A flow-control valve has an outer housing assembly including an outer housing member, a tube fixed to the member and having an inner end remote from the member, and an end collar of high-alloy steel welded on the tube end. An inner housing member is formed of nonferrous metal with an inlet port and an outlet port and a valve seat between the ports. The end collar is seated in the inner housing member and a valve stem has an outer end at the outer housing member and an inner end projecting into the inner housing member and guided in the end collar, extending through the tube between the members, and carrying a valve body sealingly engageable with the seat. A connecting sleeve engaged around and fitted snugly to the end collar and inner member has an outer ring of high-alloy steel welded to the end collar and an inner ring of nonferrous metal, fixed integrally to the outer ring, and welded to the inner member.