Posted by: rafe
asme 31.4 is it necessary to mentione Design Factor - 04/20/08 03:01 AM
Hi
I am working on stress analysis for transportation lines and i m using ASME 31.4 .
While during stress analysis i found that my current system is having 95 % stresses of allowable when i used 31.4 and design factor 5.0.
When without making any changes in matrl, temp and etc i.e. keeping system as it is i found that system is passed with 80% of allowable stress while using asme 31.3
when i run system as it is while using asme 31.4 and without puting value of design factor then also system passed with minimum % of allowable .
My question is as per asme 31.3 & asme 31.4 , allowable stresses for asme 31.3 is less than asme 31.4, i.e.if i keep system as it is and i changed only from asme 31.3 to asme 31.4 then genearating stresses should be high but in my case its not showing.
Even when i m not mentioned design factoe in asme 31.4 then also allowable stress are same,(i.e. for with or without design factor) then why its showing different stress and forces values ?
Matrl. API 5L Gr B
Temp 212 Deg F
Press 150 psi
Allowable Stress for asme 31.4 with / without design factor
Expansion Stresses: 25200 psi
Operating Stresses: 31500 psi
Sustained Stresses: 18900 psi
Allowable Stress for asme 31.3
Expansion Stresses: 46954 psi
Operating Stresses: - psi
Sustained Stresses: 20000 psi
I am working on stress analysis for transportation lines and i m using ASME 31.4 .
While during stress analysis i found that my current system is having 95 % stresses of allowable when i used 31.4 and design factor 5.0.
When without making any changes in matrl, temp and etc i.e. keeping system as it is i found that system is passed with 80% of allowable stress while using asme 31.3
when i run system as it is while using asme 31.4 and without puting value of design factor then also system passed with minimum % of allowable .
My question is as per asme 31.3 & asme 31.4 , allowable stresses for asme 31.3 is less than asme 31.4, i.e.if i keep system as it is and i changed only from asme 31.3 to asme 31.4 then genearating stresses should be high but in my case its not showing.
Even when i m not mentioned design factoe in asme 31.4 then also allowable stress are same,(i.e. for with or without design factor) then why its showing different stress and forces values ?
Matrl. API 5L Gr B
Temp 212 Deg F
Press 150 psi
Allowable Stress for asme 31.4 with / without design factor
Expansion Stresses: 25200 psi
Operating Stresses: 31500 psi
Sustained Stresses: 18900 psi
Allowable Stress for asme 31.3
Expansion Stresses: 46954 psi
Operating Stresses: - psi
Sustained Stresses: 20000 psi