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rating of Flanges
2

rating of Flanges

rating of Flanges

(OP)
why rating of flanges 150# 300# 400# .what is the significance of these number.

And the significance rating numbers in socket fittings(3000#6000#), and threaded fittings(2000#,6000#)!

RE: rating of Flanges

What are "Ranks" used by military organizations?
It is just a Title with a written set of conditions and authority.
The higher "Rank" the more control, power, responsibility and capability.

Flange Ratings (and fitting ratings) are not all that different. They are just "Titles" given to groups of objects that have specific Design and Performance capabilities.

RE: rating of Flanges

Way back in ancient times (I'll leave the definition open, so as not to offend the more senior members of our community), they were relevant. However, materials changed/improved, the Standards changed, but the "titles" stayed the same.

RE: rating of Flanges

The titles now refer to a bolt pattern and flange thickness that haven't changed much in a very long time.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.

RE: rating of Flanges

The ratings for Classes of flanges -- 150#, 300#, etc. -- came from the MAWP in saturated steam service of the flange. And it was based on lower strength steel, and a higher Safety Factor. Thus an SA-105 Class 150 [150# in the old vernacular] flange has a current MAWP of 200 psig saturated steam 200# = 388°F].

But us 'Old Guys' still call it a "150-pound" flange.

RE: rating of Flanges

The socket-weld/forged threaded fitting Classes [2000, 3000, 6000, etc] are the approximate MAWP's at room temperature.

And a Class 3000 threaded fitting is made from a Class 6000 fitting bodies that has been threaded [vs. socket-welded]. The Class 2000 threaded fittings are 3000 bodies that are threaded.

RE: rating of Flanges

I had occasion this week to question the pressure rating of a 3000 class threaded fitting. Since I don't believe much that I read on the Interwebz, I purchased ASME B16.11. I had heard that 3000 class was the same pressure rating as ANSI 300 class flanges. Not so. Threaded class 3000 fittings are rated the same as Schedule 160 pipe (table 7). So in 2-inch at temperatures less than 100F, the rating of a 3000 class fitting is 4600 psig. Just goes to show that you shouldn't rely on rumors.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.

RE: rating of Flanges

"And a Class 3000 threaded fitting is made from a Class 6000 fitting bodies that has been threaded [vs. socket-welded]. The Class 2000 threaded fittings are 3000 bodies that are threaded."

Duwe6, I'm pretty sure that your statement quoted above is incorrect, although one could certainly make an acceptable 3000# threaded fitting from a forging intended for a 6000# SW presuming the socket ends are fully machined rather than partially forged first into the blanks. My opinion is based on observations of numerous properly marked threaded and socket welded 3000# fittings having the exact same exterior dimensions. The threaded 3000# fittings we receive routinely are not appreciably heavier than the SW ones at the same rating.

I don't have the standard handy but I'm pretty sure there are separate tables for threaded and SW fittings with different requirements for minimum wall thickness and hub diameter. I'm also again pretty sure from past evaluation that any 3000# threaded B16.11 fitting aside from perhaps a street elbow can have its female threads machined away to make an acceptable B16.11 3000# SW fitting, so that you can make SW x T couplings or threaded branch tees from the threaded versions for instance. I caution anyone to refer to B16.11 to confirm this first as it's again based only on my observation and recollection.

2000# fittings are a rarety here- we never see them because our local distributors don't stock them, any more than they stock the MSS 1000# forged analogs of 150# cast stainless threaded and socket-welding fittings: those too exist in a table somewhere but we've never seen one here.

RE: rating of Flanges

moltenmetal, you are probably right about forged 2000# threaded fittings and 3000# fittings comming from different specs and tables, BUT what I have received in the past, and am currently receiving from McJunkin are dimensionally identical. The mfr is using the same blank and same OD dies for forge 2000# threaded & 3000 s/w; and 3000# threaded and 6000# s/w.

The reason I got involved in this minutia is that a Purchasing Agent specified 3000# THREADED forged fittings, and we ended up receiving plumb-bob weights and bass-boat anchors. 6000# bodies are very thick and heavy, ignorantly so. I got the Purchasing Spec changed ASAP.

RE: rating of Flanges

Wow Duwe6- my experience with McJunkin is limited (they're not local to us, but to some of our customers), but what little experience I do have with them seems to match mine...

Our own local suppliers must be hungrier, because the 3000# SW and 3000# threaded fittings (both ordered as such) that we receive and stock have basically the same external dimensions (in the size range 1/2" to 2" which is all we use them in). They are nowhere near as heavy as the 6000# boat anchors you describe (which I've also seen- but only with the 6000# or 6M stamp on them). That's except for the SW reducing inserts, which pretty much look to be machined directly from bar from what I can tell, irrespective of rating.

I get to deal with this sort of minutia every day because we have no purchasing department- I buy my own materials for my projects. Fortunately, what I can get from stock locally feeds back into my specs, so we don't spec stuff we can't get quickly.

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