- #1
thereddevil
- 26
- 1
I’m designing a subsea sensor that will go to a max depth of 600 m (6 MPa/60 bar). In a simple model, it will be made of a pressure housing cylinder and two end caps, all grade 5 titanium. Some geometry is attached.
I’m looking for advice on how to calculate the thickness of the cylinder/pressure housing based on the pressure. I’ve done some research and found a few methods:
1. ASME Section VIII – Division 1 (UG-28)
2. EN 13445-3:2009 Part 3: Design (Section 8 Shells under external pressure)
3. ‘Designing Under Pressure’ in the Journal of Ocean Technology Vol. 3, No. 1, 2008 (Link here: https://www.thejot.net/article-preview/?show_artic...) with two theoretical results:
a. Von Mises (same as first part of EN 13445)
b. Windeburg and Trilling’s Buckling Pressure
Failure mode I can see is the combination of external pressure on the cylinder with the buckling load caused by the end caps pushing inwards.
Now I’ve run them through with the methods above and have varying outcomes for the pressure at yield:
1. 7.8 – 2.4 MPa for different grades of titanium (grade 5 not listed)
2. 11.5 – 10.5 MPa
3. a. 77.9 MPa, b. 46.5 MPa
As you can see it varies a lot and not all good with a 6 MPa limit – what methodology do I use? Are these even correct? The last method (Journal of Ocean Technology) is interesting in that it explores adding factors to account for manufacturing defects (circularity for example).
Thanks in advance and happy to provide more info.
I’m looking for advice on how to calculate the thickness of the cylinder/pressure housing based on the pressure. I’ve done some research and found a few methods:
1. ASME Section VIII – Division 1 (UG-28)
2. EN 13445-3:2009 Part 3: Design (Section 8 Shells under external pressure)
3. ‘Designing Under Pressure’ in the Journal of Ocean Technology Vol. 3, No. 1, 2008 (Link here: https://www.thejot.net/article-preview/?show_artic...) with two theoretical results:
a. Von Mises (same as first part of EN 13445)
b. Windeburg and Trilling’s Buckling Pressure
Failure mode I can see is the combination of external pressure on the cylinder with the buckling load caused by the end caps pushing inwards.
Now I’ve run them through with the methods above and have varying outcomes for the pressure at yield:
1. 7.8 – 2.4 MPa for different grades of titanium (grade 5 not listed)
2. 11.5 – 10.5 MPa
3. a. 77.9 MPa, b. 46.5 MPa
As you can see it varies a lot and not all good with a 6 MPa limit – what methodology do I use? Are these even correct? The last method (Journal of Ocean Technology) is interesting in that it explores adding factors to account for manufacturing defects (circularity for example).
Thanks in advance and happy to provide more info.