Hi,

The seam between the shell and the head of a vessel should be computed in which element? For example, consider a vessel with two seamless heads and the designer choose to apply spot radiography. The longitudial and circunferential seam efficiency of the shell should be 0.85. In the case of the heads, the longitudinal seam efficiency should be 1.00 and the circunferential seam efficiency 0.85 or consider both 1.00?

Another example: In the case of a seamless shell with seamless heads, the circunferential efficiency of the elements should be 0.85 (for spot radiography)?

Thanks.

Hello Fabiano

The topic is dealt with in UW-12(d) and UW-11(a)(5)(b). Instead of talking about long and circumferential weld seams, we should rather think in terms of Category A and B welds. If the parts are seamless, and the circumferential (Category B) joint is spot radiographed, the head and shell thicknesses should be computed using a joint factor of 1,00. There is no need to calculate the parts using the Category B weld. It is only used when axial stresses are generated from wind and seismic loads.

[Ray Delaforce for Mandeep]

Thanks Mandeep,

But in cases where axial stresses must be considered, should I input 0.85 in the Category B joint?

If axial stresses are to be considered then the efficiency of the circumferential seam is 0.7 as the spot radiograph was used to design the head and shell to and efficiency of 1. There is an interpretation to this effect but I do not recall the number.

Regards,
EJL