One of the most used and less conservative evaluation to perform flange check on external loads is the famous Kellogg Equivalent Pressure Method, where the axial force Fe and the bending moment Me are converted into an equivalent pressure Pe.If the sum of the equivalent pressure Pe and the flange design pressure at design temperature Pd is less than or equal to the flange pressure rating Pr at the design temperature, than the flange fulfils the requirements of Kellogg Equivalent Pressure Method.This method is very quick and typically is used on a large number of flanges during initial validation, but since this method can be deemed an over-conservative approach, normally there will be a large number of flanges that don’t achieve, and further analysis should normally carried out in accordance with ASME VIII.
Since equivalent pressure Pe is by far the quickest solution, many companies have tried to calculate if a correction factor could be applied to the equivalent pressure method to obtain more realistic results and so reduce the number of flanges to be verified in accordance with ASME section VIII.
The good news is that an official answer to this question has recently been compiled from ASME BPVC.
Based on Warren Brown works, one of the principal authors of ASME PCC – 1 “Guidelines for Pressure Boundary Bolted Flange Joint Assembly“, and author of many papers (41 papers on ASME website, mostly regarding bolted joints and flanges), the ASME code case 2901 has been recently issued.
This code case provide a less conservative formula to evaluate external loads on WN flanges chosen in accordance with Section VIII Div.1, UG-44 (b), (i), (j) or Section VIII Div.2 22.214.171.124 (a), (g) and 126.96.36.199.
The allowable pressure, that the sum of equivalent pressure Pe and design pressure Pd shall not exceed, is increased by a so-called “Moment Factor” FM, that depends on the flange pressure class and NPS:As an example for an ASME B16.5, 150# flange, Code case 2901 provides an FM, value = 1.2.
It should be noted that FM, is quite high for 150# flanges because the pressure rating formula for 150# is different from the formula used for higher ratings, thus the higher the pressure rating, the higher the flange diameter, the smaller the FM value.
A complete set of FM factors are available for download in Table 1, pag.2 of ASME BPVC Code Case 2901, which can be downloaded free of charge from ASME website, or at the link below.
ASME BPVC Code Case 2901
New and extended capabilities have been added to the latest version of CAESAR II, version 10.00 – 2018.
The software has been updated to B31.3-2016, EN-13480 (2016), B31.8-2016, B31.8 Ch VIII 2016.
Other piping and equipment codes support have been updated, like B31.3 Chapter IX (high pressure piping) and Kouatsu-Gas Hoan Kyoukai KHK level II seismic analysis.
Is now possible to identify supports, by using the new support tag field in the extended Restraint auxiliary panel, where two additional restraint definitions have been added. In this way all the six degrees of freedom of a support can be described in one single panel.
A tag hanger field has been added to the Hanger input list as well.
Very interesting is the Element name or in the Piping Input Window or in the Elements list input.
You can choose to show supports and hanger tags and element name in the graphic view.
Other two fields have been added to hangers and support lists, in order to read and import data from PCF files and to export through output reports and MDB output tables.
This topic will be discussed in the second part of this article.
A number of important enanchements in Piping Input:
- new find and replace function (in the right-click menu) added in the List dialog.
- when a pipe element in deleted is no more necessary to reset the coordinates
- is now possible to display the North arrow in both Classic Piping Input and Static Output Processor
- Previous and Invert options
- Added Mill Tolerance icon and new Mill Tolerance options
- When load cases are deleted in the Load case editor, the remaining load cases are renumbered after a windows shows the load cases and their dependents that will be deleted or revised.
Lloyd’s Register has created a Pressure Equipment Regulation map, that covers 70 countries/areas.
By clicking on any of the coloured countries and regions is possible to know what is the “country specific regulation governing the manufacture of pressure vessels, equipment and accessories, having a high level summary and the direct links to governmental websites of countries where available.”
This is a very useful tools to reduce compliance risks and expand in new markets.
As LR writes, since “requirements for a given jurisdiction change from time to time, you should always contact the regulatory body to confirm the accuracy of the requirements summarized” on what this knowledge map.
A deep knowledge of the local pressure regulations is a time-saving key-skill to stand in piping stress analysis engineering market.
Should you find some update to the regulation indicated on the LR map, feel free to add a comment or to contact LR.
LR Pressure regulation knowledge map
“Learn the basic designs, applications and details of metallic and fabric expansion joints using simple terms and a lot of visual aids.This webinar was created to explain the basic principles of expansion joints in the simplest way possible. The presentation will introduce you to expansion joints and concentrate on metallic and fabric expansion joints. It will explain the various designs, applications and details of each expansion joint using simple terms and a lot of visual aids. The presentation will conclude with general guidelines of the maintenance and ordering process.”
On Thursday, March 7, 2013 10:00 AM – 11:00 AM CST
Click here to register.
Intergraph has released the new version CAESAR II 2013 (Caesar 6.10) of his piping stress analysis software. This version contains updated versions of ASME B31.3, B31.3, B31.8, B31.9, and Z662 codes. Some codes have been issued just few months before Caesar, so Caesar II 2013 is not always updates at the last code’s versions. Continua a leggere
New version of ASME B31.3 has been issued.
In this version the table of Basic Allowable Stresses (A-1) has been totally revised. It has also been added a version with metric units (Table A1-M).
Also has been added the metric unit version of Table A-2 (Design Stress Values for Bolting Materials) and of the sample calculations for Branch connections (Appendix H).
Another change of B31.3 2013 is the Appendix N about Application of ASME B31.3 Internationally. Continua a leggere
“Where does mill tolerance come from?” Does the mill tolerance affects weight, Fy and sustained stress for B31.3?”, “What should be taken as a tolerance on plate? “, “What is the significance of “-12.5% Mill Tolerance”. “What if I check “all case corroded” in Caesar?”. These are samples of questions about mill tolerance found on forums.
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“Looks like fuel, smells like fuel, it’s not drilled from underground”, states Fiona Trott from BBC News. “The question is if this can be manufactured?”. This is the energy-related news more covered from media of the day. Let’s clean up the desk and try to understand.
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“How the stress engineers can save on input time and concentrate on their primary task of solving stress problems by extracting the piping layout directly from the plant model, and do so with full confidence”?
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