reducer XS and SCH80 inner diameter 2

[Greg80]

Hello
I need to buy a Carbon steel concentric reducer 10/12" flanged.
My pipes are XS.
I need to have the same inner diameter.
What type of reducer should I buy XS or SCH 80 ?

Does anyone have the dimension table of reducers XS & SCH 80 which shows the inner diameter ?

Thanks

 

[sbnz]

Greg,
May be I am missing something - since both your pipes are Sch-XS, if you buy a con Red DN300x250, Sch-XS, it will have uniform 12.7mm thickness and have the same OD and ID at both ends to the connecting pipes - isn't it?

In cases where the thickness changes, I have used higher schedule for the reducers and transitioned one end as per code guidance (1 in 3 taper) to match the ID.

cheers,

 

[JohnBreen]

Greg80 and sbnz,

Actually, there are NO STANDARD WALL THICKNESSES for ANY B16.9 welding fittings including reducers.

B16.9 fittings are pressure rated by schedule of the adjacent straight pipe and the wall thicknesses typically vary along the length of the fitting. For ratings, these fittings are required to pass "proof tests" (or to be able to show that they can pass proof tests).

The idea is that if you are to place a schedule 80 reducer between two spools of straight schedule 80 pipe with B16.9 schedule 80 welding caps at the ends to close the pressure boundary and hydrostatically pressurize this assembly by increasing the pressure until there is a failure, the straight schedule 80 pipe MUST fail before one of the fittings fails.

Actually, there is not much that is "standardized" in B16.9 welding fittings. The end-to-end length is standardized and the "squareness of the ends is standardized. You will note that if you collect several 10 x 12 reducers from several manufacturers the shape of the cone area (and the cone angle) will vary according to that manufacturer's design. the radii of the knuckles will likely also vary. The manufacturer's design MUST have enough wall thickness AT ANY LOCATION along the reducer to pass the "proof test" (survive the "test to destruction"). So the manufacturer has great latitude in the design of the geometry and the wall thickness will vary according to the thickness required for the particular geometry.

Regards, John

 

[LSThill]

John:

http://www.bonneyforge.com/

http://www.bonneyforge.com/

 

[JohnBreen]

Leonard,

That is good information for that company's products but reducer wall thicknesses are NOT industry standard because there is NO industry standard for wall thickness along the length of a reducer. If the purchasing department buys ABC Company's products instead of the specified ZYX Company's products all bets are off.

John

 

[Greg80]

Thanks JohnBreen for your post,

If the thickness is not standard, so what's the difference between reducer schedule 40 and reducer schedule 80 ?
What type of test should be done ? hydraulic test ?
Can I order a reducer with a custom thickness ?

 

[KevinNZ]

You could get a reducer designed and rolled from plate. The design would be a pressure vessel code that the piping code allows.

A sch 40 fitting will burst before Sch40 pipe and a Sch80 reducer will burst before Sch80 pipe. Sometimes the mill will make then the same with just the butt weld prep to match the pipe sch.

 

[JohnBreen]

QUOTE: "A sch 40 fitting will burst before Sch40 pipe and a Sch80 reducer will burst before Sch80 pipe."

NOT CORRECT.

Please read ASME B16.9 By rule, the proof (pressure) test (as described above) assures that, for components all made to one schedule (all schedule 40 or all schedule 80) the straight pipe MUST burst before the STANDARD B16.9 fitting bursts.

If you fabricate a fitting from rolled plate (including required fabrication welding) for use it in a piping system, you will have created a non-Standard "non-listed fitting". You then MUST comply with the PIPING CODE that is mandated by the jurisdiction in which the piping system is to be built. If the ASME B31 Code for Pressure Piping, B31.3, Process Piping is the mandated piping Code, you should look at (and comply with) paragraphs 303 (and its sub-paragraphs), 304.6.1, 304.7.2, and others (look up "severe cyclic service". When you are designing a piping system to (e.g.) B31.3 you only go outside that Code when that Code directs you to do so (e.g., paragraph 304.7.2(b), 304.7.2(c), 304.7.2(d)). The exception is course is, you can always employ MORE RIGOROUS analyses methodologies for the analysis of individual components (e.g., non-standardrd fittings) using (e.g.) 3D FEA - assuming you have the loadings from your comprehensive beam model correctly applied).

Regards, John

 

[JohnBreen]

QUOTE Greg80: My pipes are XS

The NPS 10 XS pipe (it is also schedule 60) will have a NOMINAL wall thickness of 0.50 inch. The NPS 12 XS pipe (the wall thickness places it between schedule 40 and schedule 60) will have a NOMINAL wall thickness of 0.50 inch. These nominal wall thicknesses do not consider the mill tolerances etc. of ASME B31.3 paragraph 304.1.1).

QUOTE Greg80: I need to have the same inner diameter.

The B16.9 Standard requires the reducer fitting to be end-bored at the weld line to match the bore (nominal thicknesses) of the straight pipes (or other B16.9 fitting) that are welded to its ends. If you specify a schedule XS reducer it will reasonably match the schedule XS pipe it is welded to (remember that pipe is not really perfectly round and there will always be some amount of mismatch at the weld lines).

QUOTE Greg80: "What type of reducer should I buy XS or SCH 80 ?"

You should consider all the above and specify the reducer fitting accordingly.

QUOTE Greg80: "...what's the difference between reducer schedule 40 and reducer schedule 80 ?"

The ASME B16.9 schedule 80 welding reducer will have a higher pressure-temperature rating than the ASME B16.9 schedule 40 welding reducer, all other things being equal. Neither the schedule 80 reducer nor the schedule 40 reducer will be end bored to match you schedule XS pipe.

QUOTE Greg80: "What type of test should be done ? hydraulic test ?"

If you want to use a Standard ASME B16.9 12 x 10, schedule XS reducer, you will not need to further qualify the standard fitting (see B31.3, paragraph 303 General). If you wish to qualify a non-standard "non-listed" fitting, you should refer to B31.3, paragraph 304.7.2 for direction.

QUOTE Greg80: "Can I order a reducer with a custom thickness ?"

Probably not (assuming that "normal economics" prevail) as making one special fitting that complies with the standards would be very costly (remember that the end-to-end length is standardized by B16.9). You could have a reducer fabricated for you and have it qualified to the requirements of B31.3, paragraph 304.7.2 and that would also be very costly. In my 48 years in the piping engineering profession I have never seen (outside of research facilities) a design situation that could not be satisfied by using standard components.

Regards, John