A method of manufacturing a ball valve comprising: a metal tube, a ball member, a first annular valve seat, a first resilient seal element, a second annular valve seat and a second resilient seal element; wherein the method comprises: expanding a portion of the metal tube to form a first portion of the valve body, an inner surface of the valve body having a first conical portion and the remaining portion of the metal tube to form a first end of the ball valve; positioning the first resilient seal element on the first annular valve seat and the first annular valve seat against the ball member, the first annular valve seat sealingly engaging with the ball member and the first resilient seal element sealingly engaging with the first conical portion of the valve body; wherein the first annular valve seat is made of material comprising at least a first component for providing resilience; characterized in that the material comprises a second component for providing structural strength and the method comprises: positioning the second resilient seal element on the second annular valve seat and the second annular valve seat against the ball member, the second annular valve seat sealingly engaging with the ball member; and contracting a portion of the expanded metal tube to form a second portion of the valve body and a second end of the ball valve, the inner surface of the valve body forming a second conical portion, the second resilient seal element sealingly engaging with the second conical portion of the valve body. a metal tube, a ball member, a first annular valve seat, a first resilient seal element, a second annular valve seat and a second resilient seal element; expanding a portion of the metal tube to form a first portion of the valve body, an inner surface of the valve body having a first conical portion and the remaining portion of the metal tube to form a first end of the ball valve; positioning the first resilient seal element on the first annular valve seat and the first annular valve seat against the ball member, the first annular valve seat sealingly engaging with the ball member and the first resilient seal element sealingly engaging with the first conical portion of the valve body; wherein the first annular valve seat is made of material comprising at least a first component for providing resilience; characterized in that the material comprises a second component for providing structural strength and the method comprises: positioning the second resilient seal element on the second annular valve seat and the second annular valve seat against the ball member, the second annular valve seat sealingly engaging with the ball member; and contracting a portion of the expanded metal tube to form a second portion of the valve body and a second end of the ball valve, the inner surface of the valve body forming a second conical portion, the second resilient seal element sealingly engaging with the second conical portion of the valve body. positioning the second resilient seal element on the second annular valve seat and the second annular valve seat against the ball member, the second annular valve seat sealingly engaging with the ball member; and contracting a portion of the expanded metal tube to form a second portion of the valve body and a second end of the ball valve, the inner surface of the valve body forming a second conical portion, the second resilient seal element sealingly engaging with the second conical portion of the valve body.