Crane 410 ASME Class Adjustments to Tees, Bends, Reducers? 2

[steambuckets]

In Crane TP 410, they specify that you have to adjust the K factor for the pipe schedule with the associated ASME Class (p. 2-9 of the 2013 edition). Does this apply to tees, bends, and reducers? I don't think I have ever heard of a ASME Class for an elbow.

 

[LittleInch]

I don't think I have ever heard of a ASME Class for an elbow.

That's because it doesn't exist.

The wall thickness / ID is the same as the pipe.

Not sure how ASME class affects the flow though if you've already used the pipe schedule.

Can you post that section?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Latexman]

They are saying two things:
[ol 1]
[li]Use the internal diameter of each pipe and fitting to calculate it's individual K.[/li]
[li]Then, express all individual K's in terms of a one size basis K for the entire problem.[/li]
[/ol]

I'll add a third, if compressible flow, the one size basis for the problem should be the smallest internal diameter encountered in the problem, if all the diameters are about the same size. If size varies appreciable, break the system up into pieces for calculation.

Good Luck,
Latexman

 

[steambuckets]

So my confusion comes from the paragraph highlighted in the attached jpg. It says the values in the K Factor Table are based on a schedule of pipe associated with the designated ASME Class for valves and FITTINGS. The way I interpret it, the "fittings" group should encompass tees, bends, and reducers.

Referencing the example laid out in the following paragraph, if the pipe spec calls for schedule 80 pipe with Class 900 flanges, do you use the equivalent Schedule 120 velocity through an elbow as well as the valve? Or should you use the actual Schedule 80 velocity through the elbow since elbows do not have an ASME Class?

 

[1503-44]

The k values were obtained using the schedules shown. You should adjust those values for the specific ID of pipe walls that you are using. ignore references to class when calculating fittings, ignore references to schedule with flanges. In other words, use equation 2.9 for everything.

A black swan to a turkey is a white swan to the butcher ... and to Boeing.

 

[Latexman]

No .jpg attached.

When I look at our pipe specs for small diameter screwed fittings (tees, elbows, reducers, etc.), I do see ASME Classes mentioned, especially 3000 psi rating. For large diameter BW fittings, I see Schedules. So, yes, the "fittings" group encompasses tees, bends, and reducers some of the time. You need to look at your pipe specs closely.

Now, for Crane's example. Yes, use the Sch. 120 velocity thru Class 900 valves and fittings. However, in the real world, look at your pipe specs, so you know what is actually being used.


Good Luck,
Latexman

 

[1503-44]

Isn't that 3000 psi "working pressure rating", ie not "class".

A black swan to a turkey is a white swan to the butcher ... and to Boeing.

 

[Latexman]

Yes, it is a rating. I corrected the post. Thanks!

Good Luck,
Latexman

 

[GBTorpenhow]

Isn't that 3000 psi "working pressure rating", ie not "class".

Not fully relevant to the OP but this is a common misconception. See ASME B16.11 for how small diameter forged fittings (socket weld & threaded) in Class 2000/3000/6000/9000 are rated.

E.g. Class 3000 socket weld fittings are designed to be equally as strong as straight seamless Sch. 80/XS pipe of equivalent material. The actual pressure rating of a Class 3000 SW fitting will vary with relevant piping code, design temperature, material, corrosion allowance, etc.

 

[1503-44]

Good point. Since the dawn of piping history it has always been a source of confusion that B16.11 has no actual pressure ratings associated with its classes, whereas ANSI Class does.

A black swan to a turkey is a white swan to the butcher ... and to Boeing.