Approximate Distance Between Flanges Discrepancy in ASME B16.5 & B16.47

[Dhanavel KUMAR]

Hi all,


I Have to know why we have not considered any approximate distance between flanges (RTJ) in ASME B16.47 ?

Below Mentioned point is my understanding so please let me clarify I am correct or not?

For Ring number R-93 to R-100 Depth of the Groove (E) is larger than Octagonal ring height (H) So, We don't need to consider any Approximate length over there. But, From Ring number R-101 to R-105 we have the clearance between Depth of the groove(E) and Octagonal height (H) is 0.16 mm. Maybe it will be compensated by tolerance of the Groove Depth (E). That's why in B16.47 was not talked about any approximate lengths.

My Question is about even we get some approximate length between flanges is 0.16 mm for below 24" flanges (Example : 2" Groove number 23, 600 lbs) but, here we have considered approximate length is 5 mm I don't know Why?

Please help me to know,

Thanks in advance,

Dhanavel KUMAR

 

[LittleInch]

I don't know why B16.47 doesn't supply this data in the same way B 16.5 does.

however your supposition is incorrect.

"For Ring number R-93 to R-100 Depth of the Groove (E) is larger than Octagonal ring height (H) So, We don't need to consider any Approximate length over there. But, From Ring number R-101 to R-105 we have the clearance between Depth of the groove(E) and Octagonal height (H) is 0.16 mm. "

If this was correct, the ring wouldn't actually seal the flange!!

Yes height H is smaller than 2 x dimension E, but the sides of the groove are at 23 degrees and start off only 0.8mm wider than the width of the gasket. The octagonal ring should never touch the bottom of the groove, but becomes wedged in the groove, hence providing the sealing forces. Note the small gap in the diagram below.

If you look at B16.5, the largest size (24") has mainly 6mm clearance up to class 900.

I would suggest somewhere between 6 to 8mm is used for B 16.47.

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[LittleInch]

A little bit of simple trigonometry gives 6.3mm separation for an R93 gasket (ignoring any compression of the gasket material)

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