Lapping Metal Seats - Emerson Fisher ET Instruction Manual

Instruction manual (13 pages)

Table of Contents

ET Valve

November 2017

WARNING

To avoid personal injury due to leaking fluid, avoid damaging gasket sealing surfaces. The surface finish of the valve stem

(key 7) is critical for making a good packing seal. The inside surface of the cage or cage/baffle assembly (key 3), or cage

retainer (key 31), is critical for smooth operation of the valve plug. The seating surfaces of the valve plug (key 2) and seat

ring (key 9) are critical for proper shutoff. Unless inspection reveals otherwise, assume all these parts are in good condition

and protect them accordingly.

2. Remove the packing flange nuts, packing flange, upper wiper, and packing follower (keys 5, 3, 12, and 13 in figure

14). Carefully push out all the remaining packing parts from the valve side of the bonnet using a rounded rod or

other tool that will not scratch the packing box wall. Clean the packing box and the metal packing parts.

3. Inspect the valve stem threads and packing box surfaces for any sharp edges which might cut the packing.

Scratches or burrs could cause packing box leakage or damage to the new packing. If the surface condition cannot

be improved by light sanding, replace the damaged parts.

4. Remove the load ring (key 26) from an NPS 8 ET valve, or the cage adaptor (key 4) from any restricted‐trim valve

through NPS 4, and wrap it for protection.

5. On an NPS 6 ET valve with Whisper Trim III or WhisperFlo cage, also remove the bonnet spacer (key 32) and bonnet

gasket (key 10) on top of the spacer. Then on any construction with a cage retainer (key 31), remove the cage

retainer and its associated gaskets. A Whisper Trim III and WhisperFlo cage retainer has two 3/8‐inch‐16 UNC

tappings in which screws or bolts can be installed for lifting.

6. Remove the cage or cage/baffle assembly (key 3), the associated gaskets (keys 10, 11, and 12), and shim (key 51). If

the cage is stuck in the valve, use a rubber mallet to strike the exposed portion of the cage at several points around

its circumference.

7. For constructions other than TSO (tight shutoff) trim, remove the seat ring or liner (key 9) or disk seat (key 22), seat

ring gasket (key 13), and the seat ring adaptor (key 5) and adaptor gasket (key 14) where used in a restricted‐trim

seat ring construction. PTFE‐seat constructions use a disk (key 23) sandwiched between the disk seat and disk

retainer (key 21).

8. For TSO (tight shutoff) trim constructions, perform the following steps (refer to figures 6 and 7):

a. Remove the retainer, backup ring, anti‐extrusion rings, and piston ring.

b. Remove the set screws that lock the outer plug to the inner plug.

c. Using a strap wrench or similar tool, unscrew the outer plug from the inner plug. Do not damage the outer plug

guide surfaces.

d. Remove the protected soft seat seal.

e. Inspect the parts for damage and replace if needed.

9. For all constructions, inspect parts for wear or damage which would prevent proper operation of the valve. Replace

or repair trim parts according to the following procedure for Lapping Metal Seats or other valve plug maintenance

procedures as appropriate.