Abstract: A weldable vapor vent valve assembly comprising a heat-resistant valve body and a weldable connector portion fastened to an upper end of the valve body for welding onto the outer surface of a polymeric fuel tank. In one embodiment the weldable connector portion is overmolded onto an upper end of the valve body, with the mechanical connection and fluid seal between the weldable connector portion in the valve body strengthened by one or more sets of circumferential anti-leak ribs on the upper end of the valve body. In another embodiment the weldable connector and the valve body are manufactured separately, and the seal and connecting means for assembling the two in a fluid- and vapor-tight manner allow the valve body to be assembled to the weldable connector in a simple axial press-fit.