Design Pressure 1440 psi - Flanges S300

[Joss10]

ASME certified PV was built in 1959, max design pressure was 1440 psi, but most of flanges are S300 (ANSI B.16.5).
Maybe by that year flanges S300 could be used for different pressures than today (740 psi).
Any contribution to put light on this topic will be appreciated.

Note: see attached id. plate.

 

[TGS4]

What's your question/concern?

 

[Joss10]

The question is because the vessel could be operated @ 1440 psi as per id plate but the flanges were for 740 psi.

 

[pdiculous963]

In the 1957 Edition of B16.5, Class 300 carbon and low alloy steel flanges were rated for 720 psig at 100°F. Are you sure your flanges are B16.5 Class 300? If so, they were either calculated using Appendix 2 of Sec. VIII, or they are wildly undersized. Per the 1957 Edition, Class 600 flanges are good for 1440 psig at 100°F.

 

[LittleInch]

S300 was new to me - only one supplier lists it as a slip on hub type flange??

Why do you think they are class 300? - A stamp or have you checked dimensions?

Maybe the tank was designed for 1440a as a standard design, but only used for 740.

MAWP takes precedence?

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

 

[Duwe6]

This is a Code-stamped pressure vessel. Period.
The MAWP & MAWT are plainly stamped on the plate. Period.

Your speculations about the flanges are meaningless. If you really feel the need to reverse-engineer this Code vessel, you will need the U-1, the design calc's, and the design drawing(s). Without those, you are just guessing. BTDT.

 

[Joss10]

LittleInch,
Dimensions of flanges were duly checked as per ANSI B16.5, they are #300.

 

[LittleInch]

As these flanges are apparently slip on, all I can think is that the vessel is as designed,but then the nozzles being bits of pipe, for some reason, these flanges were added at a later stage after pressure test of the vessel.

You would need to find the original drawings to make sure but after 60 years, it is a miracle the vessel is still there never mind not corroded or fatigued out.

Why the query?

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

 

[Joss10]

LiiteInch,,
Vessel is in operation for longer @ low pressure, the owner wants operate it in higher pressure taking advantage of the statements in the ID about the design pressure. te About flanges, all of them are WN, we also think that original flanges were changed by those ones.
Finally, vessel is in good condition without evidence of any visible damage mechanism affecting it and no report of cracking or whatever similar.

 

[r6155]

Where are the actual as-built drawings and calculations?

Regards
R6155

 

[LittleInch]

Joss,

Still some odd issues.

You say that "most" of the flanges are S300. What are the rest.
You call them S300.Why? As far as I can tell the S stands for slip on.

What are the nozzles on this thing? Welded pipe with flanges on the end of the pipe?
Or flanges welded directly onto the vessel?
A picture or two would help!

In any event to use this at a higher pressure than you do now will need different flanges and a check on the entire system to find the lowest rated component. That's what gets you the MAWP of your system.

It would seem that the flanges don't match the vessel for some reason now lost in the mist of time, but an uprate of a 60yr old vessel needs more than a cursory visual inspection. Some UT wall thickness checks, a crack check on high stress locations and probably a pressure test are in order.

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

 

[moltenmetal]

As to your underlying question: no, under no circumstances would it be acceptable to operate a vessel with 300# flanges welded to it, at a pressure above the maximum rating of 300# flanges. Period. Full stop.

As to steps required to find out what MAWP might be safe for this vessel, with or without a flange replacement, you've been given good advice by others already.

 

[Christine74]

"This is a Code-stamped pressure vessel. Period.
The MAWP & MAWT are plainly stamped on the plate. Period.

Your speculations about the flanges are meaningless. If you really feel the need to reverse-engineer this Code vessel, you will need the U-1, the design calc's, and the design drawing(s). Without those, you are just guessing. BTDT."

Right... Because vessel manufacturers always comply with each and every one of the rules of the Code of Construction 100% of the time, just like Authorized Inspectors always check every single calculation without ever missing anything. Oh, and field contractors never make modifications to existing vessels without first obtaining all of the necessary approvals.


-Christine

 

[1gibson]

Maybe there was an investigation and it was de-rated, and swapped to 300# flanges so it would be obvious not to operate it at higher pressures. No report of cracking... No report of changing the flanges either, probably no reports of anything, that isn't a good sign.

What's the rest of the system rated to? Or in this case, maybe a safer question, what are the flange ratings?