Dimensions of Elbows 1

[rmillercwi]

Ive done a search and cannot find any standard for dimensions of forged elbows,tees, etc. I am thinking this is in ASME B16.11 but cant find that specification either (section 11?) I was refered to b16.9~b16.28 from a sa-234 spec under dimensions. Got lost from there.

The reason I am asking is my firm is looking into providing a service of monitoring FAC in powerboilers (among other things) and it would help greatly to be able to establish a baseline. From what I gather, there is no documented standardization of od dimensions of elbows and tees from manufacture to manufacture as there is for pipe?

Any help with this would be appreciated

 

[dbaird]

Go to:

http://www.pipingdesigners.com/Tools.htm

and download:

"Pipe and vessel data - all the piping info you need, without lugging the folders around, download and unzip"

David Baird

Sr Controls Designer
EET degree.
Journeyman Electrician.

 

[ytse]

I do not understand your problem.

Dimensions of Forged fittings are in ASME B16.11 (table 5), which included both end to end dimensions, OD and minimum wall thicknesses.

SA-234 is a spec for Wrought fittings, not forged fittings. Their dimensions are in ASME B16.9. OD of these fittings are same as that of pipe per ASME B36.10M.

 

[rmillercwi]

Perhaps I did not clarify to the letter. This afternoon I was in contact with a fitting manufacture and was given below explaination. I agree the tolarances for welding surfaces of fittings is clear. So are the main fitting dimensions of height, width, etc. The actual thicknesses (min. not included) are not and are not regulated per-se by any recognized standard. For example, look at any large bore fitting such as a LR 14" sch 160 elbow and compare to the pipe its welded to. You will find the elbow is significantly thicker than the pipe. The excess material is used to compensate for the thinning that occurs during the forming process to stay above the mandatory 12.5% max allowable reduction of minwal. To be safe, the suppliers will use thicker material prior to forming to compensate.

I was hoping to find a standard for this. The answer from the qc manager of mill was it is dependent on the manufactures ability to form. This thickness could vary as much as 20% from manufacturer to manufacture.

The answer to my question is that NO, you cannot determine the rate of internal corrosion/fac of formed fittings without first having a set of baseline measurements because you dont know exactly what the thickness is in the first place. Unlike pipe that has standard of thickness consistent the full length.

 

[JohnBreen]

More to the point there is no requirement for thickness in the Standard. These fittings are qualified not by calculated stresses based upon pressure and wall thickness but rather upon proof test. The Standard simply sets tolerance for basic dimensional end-to-end dimensions and some "squareness" tolerances. The thickness is determined by the manufacturer based upon proof tests - the test requires that if the fitting is attached to straight pipe (and capped or plugged) and hydrostatically tested to destruction the PIPE must burst (fail) before the fitting does. Various manufacturers have quite different geometries for their fittings and the external shape and thicknesses around the fitting will vary from manufacturer to manufacturer. Also, as stated, it can vary according to the manufaturer's ability to form - this means a manufacturer may make it thicker to assure it will be at least up to thier own minimum thickness standard. So no, the only way to get a baseline is to measure it with installation. The same applies to B19.9 wleding fittings.

Also, seamless pipe has a mill tolerance of 12.5 percent to accomodate the "wandering" of the tools (mandel and dies) during manufacture. Seam welded pipe will have the same standard thickness tolerance as the plate from which it is made.