Pipe Pressure per ASME B31.1 (104.1.2)

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The pressure rating of comparable pipe material to fitting material.

Pipe Pressure per ASME B31.1 (104.1.2) formula

$$\large{ p = \frac{ 2\;S\; \left( t \;-\; c \right) }{ OD \;-\; 2\;y\; \left( t \;-\; c \right) } }$$
Symbol English Metric
$$\large{ p }$$ = pressure rating $$\large{\frac{lbf}{in^2}}$$ $$\large{Pa}$$
$$\large{ S }$$ = allowable stress $$\large{\frac{lbf}{in^2}}$$ $$\large{Pa}$$
$$\large{ t }$$ = wall thickness of pipe $$\large{ft^2}$$ $$\large{m^2}$$
$$\large{ c }$$ = allowable corrosion                    $$\large{in}$$ $$\large{mm}$$
$$\large{ OD }$$ = outside diameter of pipe $$\large{in}$$  $$\large{mm}$$
$$\large{ y }$$ = ASME B31.1, Table 104.1.2 (0.4 if temperature is less than 900°F)  $$\large{F}$$  $$\large{C}$$

values of y

Temperature °F900

and

Below

950100010501100115012001250

and

Above

Ferritic Steels 0.4 0.5 0.7 0.7 0.7 0.7 0.7 0.7
Austenitic Steels 0.4 0.4 0.4 0.4 0.5 0.7 0.7 0.7
Nickel Alloys UNS Nos. N08800, N08810, N08825 0.4 0.4 0.4 0.4 0.4 0.4 0.5 0.7

values of y

Temperature °C482

and

Below

510538566593621649677

and

Above

Ferritic Steels 0.4 0.5 0.7 0.7 0.7 0.7 0.7 0.7
Austenitic Steels 0.4 0.4 0.4 0.4 0.5 0.7 0.7 0.7
Nickel Alloys UNS Nos. N08800, N08810, N08825 0.4 0.4 0.4 0.4 0.4 0.4 0.5 0.7

Tags: ASME Standards