×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Blind thickness Calculation
2

Blind thickness Calculation

Blind thickness Calculation

(OP)
Is there a formula for calculating the thickness of a piping blind (i.e. Flange, Fig 8, line blind, etc) ? If so, what is the appropiate formula for each type?

Carlos

RE: Blind thickness Calculation

Hi Carlos,


Look at B31.3, paragraph 304.5.3:

The minimum required thickness for a blank shall be calculated by the following equation:

Tm = dg * ((3*P /16*SE) + c)^0.5

Tm = mininum required thickness
dg = inside diameter of gasket for raised or flat face flanges
dg = the gasket pitch diameter for ring joint and fully retained gasket flanges
S = the allowable stress from Appendix A
E = the weld quality factor See Tables A-1A and A-1B
P = design pressure (psig)
and the weld strength factor must be applied if there is a weld in the plate.

RE: Blind thickness Calculation

..........and

C = the corrosion allowance.  Also use "C" to allow for impingement abrasion or other wasting of the blank thickness.

RE: Blind thickness Calculation

Carlos,
       Just for clarity the formula given by John is for a line blind fitted between two flanges. It does not apply to a Blind Flange which is subjected to bolting moments.

RE: Blind thickness Calculation

To summarize, if the blind has bolting going through it, the most likely code to use is B16.5; if the blind is inside the bolt circle, the B31.3 formula may be applied. See also B16.48 which does the calc's for you based on the B31.3 formula. http://catalog.asme.org/Codes/PrintBook/B1648_2005_Line_Blanks.cfm

The B31.3 formula is based on the solution to the differential equation developed by Poisson a few years ago. Since the situation is actually highly nonlinear from both a geometrical and material perspective, the B31.3 formula is also quite conservative. More reading at http://store.asme.org/product.asp?catalog_name=Conference%20Papers&category_name=Design%20and%20Analysis%20of%20Piping%20and%20Piping%20Components_PVP2005TCK-3&product_id=PVP2005-71164

jt

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources