Enter the efficiency of the welded joint for shell sections with welded seams. This will be the efficiency of the longitudinal seam in a cylindrical shell or any seam in a spherical shell. Elliptical and torispherical heads are typically seamless but may require a stress reduction which may be entered as a joint efficiency. See Section VIII, Div. 1, Table UW-12 for help in determining this value.
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1.00 - Full Radiography
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0.85 - Spot X-ray
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0.70 - No radiography
The joint efficiency in this (and all other) ASME Code formulas is a measure of the inspection quality on the weld seam. In general, weld seams that receive full radiography have a joint efficiency of 1.0. Weld seams that receive spot radiography have a joint efficiency of 0.85. Weld seams that receive no radiography have a joint efficiency of 0.7. Seamless components have a joint efficiency of 1.0.
In addition to the basic rules described above, the Code requires that no two seams in the same vessel differ in joint efficiency by more than one category of radiography. For example, if circumferential seams receive no radiography (E=0.7) then longitudinal seams have a maximum E of 0.85, even if they receive full radiography. The practical outworking of this is that circumferential seams, which are usually less highly stressed, may be spot radiographed (E=0.85) while longitudinal seams are fully radiographed. This provides the same metal thickness at some savings in inspection costs.