Re: [PSUBS-MAILIST] Eurosub in the Americas

[Jon Wallace <jonw@psubs.org>]

Paul,

I'm not a metallurgist so can't speak for the use of other materials, 
however A516gr70 is the recommended material for pressure vessels.  If 
A516gr70 gets you safely to the depth you want to reach with physical 
dimensions that are manageable, the extra yield strength of S355j2 
serves no purpose and the additional legwork of trying to account for 
material properties becomes unnecessary.

Rather than attempting to match the material used by Emile upfront, I 
think a better approach would be to decide on the design depth you want, 
use the various calculators referenced in other mail to determine the 
physical dimensions of A516gr70 necessary to meet your design depth, 
determine whether those physical dimensions are reasonable to work with, 
and then decide if you need to find other material that has a greater 
yield strength.  Given the number of people who have used A516 for a 
variety of innovative sub designs I would be surprised if A516 didn't 
meet your requirements.  You can usually vary the thickness and ribs to 
get the desired overall design depth you want.

Based upon the charts Carsten provided as reference, it appears S355j2 
is equivalent to A572.  Here are some other pointers to compare A516 
against A572.

http://www.chapelsteel.com/pvq-sa516.html
http://www.chapelsteel.com/A572.html
http://www.a572steelplate.com/

A516/A516M
This specification covers carbon steel plates intended primarily for 
service in welded pressure vessels where improved notch toughness is 
important. According to different strength levels, the plates are 
available in four grades: Grades 55, 60, 65, and 70. The maximum 
thickness of plates is limited only by the capacity of the composition 
to meet the specified mechanical property requirements. The steel shall 
be killed and shall conform to fine austenitic grain size requirements. 
The mechanical properties such as tensile strength, yield strength, and 
elongation shall be determined by a tension test for the plates.

A572
This specifiation covers the standard requirements for Grades 42 [290], 
50 [345], 55 [380], 60 [415], and 65 [450] of high-strength low-alloy 
columbium-vanadium structural steel shapes, plates, sheet piling, and 
bars for applications in bolted, welded, and riveted structures in 
bridges and buildings. The alloy shall conform to the required contents 
of columbium, vanadium, titanium, and nitrogen. Permissible values for 
the product thickness and size is given. Tensile requirements (including 
yield point, tensile strength, and minimum elongation) and alloy content 
are also specified. General delivery and test report requirements are 
also cited.

Jon




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