joint efficiency in the intermediate head attached to shell - UW-13
joint efficiency in the intermediate head attached to shell - UW-13
(OP)
I have some doubts about the joint efficiency in the intermediate head attached to shell indicated in the FIG. UW-13.1(e). According UW-13(c)(2): "The butt weld and fillet weld shall be designed to take shear based on 1.1⁄2 times the maximum differential pressure that can exist. The allowable stress value for the butt weld shall be 70% of the stress value for the vessel material and that of the fillet 55%."
1-I need calculated the head thickness using P=1.1/2 times the differential pressure and E=0.55 and the shell thickness using P=1.1/2 times the differential pressure and E=0.7?
2-It´s possible X-rayed fillet weld? Because in the table TABLE UW-12 indicate "Degree of Radiographic Examination" "NA"
If possible, when I use X-rayed 100% on the fillet weld and fillet weld can I used E=1?
1-I need calculated the head thickness using P=1.1/2 times the differential pressure and E=0.55 and the shell thickness using P=1.1/2 times the differential pressure and E=0.7?
2-It´s possible X-rayed fillet weld? Because in the table TABLE UW-12 indicate "Degree of Radiographic Examination" "NA"
If possible, when I use X-rayed 100% on the fillet weld and fillet weld can I used E=1?





RE: joint efficiency in the intermediate head attached to shell - UW-13
1) Calculate head thickness (as a seamless head or not, as applicable, E = what it equals) per UG-32 and UG-33, based on max differential P that can exist and which direction. Calculate shell thickness per UG-27 and UG-28, if applicable, using E as appropriate for seamless, Spot or Full RT of the long seam. Now size the two welds per UW-13(c). Capacities for each are given, each contributes its portion to the 1 1/2 dP requirement.
2) No, not likely. Fillet welds are generally considered non-radiographical, and use E=1 when needed. See Table UW-12 Type (7) & Note 5.
Regards,
Mike
RE: joint efficiency in the intermediate head attached to shell - UW-13
I´m studing a calculation sheet and the designer calculated the shell using E=0.55 and the head E=1. It´s correct? The weld calculation shall not be provided in the calculation sheet?
Thanks.
RE: joint efficiency in the intermediate head attached to shell - UW-13
RE: joint efficiency in the intermediate head attached to shell - UW-13
Using E = 1 for the head is probably right if the head is seamless. Using E = 0.55 for the shell implies to me it is lap welded. Yes / no?
Regards,
Mike
RE: joint efficiency in the intermediate head attached to shell - UW-13
The drawing is identical the sketch UW 13.1-(e). The required thickness for internal pressure is 6mm for external pressure 10mm and the actual thickness indicate in the drawing is 30mm. I think that the designer use this thickness, probable, for the weld strength, but nowhere in the calculation sheet it´s show the weld calculation.
Thank´s Mike for your explanation and pacience...
Regards,
Saulo.
RE: joint efficiency in the intermediate head attached to shell - UW-13
Roll and weld cylinder, spot RT of the long seam, E = 0.85. Required thickness for circumferential stress per UG-27(c)(1) = t(c).
Circumferential seam E = 0.55, as per UW-13(e), required thickness for longitudinal stress per UG-27(c)(2) = t(l)
Required thickness of the cylinder is greater of t(c) or t(l). Is this perhaps what your designer is doing?
I would think in this case, circ stress would govern as it most often does as 0.55 / 0.85 = 0.65, greater than 1/2.
Regards,
Mike