## Code ASME B31.4 - D/t ratio less than 20

## Code ASME B31.4 - D/t ratio less than 20

(OP)

[b]Clause 402.3 Stress From Internal Pressure[/b]

[i]For both restrained and unrestrained pipelines, the circumferential (hoop) stress due to internal pressure is

calculated as (U.S. Customary Units)

SH =PiD/2t

The above equation may not be applicable for pipe D/t less than 20.[/i]

Is there any reference or any code interpretation which formula to be used where D/t ratio is less than 20?

[i]For both restrained and unrestrained pipelines, the circumferential (hoop) stress due to internal pressure is

calculated as (U.S. Customary Units)

SH =PiD/2t

The above equation may not be applicable for pipe D/t less than 20.[/i]

Is there any reference or any code interpretation which formula to be used where D/t ratio is less than 20?

## RE: Code ASME B31.4 - D/t ratio less than 20

The equation below comes from section 6.4.2.1 of PD 8010 from British standards, where it recommends use of equation 4 for Do/tmin <= 20

The thin wall calculation is the same as ASME 31.4 so should be directly comparable.

Basically it looks at the mid wall diameter to take the Stress value as far as I know, but use the formula to be correct.

Remember - More details = better answers

Also: If you get a response it's polite to respond to it.

## RE: Code ASME B31.4 - D/t ratio less than 20

= = = = = = = = = = = = = = = = = = = =

P.E. Metallurgy, Plymouth Tube