Question

A circular pipe of 1.5 m diameter is fabricated using a 16 mm thick plate in Fe 410 grade steel by lapping over and welding it using 8 mm shop fillet weld on the inside and outside of pipe as shown in figure.

The safe internal pressure that can be allowed inside the pipe is ________. (FOS = 1.5)

• A. $1.88N/m{m}^2$
• B. $1.97N/m{m}^2$
• C. $2.42N/m{m}^2$
• D. $3.42N/m{m}^2$

Answer 1

The correct option is A $1.88N/m{m}^2$

$\text{Size of weld}=8mm$

$\text{Effective throat thickness}=t_e=0.7\times 8=5.6mm$

$\text{Internal hoop force causing bursting of pipe}=\frac{p_{u}d}{2}$

$\text{Resistance offered by the weld per unit length of joint}=\frac{2t_e{f}_u}{\sqrt{3}{\gamma }_{mw}}$

$\frac{p_{u}d}{2}=\frac{2t_e{f}_u}{\sqrt{3}{\gamma }_{mw}}$

$p_{=}\frac{4t_e{f}_u}{d\sqrt{3}{\gamma }_{mw}}=\frac{4\times 5.6\times 410}{1500\times \sqrt{3}\times 1.25}=2.828N/m{m}^2$

$\text{Safe internal pressure}=\frac{2.828}{1.5}=1.885N/m{m}^2$