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.

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

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