Abstract: A housing (31) has cavities (32A), and a lance for locking terminal fittings (20) in the cavities (32A). A region of a lower wall (33) of the housing (31) forward from the lance (37) is formed as an open part (38). Thus, it is possible to make the entire lower wall (33) thin, and the housing (31) can be inserted into a smaller through-hole (19). A rib (39) projects between the open parts (38) of adjacent cavities (32A) and (32A) to increase a distance water would have to creep between the cavities (32A) and (32A). Therefore if a connector (30) is exposed to water, it is possible to prevent a short circuit between the cavities (32A) and (32A).

Abstract: A connection head at a connection end of a thick wall steel pipe has an outer end face formed as a truncated cone or a truncated sphere. A lower neck portion is formed at the rear of the connection head and has a cylindrical outer surface and a taper to the outer surface of the pipe. A connection washer covers the lower neck portion of the connection head. A shallow gently sloping annular groove is produced inside the connection head as a result of a press forming. The above structure can prevent fatigue fracture due to stress concentration at the annular groove inside the head and sticking of a nut to the washer due to excessive tightening torque.