Nozzle reinforcement pad thickness requirement
Nozzle reinforcement pad thickness requirement
(OP)
Hi,
I read in a Pressure vessel design manual and found out that the book states that
"Thickness.
While minimum thicknesses are given in Reference 1,
Section UG-IG(b), it is recommended that pads be not
less than 75% nor more than 150% of the part to which
they are attached."
I am just curious of the reasons behind it. Is it that if the reinforcement pad thickess is higher than the shell thickness, more stress will be on the shell ? What will happen if the thickness of the reinforcement is thinner than the shell thickness.
I read in a Pressure vessel design manual and found out that the book states that
"Thickness.
While minimum thicknesses are given in Reference 1,
Section UG-IG(b), it is recommended that pads be not
less than 75% nor more than 150% of the part to which
they are attached."
I am just curious of the reasons behind it. Is it that if the reinforcement pad thickess is higher than the shell thickness, more stress will be on the shell ? What will happen if the thickness of the reinforcement is thinner than the shell thickness.





RE: Nozzle reinforcement pad thickness requirement
Greatly thinner may have its perimeter so far out that is does not take up all of the nozz loadings. Remember ASME VIII Div-1 is "design by cookbook" and uses a lot of 'rules of thumb'.
RE: Nozzle reinforcement pad thickness requirement
If the pad is too thin and large it will be awkward, expensive and unsuitable for high temperature installations (as the vessel thermally expands, high local pad stresses will be developed)
If the pad is too small and too thick, it will present a "hard spot" that will cause high stresses as the vessel is pressurized
http://www.eng-tips.com/viewthread.cfm?qid=176764
http://www.eng-tips.com/viewthread.cfm?qid=201779
http://books.google.com/books?id=m6mLiGEGI7UC&...
MJCronin
Sr. Process Engineer
RE: Nozzle reinforcement pad thickness requirement