ASME Section 8 Div 1 vs Div 2 8

• Jul 12, 2003

2
• #2

prex

Structural

Jul 4, 2000

1,926

If you make an advanced search on this site by using Div.2 as the keyword you'll get a lot of stuff to read on the subject.
In short: Div.1 provides simple design rules at the expense of a heavier vessel, Div.2 requires more detailed calculations, making the design cost more but allowing higher stresses, so that, for complex or large vessels, the overall cost will be lower. Both, as any standard, try to keep low the industrial costs for different classes of vessels, still maintaining an acceptable level of safety.

prex

http://www.xcalcs.com

Online tools for structural design

 

Upvote 0 Downvote

• Jul 15, 2003

• #3

Davis224

Mechanical

Oct 31, 2002

3

prex's interpretation is correct. Also, be advised that Sec. VIII Div.1 is intended for pressures below 3000 psi; beyond that ' deviations from and additions to the rules apply' meaning compliance with Div. 2 is required.

 

Upvote 0 Downvote

• Jul 16, 2003

• #4

sgasociate

Mechanical

May 8, 2003

4

I think one of the most significant differences between Div 1 and Div 2 is Div 2 is used for cyrogenic vessels.

 

Upvote 0 Downvote

• Jul 17, 2003

• #5

SPLIT

Mechanical

Dec 21, 2002

57

Div 2 considers the calculations under fatigue conditions.Div 1 does not

 

Upvote 0 Downvote

• Jul 17, 2003

1
• #6

jte

Mechanical

Apr 8, 2002

2,357

Guys-

Division 1 may be used for cryogenic vessels.

Division 1 considers fatigue. See the previous threads where this was discussed in detail.

jt

 

Upvote 0 Downvote

• Aug 4, 2003

2
• #7

ReMan

Mechanical

May 30, 2003

3

Regarding the comment made on use of VIII-2 for cryogenic vessels, please note that the toughness rules in VIII-1 & VIII-2 are identical. Further, VIII-1 contains rules in Part ULT which are specifically written for vessels in cryogenic service.

RE: Fatigue Design - This is a great misconception regarding VIII-1 & VIII-2. Paragraph UG-22 in VIII-1 lists all loads that must be considered in design, including cyclic service. Just because VIII-1 does not does not provide mandatory rules for fatigue design does not mean that this loading condition can be ignored. Where mandatory rules do not exist, then U-2(g) applies.

 

Upvote 0 Downvote

• Aug 6, 2003

1
• #8

aclark

Mechanical

Feb 17, 2003

54

I think all of you are missing the most basic difference. The basic difference between section VIII Div 1 and Div 2, Div 3 is that Div 1 is a Code with design rules that are based on experience and Div 2 and 3 are based on design by
analysis.

In other words whe the Code was written it was well known that if you made a weld of a certian size it would give you satisfactory results. Also when Section VIII was origonaly written it had a safety factor of 5 it was lowered to 4 in the 1950's or 60's and was changed a few years ago to 3.5 and was given the term Design Margin.

 

Upvote 0 Downvote

• Aug 8, 2003

2
• #9

Hookem

Mechanical

Jan 29, 2003

96

Div. 2 are made for specific purpose, for specific location, and the vessel cannot be put into different service nor in different location without going through a recertification process.

I have spreadsheet for ASME Sect. VIII, both Div. 1 and Div. 2 Calculations. Perhaps I can share.......

 

Upvote 0 Downvote

• Aug 8, 2003

• #10

MarcoE

Mechanical

Oct 17, 2002

12

also, div 2 is for vessels 3,000 psi to 10,000 psi.
div 3 is for 10,000 psi and greater.

 

Upvote 0 Downvote

• Aug 8, 2003

• #11

jte

Mechanical

Apr 8, 2002

2,357

MarcoE-

Division 2 is by no means limited to vessels over 3000 psi. There are many, many vessels built to Div. 2 which have "ordinary" design pressures. I was heavily involved with one a few years ago which had a design pressure of 200 psi at 300°F. Just take a look a AG-100(a): "... The rules of this Division, taken as a whole, provide an alternative to the minimum construction requirements for the design, fabrication, inspection, and certification of pressure vessels falling within the scope of Division 1." It is an *alternative* to every vessel within the scope of Div. 1. Design pressure does not play a role in its applicability.

jt

 

Upvote 0 Downvote

• Aug 9, 2003

• #12

Tankman650

Structural

Feb 28, 2002

88

Calculations for Div 2 vessel must be certified by Registered Professional Engineer.

Div 1 does not have this requirement.

 

Upvote 0 Downvote

• Aug 10, 2003

• #13

juancito

Mechanical

Nov 30, 2000

64

Another difference between both divisions is the failure theory.
Div. 1 uses max principal stress menwhile div.2 uses max shear stress (Tresca).

 

Upvote 0 Downvote