Nozzle locations in F&D Heads 2

[MJCronin]

To all,

For pressure vessels built to the ASME Code:

1) Is the location of nozzles in the "knuckle" region of an ASME torospherical (flanged & dished) head acceptable ?

This area, as I understand, is the weakest area of the F&D head.

2) Are there any limitations on the locations of nozzles in elliptical heads ?

( assume nozzles are oriented parallel to the axis of the vessel)

No opinions !!!!....... please be specific about your reasons and any references you may have.

Thank You

MJCronin

 

[deanc]

workermonkey

Strongly suggest you read the Forward of the Code. The Code is written the way it is for a reason.

Before you set the world on fire,you may wish to speak to a few old timers. Why don't you attend a Code meeting.

 

[GatorOne]

Amen to that deanc.

 

[MJCronin]

To GatorOne, workermonkey and deanc,

Remember me ? I am the one who asked, what I thought, was a simple question about an obvious issue........

I believe that "workermonkey" has made some valid points.....the best way to compare the text, format and intention of the ASME codes is to compare them with similar products from other organizations and countries.

While the ASME codes may not have been written by lawyers, the emotional and legal overhang of litigation from twenty years ago certainly "shades" most of the text that is written by engineers. As I recall, many years ago, the ASME was sued by a company that produced sight glasses of a type that was banned by the existing text of the code....this sucessful litigation prompted a code change as well as a "de facto" change in the tone and intention of all of the later code revisions later code.

My first personal gripe against the ASME codes is in thier convoluted format (where, for example in ASME B31.3, a paragraph refers to another paragraph which refers to a third paragraph !!) Other code writing organizations, such as API write simple straightforward rules and do not permit the kinds of options that ASME seems to favor....

My second gripe, lies with the "pontias pilate" attitude regarding important design requirements found in so many paragraphs. For example, ASME B31.1 requires the designer to design his pipe to mitigate vibrations, but refuses to provide any reference or methods to accomplish this. A second important example would be manways on tanks and pressure vessels. While ASME may mention thier need and importance as well as provide methodologies for design, API-650 simply provides a table with several sizes.

I agree with "workermonkey" and am getting out of this engineering field as I feel that it is going the way of the blacksmith.....there are fewer and fewer oportunities and the engineering competition is now in Mexico or India where $7.00 is a day's pay.....the retired elite will develop more convoluted rules and the inspectors will be paid far more than they should be.....

Couldn't ASME simply make a straightforward decision on nozzles in F&D heads ..... Like the Britts have managed to do ???


My opinion only

MJC

"People ask my why I do this, and I tell them that I have the heart of a small boy ... and I keep it in a jar on my desk." Stephen King

 

[GatorOne]

As in other walks of life, the more a person complains about an issue, the less likely that person has been involved in getting the issue fixed. I would imagine your opinion would be different if you had been involved in a vessel accident because your inspector or your "simple rules" did not inspect/design the vessel properly.
Pertaining the world economy, more power to offshore engineers if they can do the same work for less. Many companies have excellent pockets of expertise in the US that are very difficult to duplicate overseas.
Concerning PD5500 the recommended limit is 10% of the mean vessel diameter measured from the edge of the head.

 

[deanc]

MJCronin-so bitter? There was no desire on my part to incite
such an outpouring of emotion.

There was no clear cut(ASME)answer in your question. To do so would only be an opinion. Remember the more guidence there is,the more rules there are. How about the US nuclear industry? One needs to be safe yet profitable.

We deal in a industry where mistakes could cost people their lives. The engineer has the duty to prevent this,not the Code. The Code is only a minimum requirement for safety.

If one really gets in and digs the answers are there. The different Code sections are not that hard to use,but one must learn them.

It also appears that you have not had the opportunity to work with a really good inspector. This person will keep you out of trouble. They should not do your work. The AIA should be able to provide guidence in the questions that you have.

Overseas? This is true capitalism. We have no one to blame but ourselves.

Enough-I am rambling. Best regards to all.
deanc

 

[JoeTank]

This response is more to address the comments as to the make-up of the committees that maintain the Codes and Standards ASME and API... and not the knuckle head nozzle issue.

I am a member of both API (API-650, API-620, API-653 and to a lesser extent API-510 and API-579) and ASME (B96.1 and SBS)committees. Contrary to the many statements made herein, we are not lawyers, nor are we politicians. We are typically volunteer folks with a passion for our work. Most of us are engineers with careers in the tank and vessel disciplines, mostly from the oil and chemical industries.

