Rotary Subs 
Drill Collars

INSIDE B.O.P. DART VALVE

1. Break valve apart and visually inspect seat and dart for wear, pitting, or excessive use.
   

2. If pitting or wear is very minor, but valve leaks, you can lap seat and dart back to seal conditions. To properly lap seat and dart, chuck seat sub portion of valve in lathe. Use standard lapping compound, and lap seat and dart for good metal to metal seal.
   

3. If conditions require it, you may need to replace the seat, dart, spring, or all internal parts. To remove seat from seat sub, you must heat pin end of seat sub, to release tension on seat then knock seat out with removal tool and hammer. When replacing seat, heat seat sub again insert seat, tap it down, allow to cool for good shrink fit. If old seat cannot be removed with heat and hammer, you may have to chuck seat sub in the lathe and cut seal out. New seat and new dart must be lapped for proper seal to hold pressure.
   

4. Reassemble valve, pressure test, paint, and chart for use.
   

5. We recommend that the external and internal connections be inspected on a regular basis. Always perform inspection every time valve is repaired if possible.

WNCO VALVE Recommended Procedure for lapping of seat and Dart WN-2  15,000 PSI

METAL TO METAL SEAL INSIDE B.O.P. DART VALVE

1. Clean seat and dart as thoroughly as possible.

2. Chuck seat sub in lathe. Use a reasonable working R.P.M. to avoid injury or damage.

3. Apply lapping compound to seat area.

4.  Hold dart nose against seat area until metal seal is formed. It should create a slightly sticky pull or bond.

5. If it is necessary to machine the seat area to secure a good bond after lapping; be sure to cut the very same angle on seat as O.E.M. cut new (be accurate in you measurements).