# Thread: Q:What is the maximum allowable wall thickness reduction ratio in the pipelines?

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## Q:What is the maximum allowable wall thickness reduction ratio in the pipelines?

What is the maximum allowable wall thickness reduction ratio in the pipelines?

Or in another way, how can I calculate the required minimum pipe thickness

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Here is info what you should care about when you assessing your pipelines:

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Much aprreciate it dear selmagis

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A formula in accordance with ANSI B31.3 "Code for pressure
piping , petroleum refinery piping"

T = Pido/2(SE+PiY)
Where
t = Pressure design thickness (in)
Pi = Internal design pressure PSI
do=Outside diameter of pipe (in)
S = Allowable stresses
E = Longitudinal weld joint factor, for seamless pipe = 1 and for ERW =
0.85
Y= Coefficient having values for ferritic steels as follows
0.4 up to and including 480C
0.5 for 510c
0.7 for 540c and above

(If you know original wall thickness of pipes)Calculation of minimum wall thickness of pipes based on allowable wall thickness reduction not more than 25% of original wall thickness

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Thanks dear khaled for your explination ,(Jazaka Alah Kaeran )