Changes Slab Gate (4)
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Transcript of Changes Slab Gate (4)
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WALWORTH NEW DESIGN SLAB GATE VALVES
DESIGN CHANGE
1. STEM
The supplier shall machine the top stem; they need to machine millimeter thread.
The purpose is to find easily the sweet point of the valve, as this way we ensure
the good tightness of the valve. Fig. 1
FIG 1. STEM
NOTE: Unifying the stem length used in the valves operated by gearbox and
hand wheel. The supplier needs to take as reference the major length. It will
avoid the future re-works when one valve needs to be modified of hand
wheel at gearbox.
2. DOWN STOP
The length of down stop shall be according table 1.
Its modification will make easy adjustment.
Table1. Length of down stop.
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SIZE Length of down stop
2 - 4 2
4 8 3
10 -18 4
20 - 30 6
30 42 8
FIG 2. DOWN STOP
3. YOKE
The supplier shall modify the yoke; it will eliminate the packing area according. See
figure 3.
FIG. 3 YOKE
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As result of this change we will reduce the damage on the stem for misalignment or
contamination by external agent like sand, craps etc.
NOTE: Its important to consider the rise face projection of the flange (bonnet
yoke) the purpose is to get the correct compression in the stem packing.
FIG. 4 RISE FACE PROJECTION
4. BONNET
The supplier will add the relief valve on the packing area. See figure 5.
FIG. 5 RELIEF VALVE
NOTE: THE SUPPLIER SHALL MEET WITH RTJ GASKET IN ALL VALVES
CLASS 600 AND ABOVE