#33629 - 03/15/10 12:30 AM
Div2, Defining Allowable Stress Table 5a
|
Member
Registered: 03/15/10
Posts: 28
Loc: Malaysia
|
Hi all,
I got a query here, could anybody advise why PVelite & A.I. interprete that values from ASME II,D, Table 5a should be interpolate? It is a bit different from Table 2a which shown "exact" value compare with Table "5a" which shown "in range" value since mark "<" is there.
anybody share opinion please?
|
Top
|
|
|
|
#33647 - 03/15/10 08:35 AM
Re: Div2, Defining Allowable Stress Table 5a
[Re: Auwis]
|
Member
Registered: 01/02/03
Posts: 743
Loc: Houston, TX
|
Hello Auwis
I am not too sure what you mean. First of all, PV Elite uses the Imperial (American Units) tables from ASME Section II - Part D, not the metric tables. If the design temperature lies between two temperatures designated in Part D, PV Elite does a linear interpolation to get the desired allowable stress value. I am not sure what you mean by the statement: 'exact'.
_________________________
Sincerely, Ray Delaforce CADWorx & Analysis Solutions Hexagon PPM
|
Top
|
|
|
|
#33661 - 03/16/10 12:45 AM
Re: Div2, Defining Allowable Stress Table 5a
[Re: Ray_Delaforce]
|
Member
Registered: 03/15/10
Posts: 28
Loc: Malaysia
|
So sorry all if my word confuses you,
let me give an example:
From ASME II,D (Costumary, 2007) Table 5A, line 1 (SA 675-45):
allowable stress for: <40°C (mark "<" means below) = 103 Mpa <65°C (mark "<" means below) = 97.3 Mpa <100°C (mark "<" means below) = 94.3 Mpa Case 1: If my temperature is 65°C, we cant use 97.3 Mpa because (it was meant for below 65°C). Case 2: If my temperature is 80°C, should we just take value 94.3 Mpa? because it is meant to be for (65°~99°C) ?
Different from Table 2a; there is no mark "<", then we could interpolate it.
Opinion someone? Thanks.
|
Top
|
|
|
|
#33668 - 03/16/10 06:14 AM
Re: Div2, Defining Allowable Stress Table 5a
[Re: Auwis]
|
Member
Registered: 01/02/03
Posts: 743
Loc: Houston, TX
|
Hello Auwis
As I explained above, we use the Imperial Tables not the Metric Tables internally in our software. The two tables are different, and that is the source of so much confusion. Frankly, it is about time ASME abandoned the Imperial system and get in step with the rest of the world. In my opinion there is no point in duplicating everything.
_________________________
Sincerely, Ray Delaforce CADWorx & Analysis Solutions Hexagon PPM
|
Top
|
|
|
|
#33679 - 03/16/10 09:56 AM
Re: Div2, Defining Allowable Stress Table 5a
[Re: Ray_Delaforce]
|
Member
Registered: 03/15/10
Posts: 28
Loc: Malaysia
|
Hi Ray,
Nice to hear from you again. Thanx sooo much for ur kind reply. For the matter above, i believe i had get you confuse again.
I also agree on ASME should abandon the imperial system or make it generaly with properly shown with good conversion system. not simply round up or down which make everybody stick with their figures. ASME B16.5,2003 also another cases. I believe PVelite still stick with imperials.
Getting back to our topic, actually it is not a matter of conversion because both ASME II D metric & Imperial got Table 5a with metric system.
This is only the matter of ASME purpose putting mark "<" infront of the temperatures. Different from the way they show on Table 2a.
Really hope you are getting understood on what i explain.
sorry..sorry..sorry if my english are not as good as yours.
Thanks Ray..
|
Top
|
|
|
|
#33681 - 03/16/10 10:11 AM
Re: Div2, Defining Allowable Stress Table 5a
[Re: Auwis]
|
Member
Registered: 01/02/03
Posts: 743
Loc: Houston, TX
|
Hi Auwis
The ASME committee had a problem (of their own making) in that the temperatures in the Imperial table could not be properly matched with the temperatures in the Metric table. The whole thing is a mess. That is probably why they used the '<' symbol. They will continue to have problems until some strong willed person gets them to see the light.
