SPACER & BLIND Thickness Calculation for Internal Pressure (ASME B 31.3)

SPACER & BLIND  Thickness Calculation  for Internal Pressure (ASME B 31.3)

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Step1: Select the Spacer & Blind Material

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Step2: List Down

      Ø  Pipe Outside Diameter, (mm) = D

   Ø  Internal Design Pressure,(Kg/cm²) = P   

   Ø  Design Temperature, (C°) = T

For the material under consideration.

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Step 3: List down

Ø  Allowable Stress, (Kg/cm²)  = S

ASME B 31.3 @ Design Temperature.  (TABLE A-1)

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Step 4: Select

Ø  Joint Efficiency factor = E             (TABLE A-1A)

ASME B 31.3  (TABLE-1A)

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Step 5: Select

Ø  Corrosion Allowance, (mm) = c

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Step 6: Formula @ ASME B 31.3 

                                 3*P

tm   =    dg * √  (--------------)     +  c

                              16*S*E

tm= Calculated thickness including corrosion Allowance, (mm).

dg = Inside Dia. of gasket for RF/FF flanges or gasket pitch dia. for RTJ flanges, (mm).

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Step 7: Compare thickness

If      t > tm

t = Thickness as per API 590

Then selected thickness of Spacer & Blind is OK,

Else revise the thickness.

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