ARI Armaturen STEVI 451 EN - Manual (Page 11)

Rev. 0040306000 0410 Page 11
Operating and installation instructions
3-way control valves - STEVI
®
450 / 451
7.1.3 Bellows seal design
If the stem leaks the bellows seal (pos. 20.3) is defective. The leak can initially be stopped
by tightening the screw joint (pos. 20.17) respectively the sleeve nut (pos. 20.16).
Stem and bellows (pos. 20.3) can only be replaced together.
Replacement of bellows seal:
- Remove actuator. (Refer to operating instructions for actuator!)
- Slacken screw joint (pos. 20.17) respectively sleeve nut
(pos. 20.16) by about one turn.
- Unscrew the bottom seat ring (pos. 2) (refer to point 7.2) -
with diverting plug version (Fig. 18, Fig. 19) not necessary.
- Unscrew hexagon nut (pos. 4 or pos. 60), (holding against spanner face).
- Remove plug (pos. 3 or 31).
7.1.3.1 Bellows seal and mixing plug
DN15-150
- Dismantle as point 7.1.3.
- Loose nuts (pos. 11).
- Detach bellows assembly (pos. 20).
- Loose nuts (pos. 20.8).
- Detach mounting bonnet (pos. 20.2).
- Extract stem-/bellows unit (pos. 20.3) from the bellows
housing (pos. 20.1).
- Drive pin (pos. 6) out with a drift.
- Unscrew stem adapter (pos. 37).
Note:
Adapter (pos. 37) and straight pin (pos. 6) are not existing at
DN40-50.
- Bolt new parts together, drill and pin them.
- Replace 2 gaskets (pos. 20.6) and 1 gasket (pos. 9).
- Assemble in reverse order.
(For tightening torques refer to item 7.3.)
- Secure with nuts (pos. 11 and 20.8) and tighten them
crosswise. (For tightening torques refer to item 7.3.)
- Tighten screw joint (pos. 20.17) gradually up to tightness of
the stuffing box packing (pos. 20.10).
ATTENION !
Refer to point 10.0 and 11.0 before dismantling the valve.
ATTENTION at DN125-150!
- Ensure that the torsion lock is correctly
positioned when inserting new stem/bellows
unit. Introduce the grooved pin (pos. 20.9) into
the torsion lock groove.
Make sure it runs smoothly!
Fig. 16:
Series 451 DN 15-150
with mixing plug