I have used the metric system nearly all my life and I find it more logical and much simpler. To have a system that uses feet, inches and fractions of an inch is daft. The Imperial system completely messes up Newtons Second Law, and most of the time when using pounds in the imperial system, confusion reigns when dealing with weight and mass. That is a total catastrophe.
_________________________
Sincerely, Ray Delaforce CADWorx & Analysis Solutions Hexagon PPM
|
Top
|
|
|
|
#33812 - 03/22/10 11:18 AM
Re: Div2, Defining Allowable Stress Table 5a
[Re: Ray_Delaforce]
|
Member
Registered: 12/15/99
Posts: 600
Loc: Houston, Tx, USA
|
Auwis,
Where do you see the '<' marks in the printed allowable stress tables? I could not find it.
But, in my opinion it <= so you can 97.3MPa value for 65C. For temperatures between 40C and 65C you have to interpolate the allowable stresses at 40C (103MPa) and 65C (97.3MPa)
But, as Ray pointed out, PV Elite uses Imperial version of these allowable stresses. Because of rounding offs in the ASME code to get pretty looking values, these 2 versions are not exactly the same but very close.
But, if you refer to ASME Sec. VIII Div. 1 Appendix GG-1 (last line of 1st para in A-09) it allows the use of unit conversion constant with least 3 significant digits to convert from Imperial allowables to Metric allowables.
_________________________
Best Regards, Mandeep Singh CADWorx & Analysis Solutions Hexagon PPM
|
Top
|
|
|
|
#33823 - 03/22/10 07:34 PM
Re: Div2, Defining Allowable Stress Table 5a
[Re: Mandeep Singh]
|
Member
Registered: 11/12/06
Posts: 125
Loc: Ahmedabad, Gujarat, India
|
Mandeep, I think Auwis is looking properties in excel table from ASME Electronic Stress Tables. There is no "<" markes given for properties in the Sec II tables as said by Auwis. As Ray said, one need to interpolate between temperatures if your design temperature is not exactly matching with Code tabulated temperatures. Mukesh www.theculminates.com
|
Top
|
|
|
|
#34645 - 04/28/10 11:47 AM
Re: Div2, Defining Allowable Stress Table 5a
[Re: Mukesh]
|
Member
Registered: 06/04/09
Posts: 17
Loc: india
|
YES YOU CAN INTERPOLATE.. I WILL PROVIDE YOU SOME INPUT ASAP HOW IT ISALLOWED.
REGARDS MUKESH KALRA
|
Top
|
|
|
|
#34653 - 04/28/10 02:44 PM
Re: Div2, Defining Allowable Stress Table 5a
[Re: kalra]
|
Member
Registered: 01/02/03
Posts: 743
Loc: Houston, TX
|
I hope one day that ASME will go 100% SI Metric, and smell the coffee. They must forget thier former life in the dark ages.
_________________________
Sincerely, Ray Delaforce CADWorx & Analysis Solutions Hexagon PPM
|
Top
|
|
|
|
#35768 - 05/28/10 10:43 PM
Re: Div2, Defining Allowable Stress Table 5a
[Re: Ray_Delaforce]
|
Member
Registered: 01/15/09
Posts: 66
Loc: Malaysia
|
|
Top
|
|
|
|
#35780 - 05/30/10 07:28 PM
Re: Div2, Defining Allowable Stress Table 5a
[Re: SK Tan]
|
Member
Registered: 03/15/10
Posts: 28
Loc: Malaysia
|
LOUD & CLEAR Sir!.. I Missed out to check that note. .. Thank you very much for all the effort.
|
Top
|
|
|
|
|
0 registered (),
31
Guests and
0
Spiders online. |
Key:
Admin,
Global Mod,
Mod
|
|
|
|
|
1
|
2
|
3
|
4
|
5
|
6
|
7
|
8
|
9
|
10
|
11
|
12
|
13
|
14
|
15
|
16
|
17
|
18
|
19
|
20
|
21
|
22
|
23
|
24
|
25
|
26
|
27
|
28
|
29
|
30
|
31
|
|
|
12065 Members
14 Forums
16973 Topics
75151 Posts
Max Online: 303 @ 01/28/20 11:58 PM
|
|
|