Stress classification for a Thick pressure vessel at central section
Stress classification for a Thick pressure vessel at central section
(OP)
A got a thick "Tee" component under internal pressure only, I would like to know how to classify the stress in a section where no influence of the of the gross geometrical discontinuity (the junction bend of the tee) is affecting the stress at the point where I am evaluating the stress.
Basically I can summarize my model as a simple thick cylindrical vessel, under internal pressure, my membrane stress in ok for the allowable stress I have, but there is a bending stress at the point (inside surface where pressure is acting) I am not sure how to classify this stress this last stress; if I classify it as a secondary stress Q my stress levels area ok but if I classify it as a Primary bending stress Pb my stress levels Pm +Pb are out after a stress linearization analysis.
In table 4-120.1 from Div 2, the first section describe:
(Component)-> cylindrical or spherical shell -> (location) shell remote from discontinuities -> (Origen of stress) internal pressure -> (type of stress) general membrane and "Gradient through plate thickness"(bending stress across the thickness???)-> classification membrane as Pm and gradient stress as Q.
Does any body can share opinions.
images SCL are from point B1 to B2
Basically I can summarize my model as a simple thick cylindrical vessel, under internal pressure, my membrane stress in ok for the allowable stress I have, but there is a bending stress at the point (inside surface where pressure is acting) I am not sure how to classify this stress this last stress; if I classify it as a secondary stress Q my stress levels area ok but if I classify it as a Primary bending stress Pb my stress levels Pm +Pb are out after a stress linearization analysis.
In table 4-120.1 from Div 2, the first section describe:
(Component)-> cylindrical or spherical shell -> (location) shell remote from discontinuities -> (Origen of stress) internal pressure -> (type of stress) general membrane and "Gradient through plate thickness"(bending stress across the thickness???)-> classification membrane as Pm and gradient stress as Q.
Does any body can share opinions.
images SCL are from point B1 to B2





RE: Stress classification for a Thick pressure vessel at central section
A primary bending stress can only be present in flat heads and flat walls (and in a few, quite rare, other cases).
To clearly understand the classification, you must answer the question: what happens with increasing load, when parts of the section go beyond yield?
The answer for a cylinder is that it would remain circular and straight, and the through thickness gradient would flat out: when rupture occurs, the stress is pure membrane, no more bending.
On the contrary a flat head would become a balloon.
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RE: Stress classification for a Thick pressure vessel at central section
If this is related to your post in thread794-278484: 2007 B&PV Division 2 Part 5 Secondary & Peak Stress Clarification, then your R/t ratio is way too low, and is covered by this rule in the NEW Division 2. (BTW, references to 4-120.1 are referring to, at the latest, the 2006 Edition of ASME Section VIII, Division 2. That's 4-5 years old technology. What is the reason that you are not using the latest/greatest technology out there?)
RE: Stress classification for a Thick pressure vessel at central section
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