isentropic4
Mechanical
- Apr 30, 2009
- 1
I come from a Section VIII Div 1 background and now find myself in a B31.3 world. So far, so good. I've recently run across an issue that I request some opinions on.
I'm designing for Normal Fluid Service, no severe cyclic loading. I have a large blind flange from B16.47 with a 3" pipe inserted through the center of it, extending some length into the vessel (er, sorry, piping). It injects Fluid A into process fluid B. As B16.47 does not say anything about reducing flanges like B16.5 does, the presence of the hole in the center makes it unlisted. So per 304.4.1(b), I'm designing the blind flange as a flat closure per UG-34. No problems, the thickness of the standard blind is sufficient.
Now I have to do the reinforcement calculations. Para 304.4.2 says the total cross sectional area I need is defined in UG-39. The reinforcement I have available is defined per 304.3.3. Here's the questions:
1.) Is there any substantial difference between the opening reinforcement calculations for B31.3 and Sec VIII Div 1? (My ulterior motive is to buy software for this, and all the software seems to do Sec VIII reinforcement calculations in this situation).
2.) B31.3 says nothing about calculation of weld strength (UW-15, UG-41), it only says to refer to Fig 328.5.4D, Acceptable Details for Branch Attachment Welds, and size accordingly. Technically, this isn't a branch connection, its a pipe in a flat head that extends into the run pipe.
2a.) Does B31.3 require weld strength calculations anywhere?
2b.) Is there any sort of minimum thickness on the pipe coming through the blind flange as in UG-45?
2c.) As Fig 328.5.4D does not show any extension of the insertion pipe into the run pipe, is it permissible to use the weld material on the inside of the vessel as part of the reinforcement calculations (similar to Fig UW-16.1(l))? From a practical perspective, no one would consider extending a branch pipe into a run pipe so this situation might not have been officially considered. My hiccup is para 304.3.3(d) which specifically states that the reinforcement area starts at the inside surface of the pipe run.
Your opinions are greatly appreciated.
I'm designing for Normal Fluid Service, no severe cyclic loading. I have a large blind flange from B16.47 with a 3" pipe inserted through the center of it, extending some length into the vessel (er, sorry, piping). It injects Fluid A into process fluid B. As B16.47 does not say anything about reducing flanges like B16.5 does, the presence of the hole in the center makes it unlisted. So per 304.4.1(b), I'm designing the blind flange as a flat closure per UG-34. No problems, the thickness of the standard blind is sufficient.
Now I have to do the reinforcement calculations. Para 304.4.2 says the total cross sectional area I need is defined in UG-39. The reinforcement I have available is defined per 304.3.3. Here's the questions:
1.) Is there any substantial difference between the opening reinforcement calculations for B31.3 and Sec VIII Div 1? (My ulterior motive is to buy software for this, and all the software seems to do Sec VIII reinforcement calculations in this situation).
2.) B31.3 says nothing about calculation of weld strength (UW-15, UG-41), it only says to refer to Fig 328.5.4D, Acceptable Details for Branch Attachment Welds, and size accordingly. Technically, this isn't a branch connection, its a pipe in a flat head that extends into the run pipe.
2a.) Does B31.3 require weld strength calculations anywhere?
2b.) Is there any sort of minimum thickness on the pipe coming through the blind flange as in UG-45?
2c.) As Fig 328.5.4D does not show any extension of the insertion pipe into the run pipe, is it permissible to use the weld material on the inside of the vessel as part of the reinforcement calculations (similar to Fig UW-16.1(l))? From a practical perspective, no one would consider extending a branch pipe into a run pipe so this situation might not have been officially considered. My hiccup is para 304.3.3(d) which specifically states that the reinforcement area starts at the inside surface of the pipe run.
Your opinions are greatly appreciated.
