Trunnion support check calculation 5

Refiew the following

COADE Pipe Stress Analysis Seminar Notes 2008 cost $250.00
Caesar II Suer Guide Trunnion • 12-6, 12-8

Vikoll

In the past we used whatever design/analysis methodology was available and we did not question the basis of the methodology. It was used "before" and so it was used again. There are better, more well understood methodologies now.

There is a "Kellogg method" for the design/analysis of support trunnions, dummy legs and base elbow supports that was documented many years ago. The document you would find the most helpful in discovering the "Kellogg method" is a series of Kellogg Company in-house design manual notes, "Subject 3810, Design of Piping Attachments - Cylindrical Pipe Attachments, Local Stresses" (13 pages), and Subject 5410,"Horizontal Trunnions" (7 pages). These have been traded around the various Internet discussion forums for years but recent evaluations of these old methods using finite element analysis have found them wanting.

The best approach to analyze these types of constructs is to employ finite element analysis techniques (FEA) by using a software product like FE/Pipe by Paulin Research Group.

Caesar II will serve you well for 90 percent of your piping analysis needs. Caesar II uses beam theory and the ASME B31 Codes for Pressure Piping (including the B31 stress intensification factors - SIF's) to perform structural analyses. However, there are some higher local stresses that B31 methodology and beam theory will not predict. In theses cases (e.g., trunnions and their attaching weldments) you will have to employ FEA to calculated the stresses and you will have to use the ASME B&PV Code, Section VIII, Division 2, to get the allowable stresses to use for comparison. While you are there (Division 2) have a look at the newly codified "structural stress" method of performing fatigue analyses.

Regards, John

John Breen (Mechanical)

Q)Question Trunnion support check calculation

A)Trunnion Calculation Sheet (attach)Technaical Note: Purdue University 1975.

There is a "Kellogg method" for the design/analysis of support trunnions, dummy legs and base elbow supports that was documented many years ago. The document you would find the most helpful in discovering the "Kellogg method" is a series of Kellogg Company in-house design manual notes, "Subject 3810, Design of Piping Attachments - Cylindrical Pipe Attachments, Local Stresses" (13 pages), and Subject 5410,"Horizontal Trunnions" (7 pages). These have been traded around the various Internet discussion forums for years but recent evaluations of these old methods using finite element analysis have found them wanting.

L S THILL

John Breen,
The well known Kellog Method was adopted into a British Standard publication (restricted distribution)some years back. I have seen many spreadsheets using the Kellog Methods which had interpreted the requirements/procedure incorrectly. For example not considering the total loading on a trunnion but simply checking each load independantly against the allowable stress. There must be a large number of trunnions out there in the wide world which produce stress levels in the pipe which theoretically exceed the Code allowable. It just goes to prove how forgiving steel is!!!

All,

"There must be a large number of trunnions out there in the wide world which produce stress levels in the pipe which theoretically exceed the Code allowable. It just goes to prove how forgiving steel is!!!"

Yes and also how conservative our allowable stresses are.

John

JohnBreen (Mechanical)


ADDITIONAL INFORMATION Pipe Trunnion Design


L S THILL

Trunnion stresses according to the Kellogg method and many other piping and stress engineering problems can be solved using 'Pipemill' software.

visit

Have a look at the reference used by Caesar for trunnions from elbows. I seem to recall that Budlong was also involved in a similar approach to trunnions from straight pipe. You will get high sifs on thin wall but at least there is some logic. The straight pipe trunnion was a code case or appendix of ASME III (Probably a bit of memory loss here - you will need to check).
You will get some extremely interesting results if you try to do FE calcs on trunnions and then compare them with Kellogg. You should try a single trunnion - header combination and then apply different loads / arrangements of the header. i.e. Not just a nominal few diameters of straight header with varying loads applied to the end of the trunnion. As DSB123 says "It just goes to prove how forgiving steel is!!!"

I would be wary of any "software solvers" (spreadsheets et. al.) until I knew exactly what equations they employ and where those equations came from. I would also like to see some comparison to FEA results and to ASME CC N-319-5 and the rest.

Not that it necessarily applies to any to the references above but questionable methodology is still questionable methodology even if it is automated.

John.

Because exactly the same reason, formulated by Sir John Breen above, I was wondering if it is possible to find any proven by time and commonly used by engineers reference materials (like mentioned above Kellogg Company in-house design manual notes with formulae and explanations from where these formulae came from, which I could use to develop project related spreadsheet and validate obtained results.
Does this method provide consistent results which is good enough for piping design objectives or it is worth time and efforts to do the check using FEA software?
What SIFs would you recommend to use in SAESARII for the trunnion and dummy support from the elbow?

Thanks and have a great day
Vikoll

John

See attach "I would also like to see some comparison to FEA results"

Also, ASME technical verification & validation for FE-pipe & Nozzle Pro. contact Tony Paulin.


Stephen




L S THILL

4Pipes..

Wen you say "Budlong" are you refering to Lynwood A. Budlong of Stone & Webster Engineering Mechanics fame...??

As I understand and recall, Budlong (and others) developed an in-house methodology and guideline on this particular topic that was eventually adopted by the USNRC.

I remember eating subs and chips on Boston Commons with Budlong....why....I even remember when he had hair !!!!

-MJC

MJC,
I would guess its the same person. Definitely Stone and Webster. It will be good to see what these guys are producing with current tools.