Abstract: The failure factors of the crosshead and sliding sleeve on 3NB-500 drill pump were discussed in details in this paper. It was proposed strengthening the surfaces of the crosshead and slide sleeve to reduce wear and improve their service life. Oxy-gen-acetylene flame spray welding technique was selected to use for the strengthening treatment. PHNi60A+WC15% was tak-en as the strengthening material. The wielding technology was determined to obtain a spray welding thickness of 0.5 mm and the surface hardness is greater than 60HRC. In addition, the structures of the crosshead and sliding sleeve and the seal at the pull rod end were modified. The field application has indicated
that the strengthened and modified crosshead and performance was very good. And the wear between the crosshead and sliding sleeve was reduced greatly and the service life of the crosshead and the pull rod end seal are improved remarkably.

Key words: drill pump, crosshead, sliding sleeve, failure analysis, surface treatment