I find it ironic that engineers are in charge of documents that require excellent wordsmithing skills. Most people would not think of selecting a technical geek-type for such activities. And yes, I have participated in revisions to the API tank and vessel Standards that required subsequent revisions due to poor wordsmithing. It never fails to amaze me that a group of adults can all look at the same proposal and agree that it looks okay... only to be shocked at how bad it looks when printed as an revision. But we fix it and move onward.

Thirty years ago I began employment with a tank and vessel fabricator. During my first week on the job I was given a copy of ASME VIII to review and update with all of the cut-and-paste colored pages. You older folks will remember that type of exercise. By the time I finished, I was totally confused by ASME VIII and convinced that I made a bad choice of careers.

I eventually came to understand that that there was some method to the ASME VIII format madness. For example, UG-28 deals with the design of cylinders for internal pressure. When originally written in 1923, cylinders were covered in UG-28. So, since 1923 one could always go to UG-28 to discover the Code rules for designing cylinders for internal pressure. That way one does not have to re-learn the Code organization every time a major revision is issued. During my career I have always had the benefit of being near a Code guru. If I was to ask where to find the Code rules for a particular topic, the guru would blurt out "go read UG-79". Gurus become gurus because the Code numbering system has been preserved.

Also, the Code inquiry system has benefitted from this approach. For example, if you have a Code question on UG-32, you can be assured that many other questions have arisen about the same paragraph. Hartford Steam Boiler maintained cross-refernce summaries of all past inquiries. It permitted the confused among us to read all of the inquiries ever written about UG-32. A great learning tool.

For those of you that are new to the ASME VIII world, hang in there, do you research and learn from the gurus that came before you. And, always remember that the Code is not a text book... never was and never will be. It was intended to be used by knowledgeable and experience hands.

Also, don't rely upon your AI as the sole backup for design adequacy. Most are not engineers and do not understand all of the critical non-pressure design issues raises by UG-22.

Ditto, regarding computer design program for vessel design. As a consultant, I have a lot of work come my way because someone relied upon the correctness of a canned computer program used outside its range of applicability.

Well, I guess I have waffled on long enough on this topic.






Steve Braune
Tank Industry Consultants

http://www.tankindustry.com

 

[GatorOne]

Very well put S. Braune. An important advantage of ASME is that it is a Code written by Users. Many of us introduce Code sections because we need them in our industries. Unfortunately many of us are also NOT English teachers when it comes down to the proper wording, clarity, etc.
A computer program is just a tool, same as a calculator or a spreadsheet. The designer still needs to know 'what's going on' for a safe and efficient design. The designer is still responsible for the design (good or bad) like it has always been.

 

[workermonkey]

wow, never thought i'd start this much of a debate. I think its just a little dissapointing to me as a new engineer that a lot of this stuff hasn't been taken care of. i know most engineers aren't english majors (myself included) but people have been using this stuff for years and its just seems that no one has gotten it right yet. Because i'm young, i'm still a optomistic that things can be fixed and that i should be pushing towards standardization in older industries such as the one i'm in (heat exchangers and tube products). I'm also not very keen on the idea of using a code that is designed for people who've been using it for years, not very helpful for people trying to learn it. come on, we're engineers people! these things should be easy for us to fix. nothing is impossible!

 

[deanc]

workermonkey:

No problem,this is one of the things I enjoy about Code work.

You will find there are a great number of people who feel there are not alot of problems with the Code. However you have avenues.

Join ASME,membership provides some good stuff. Read the Forward of the Code book. See Appendix 16. Take some Code specific classes. Check out the ASME and NB web sites. If your AIA has a web site check it. Talk to your AI.

Heat exchangers. Look at UHX-have fun. There are more changes coming.

 

[GenB]

MJCronin and workemonkey, Hi!
You are goood,
I see your advancement, please stick with what you have in the Code and do not complain. I get mad when I can not find the excemption needed and I certainly like to make my own.
Many Mfrs. have a saying in the Code changes just because they have a seat "insider" lobbying and it works, I see some changes and alowances done that way. they can only go so far as mostly design requirements have been allowed, not calculations or weld requirements.
In your case you can make it happen if you have the desire and time to seat in the several commitees for B&PV.
Or go to a more advance job in science, proffessor or so.
ER

Hey, I hear my kids fighting each other and call themselves
knuckle heads,
do you think that is it something to do with the Code?

one more Q= how do you check grammar in here?

 

[cab1990]

Very funny guys Steve, I hate to admit I chuckled at the cut and paste comment. I'd just like to add this one thread directed to the younger engineers. Todays struggle with this beastly code is tomorrows job security. It takes a while, so be patient. The gray hairs come quickly.

CAB