Abstract: A Ni-plated steel sheet according to one aspect of the present invention includes a base steel sheet; and a Ni plating layer provided on a surface of the base steel sheet, wherein the Ni plating layer includes a Ni—Fe alloy layer formed on the surface of the base steel sheet, and a ratio of a Sn content to a Ni content in the Ni plating layer is 0.0005% to 0.10%.

Abstract: An improved coupling for a corrugated conduit includes a main tubular body with a sleeve defining a conduit receiving bore terminating at its inner end in an annular shoulder projecting radially inwardly of the tubular body. A nipple clamps the end portion of the conduit and is inserted together therewith into the conduit receiving bore where it is pressed forwardly by rotating a nut threaded on the sleeve for forcing the end of the conduit into pressing contact with the shoulder. The nipple is externally shaped to have a polygonal configuration so as to be slidably but unrotatably inserted in the correspondingly shaped conduit receiving bore, preventing the conduit from being twisted during the securing operation of rotating the nut about the sleeve.