Maching Bar Stock Fittings
Maching Bar Stock Fittings
(OP)
If Astm B366 -S5.1 is required by the end user, then what is the concern:
Does this include both boring the I.D. and turning the O.D., or is maching prohibited with no exception?
What is the concern in fitting machined from bar stock and how does it differ from which are forged?
Does this include both boring the I.D. and turning the O.D., or is maching prohibited with no exception?
What is the concern in fitting machined from bar stock and how does it differ from which are forged?





RE: Maching Bar Stock Fittings
RE: Maching Bar Stock Fittings
RE: Maching Bar Stock Fittings
RE: Maching Bar Stock Fittings
Does this mean the fittings must be completely forged including the socket bore in socket fittings, or can it be forged and the socket depth be machined/bored out?
If forged does b366 -s5.1 mean that a final finish can not be obtained by machining?
RE: Maching Bar Stock Fittings
No, I wouldn't think so.
"or can it be forged and the socket depth be machined/bored out?"
Yes, that is how I have commonly seen forged fittings. You might buy a copy of the standard to be sure.
"If forged does b366 -s5.1 mean that a final finish can not be obtained by machining? "
I'd think a final machining step, at least for tube sockets, threads, etc., is a must.
RE: Maching Bar Stock Fittings
Ted
RE: Maching Bar Stock Fittings
diverdileo,
You will have to talk to the end-user to find out what their concern is about using fittings machined from bar stock.
The issue is rather clear; the end user has stated that he does not want fittings that have been machined from bar stock. If you want to find out why he has stated this, you will have to ask him. The intent is to forge them to "near net shape" and then finish by machining. I would assume the concern is, for some types of fittings such as elbows or tees, the forging process will direct the grain flow more in line with the direction of principal loading stress and that with a fitting machined from bar stock, you would not get this preferential grain flow. However, the end-user may have other concerns, as well. The only way to find out is to ask.
rp
RE: Maching Bar Stock Fittings
Mike Halloran
Pembroke Pines, FL, USA
RE: Maching Bar Stock Fittings
"B366 S5. Bar Stock Fittings
S5.1 Fittings machined from solid bar stock are not permitted."
RE: Maching Bar Stock Fittings
If bar stock is the concern what is allowed. Isn't bar stock forged stock that has been turned.
Isn't all stock other than cast forged in some way?
What is the concern?
RE: Maching Bar Stock Fittings
Isn't all stock other than cast forged in some way?
<<<
NO.
Mike Halloran
Pembroke Pines, FL, USA
RE: Maching Bar Stock Fittings
machines (upsetters), presses, rolls, and related forming equipment
Is bar stock made from the above definition?
RE: Maching Bar Stock Fittings
Redpicker has it right with "I would assume the concern is, for some types of fittings such as elbows or tees, the forging process will direct the grain flow more in line with the direction of principal loading stress and that with a fitting machined from bar stock, you would not get this preferential grain flow."
You could always call and ask your customer for an exception to the spec.
RE: Maching Bar Stock Fittings
Ted
RE: Maching Bar Stock Fittings
For a good example, go to the plumbing supply and look at a wrought copper tee. Typically, the branch is extruded out from the run by hydrostatic pressure, while the run is shortened, and thickened on the side opposite the branch. It's done inside a die so the resulting wrinkles are on the inside.
Mike Halloran
Pembroke Pines, FL, USA
RE: Maching Bar Stock Fittings
Drawing - A forging operation in which the cross section of a forging stock is reduced and the stock lengthened between flat or simple contour dies
and
Forging — The process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, "ROLLS", and related forming equipment.
So if my bar stock is hot drawn, then isn't it technically considered forged, so what is the concern with bar stock?
RE: Maching Bar Stock Fittings
You can argue semantics all you want, but my friends in the oil patch will send your crap back if they can't see a thick parting line.
If you are arguing this issue with a customer, and trying to use us to back your position, you will lose.
Mike Halloran
Pembroke Pines, FL, USA
RE: Maching Bar Stock Fittings
They have different properties, different welding characteristics, different grain structure, different machining properties, they smell different, and they taste different. No I am not kidding. When you machine and weld metals, they have distinct flavors and smells that permeate your senses, and when something is different, it's different!
I suspect that the argument is being made to your customer for the sake of cost?
It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.
RE: Maching Bar Stock Fittings
You have a legitimate point in that bar stock is wrought material (wrought meaning "worked from the cast state") and you can have a forged bar or a rolled bar and they will be essentially equivalent. However, the reason the supplementary requirement S5.1 exists is to make it clear that fittings machined from bar stock are not what the customer wants, in plain and simple terms.
Any attempt to make the meaning more percise, such as to define that amount of working required in each direction or to require a specific flow pattern would make the standard much more complicated so it would become 5 to 10 times longer. This would still not satisfy some people and they would want to change it more, doubling or tripling its length, again. You end up with a document with 20 to 50 times more pages, that is much more limited since only specific general shapes could be addressed, not to mention the number of manufacturers that would just refuse to manufacture to it without taking exceptions to the parts they didn't want to fool with.
The wording used in S5.1 makes it clear that bar stock cannot be used. It doesn't matter whether its a rolled bar, forged bar, or even a double vacuum-remelt centrifugally-cast HIP processed bar; if the customer has said he does not the fitting machined from a bar, then he doesn't want it machined from bar.
rp
RE: Maching Bar Stock Fittings
Often the reductions in rolling of bar stock are small and don't result in 'forging' the material. There is also no cross flow in rolling.
Forging will break up stringers and assure that you have sound metal.
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Plymouth Tube
RE: Maching Bar Stock Fittings
Having the grain flow in the right directions is desirable, especially for tees, elbows and flanges, but the minimum necessary criterion is that the material be of adequate homogeneous strength and without flaws.
As has already been noted, bar is commonly used for small fittings which suit round stock such as socket welding reducer inserts and swage nipples (the latter if you're foolish enough to specify them). Rather than stocking a myriad of sizes in umpteen materials, many local distributors stock bar and work with a machine shop to produce the required parts on a ~3 day turnaround. Saves them a bundle in otherwise dead inventory.