Calculatorsโ€บSkillet Thickness
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Skillet (Paddle Blind) Thickness Calculator

ASME VIII UG-34 ยท Spectacle Blind ยท Line Blank

Paddle Blind Thickness per ASME VIII UG-34
Calculates minimum thickness for skillets (paddle blinds), spectacle blinds, and line blanks used for positive isolation in piping systems. Based on flat plate bending under uniform pressure per ASME Section VIII Div 1.

Design Parameters

psig
psi
Per ASME II Part D: S = SMYS รท 4 at design temperature
in

Formula (ASME VIII UG-34)

t = d ร— โˆš(C ร— P / S)
t = Min. Thickness (in)
d = Inside Diameter (in)
C = Attachment Factor
P = Design Pressure (psig)
S = Allowable Stress (psi)
C-Factor (UG-34):
0.13 = Bolted, gasket inside bolt circle
0.30 = Full-face gasket to edge
0.33 = Welded or integral edge

๐Ÿ“š Learn the Theory

Detailed guide to blind flange design per ASME VIII, flat plate stress analysis, and material selection for line blanks.

Read Engineering Guide โ†’

About This Calculator

Calculates minimum thickness for skillets (paddle blinds), spectacle blinds, and line blanks per ASME Section VIII UG-34.

Key Applications:

  • Paddle Blind: Solid plate inserted between flanges for positive isolation
  • Spectacle Blind: Figure-8 with solid/open sections that can be rotated
  • Line Blank: Temporary or permanent isolation per ASME B16.48

Common Materials:

  • A105: S = 17,500 psi (standard forging)
  • A350 LF2: S = 17,500 psi (low temp)
  • A694 F60/F65: High-yield pipelines
  • A182 F316: S = 16,700 psi (sour service)

Code References:

  • ASME Section VIII Div 1, UG-34
  • ASME B16.48 (Line Blanks)
  • API 590 (Steel Line Blanks)

Frequently Asked Questions

What is skillet (blind flange) thickness calculation?

Skillet thickness is calculated per ASME Section VIII Division 1, UG-34 for flat unstayed circular heads. The calculator determines the minimum required thickness based on design pressure, flange diameter, allowable stress, and corrosion allowance.

What ASME formula is used for skillet thickness?

The calculator uses ASME VIII UG-34 equation t = d ร— โˆš(C ร— P / S ร— E), where d is the flange inside diameter, P is design pressure, S is allowable stress, E is joint efficiency, and C is an attachment factor.

What is the corrosion allowance for a skillet blind?

Corrosion allowance is added to the calculated minimum thickness to account for material loss over the vessel's design life. Typical values range from 1/16 inch to 1/8 inch depending on service conditions.

When would you use a skillet blind in piping?

Skillet blinds (paddle blinds or spectacle blinds) are used to positively isolate process piping for maintenance, turnarounds, or to block flow in one branch of a piping system. They are sized per ASME VIII UG-34.

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Material Selection

Select pipeline and vessel materials based on service conditions, temperature.