inform our customer that we are using barstock and they accept it then it's no problem.
Any help on this matter would be greatly appreciated.

 

[BobBartlett]

It is my opinion that some round bar is a "forging". We regularly machine flanges from slabs cut from those forgings.

People like ABS have requirements on the amount of size reduction that is required for a bar to be considered a forging. That could be a starting point for "industry standard practice."

I suspect that you are accustomed to making your valves from "closed die forgings" that rough out the part.

The answer to your question may depend on how the specification or your sales literature reads. If it just says made from a forging, then machining the valve body from a forged bar would satisfy the letter of the law.

Having said all that, I hear your concern about customer relations.

I would proceed as follows armed with the fact that a forged bar is a forging.

I would call the customer and say, "Hey, your valves are going to be machined from forging stock in the form of a forged round bar -- as opposed to a closed die forging. This is allowed by the specifications, but I wanted to make sure you were aware of that. (you may add) We did this because a closed die forging would add 8 weeks and increase your cost by $1300 each valve. In the end, we decided that we should allow this decision on delivery and cost to be yours. Our technical department has taken the position that either route would produce an equivalent valve.

Gee, I guess that deviated from engineering, but your question kind of led us there.

To echo your concern, I just ordered some spray nozzles, and the vendor substituted alloy C-4 for alloy C-276 without asking permission. The literature will argue that C-4 is a more modern version of C-276, but he still had no right to do that without asking. He was just plain lazy. It required that I spend about a day and write 4 emails requesting a variance from my customer from the C-276 that he had previously approved. Would you like to know my feelings toward that vendor? If I ever needed another nozzle, I would buy it from someone else, or carve it out of solid metal myself before I ever did business with him again.

 

[moltenmetal]

335den: we routinely accept 2" and smaller ball valves made entirely from bar- flanges and all- and at classes higher than 600#. They are usually 3pc rather than 2pc. We do not require the bodies to be made from near-net forgings.

Presumably you do adequate flaw detection and the correct tensile measurements on the bar prior to machining.

As long as your sales literature is clear about what you're supplying, your customers shouldn't have a problem with that.

BobHartlett: if you asked for Hastelloy C-276 and were given C-4, you are right to be upset. If you asked for "alloy C", that's a different matter. As to which C alloy soup is the best one for the particular job, that's a question for the corrosion engineers. What I don't like is when people hard spec C-276 based on ignorance of the properties of the available alloys and then stick to that hard specification like glue. Some components, such as coriolis meter tubes, are available in Inconel 686 or alloy C-22 only- C-276 is not an option for whatever reason.