Welds, minimum tensile strength

The minimum tensile strength for weld (qualification) and stress values shown shall be multiplied by 0.90 for pipe having an outside diameter less than 51 mm (2 in.) and a D/t value less than 15. This requirement may be waived if it can be shown that the welding procedure to be used will consistently produce welds that meet the listed minimum tensile strength of 165 MPa (24 ksi). 

In all cases, the strengths of the welds increase as temperature decreases and the elongations (with the weld at the center of the 2 in. gage length) generally remain about the same or increase as temperature decreases. These results also indicate that the minitnum strengths of welds in the nonheat-treatable alloys are the same as the minimum tensile strengths of annealed plate of the respective alloys. 

Not required for P-No. 3, 4, 5, or lOA materials (see Table 11.13) when weld throat thickness is 13 mm ( /zinch) or less, regardless of base metal thickness, provided that not less than the recommended preheat is applied, and the specified minimum tensile strength of the base metal is less than 490 MPa (71 ksi)... 

Base-metal P numberf Weld-metal analysis A numberf Material group Nominal waU thickness Minimum specified tensile strength, base metal Metal temperature range h/in, nominal wall Minimum time, b Brinell hardness, maximum... 

Base-metal P number Weld-metal analysis A number Base-material group Nominal wall thickness Minimum specified tensile strength, base met Minimum temperature ... 

Fu = Minimum specified tensile strength, PSI Fw = Allowable shear stress, PSI fb = Bending stress, PSI fw = Fillet weld size... 

Tensile tests were made at 75°F on all three groups of materials and at -300 F on two groups—the unwelded plate and the butt welded plate with the beads machined off-to determine the ultimate strength, yield strength and percent elongation. A minimum of three specimens per group for each test temperature was used. 

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