Piping Systems and Allowable Stress

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gabriel.rodel Active Contributor Join Date: Jan 2009 Location: Philippines Posts: 21	Piping Systems and Allowable Stress 08/11/2009 5:20 AM
	Guys the following data has been mentioned as a design requirement for a piping system; Design COndition : Pressure 550 psi, Temp 288 deg C. Material : A106 B Base on the above requirement, Can anyone tell me how to get the allowable stress using ASME Table 1. Is their any Factor of Safety requirement to determine the allowable stress.. Thanks a lot...
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#5 "Re: Piping Systems and Allowable Stress" by Abdel Halim Galala on 08/12/2009 2:18 AM (score 3)

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#7 "Re: Piping Systems and Allowable Stress" by Abdel Halim Galala on 08/12/2009 9:39 AM (score 1)

Dadz Active Contributor Join Date: Jul 2009 Location: Cavite, Philippines Posts: 10	#1 Re: ALLOWABLE STRESS REQUIREMENT 08/11/2009 6:13 AM
	Hi, With out other variables given, such as your fluid, velocity etc., 1.5 times is the common practise on factor of safety on your design. Regards.
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atorroja Associate Join Date: Mar 2009 Posts: 46	#2 Re: ALLOWABLE STRESS REQUIREMENT 08/11/2009 6:14 AM
	Service?
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atorroja Associate Join Date: Mar 2009 Posts: 46	#3 Re: ALLOWABLE STRESS REQUIREMENT 08/11/2009 7:18 AM
	ASME I? ASME B31 1? Asme B31 3?
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brkmech Commentator Join Date: May 2009 Location: UAE Posts: 80 Good Answers: 3	#4 Re: Allowable Stress Requirement 08/11/2009 8:53 AM
	YOU REFER TABLE A-1 OF ASME B31.3. __________________ RK
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Abdel Halim Galala

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Join Date: Feb 2007

Location: Cairo, Egypt

Posts: 1733

Good Answers: 248

Re: Piping Systems and Allowable Stress

08/12/2009 2:18 AM

The following table is subtracted from ASME B31.1 and B31.3, Table A-1, Allowable tensile strength, S, ksi of pipe material ASME A106 Grade B.

Notes.

1. The value of S can be interpolated.

2. You can use S of ASME B31.3 Process Piping, since it is applicable to be applied for all piping in any refinery, even for steam piping.

3. These values of S, including the factor of safety determined by the code, and that value shall be substituted directly into the code equation.

-20

100

^oF

200

^oF

300

^oF

400

^oF

500

^oF

600

^oF

650

^oF

700

^oF

750

^oF

800

^oF

850

^oF

900

^oF

950

^oF

1000

^oF

1050

^oF

1100

^oF

Specified Min. Strength

Tensile Yield

B31.1

(2004)

14.4

10.8

B31.3

(2004)

18.9

17.3

16.5

10.8

8.7

6.5

4.5

2.5

1.6

1.0

__________________
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gabriel.rodel Active Contributor Join Date: Jan 2009 Location: Philippines Posts: 21	#6 In reply to #5 Re: Piping Systems and Allowable Stress 08/12/2009 5:23 AM
	Thanks Abdel so basically we will use tensile stress and not the yield. Is it correct? In what particular case should i use yield stress?
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Abdel Halim Galala Guru Join Date: Feb 2007 Location: Cairo, Egypt Posts: 1733 Good Answers: 248	#7 In reply to #6 Re: Piping Systems and Allowable Stress 08/12/2009 9:39 AM
	No way to use the yield stress directly into the code equation. There is a factor of safety, and this factor depends on which code you fellow, since that factor of safety differs from code to another (ASME, JIS, BS, DIN, .. etc.), to the extent that through the single code like ASME there are different values for that factor of safety. And the clear example is that factor used in B31.1 is differs from that used in B31.3. And per ASME B31.4, the max. allowable tensile strength of the material S = 0.72 (E) (SMYS), where, E = joint efficiency & SMYS = Specified Min. Yield Strength. So, we have to select a max. allowable tensile strength S less that the yield strength Y, and may be S = 1/3 Y or 2/3 Y or may be 1/4 Y, ... etc. And that point of max. allowable strength S used by any code, must be located at the straight portion of Stress-Strain Curve, and the slope of that line represents the modulus of elasticity E of that material. __________________ It is better to be defeated on principles, than to win on lies!
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sv13 Commentator Join Date: Jun 2009 Location: Between India & Australia Posts: 71 Good Answers: 3	#8 In reply to #7 Re: Piping Systems and Allowable Stress 08/19/2009 12:42 AM
	Abdel halim, I often read your response with interest and a lot of credibility. Thanks for sharing your knowledge! __________________ Continuous Learning
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Abdel Halim Galala Guru Join Date: Feb 2007 Location: Cairo, Egypt Posts: 1733 Good Answers: 248	#9 In reply to #8 Re: Piping Systems and Allowable Stress 08/19/2009 3:36 AM
	Thank you sv13, you are welcome. __________________ It is better to be defeated on principles, than to win on lies!
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