Rice Lake Weigh Modules/Mount Assemblies - Manual (Page 61)

3-9
VESSEL ATTACHMENTS Restraint Systems
Figure 3-6
Stay Rods
Stay rods are used to rigidly restrain a vessel in the horizon-
tal direction. These rods are installed horizontally in
tension between a bracket on the vessel and a bracket
attached to the vessel’s support structure or foundation.
Because of the negligible deflection of load cells under load,
the stay rods will have little effect on the accuracy of the
system when installed properly. It is necessary to install a
number of rods to restrict a vessel fully in a horizontal
plane; see Figure 3-5. On a circular vessel, the rods should
always be tangential. This prevents the vessel from shifting
in any direction, but leaves it free for thermal expansion/
contraction.
Figure 3-6 illustrates stay rods attached to a suspended
vessel. The rods must be horizontal so that they do not
affect the weighing accuracy. Fastening nuts are tightened
so the rod is snug—do not overtighten. This placement of
the nuts ensures the rods operate in tension and are never
subjected to a compressive or buckling load.
Stay rods are used to:
■
Improve system stability and accuracy by limiting
vessel oscillation or vibration.
■ Protect piping from fatigue due to constant vessel
movement.
■ Ensure the stability of tall slender vessels or vessels
with heavy eccentrically-mounted equipment.
■ Ensure the stability of vessels against wind, seismic
forces or threat from vehicular traffic.
■ Hold a vessel in place when mounted on canister cells.
These cells have very little tolerance of side forces and
must be loaded in the vertical direction only.
Vessel Restraint Systems
While many of the mounting arrangements offered in this guide are self checking, there are situations where additional vessel restraints
may be required to steady a vessel subjected to constant vibration, or to restrain a vessel from toppling or falling in the event of some
unforeseen circumstance. Two main types of restraint systems are stay rods and check rods.
Figure 3-5
When using stay rods to provide vessel
stability, they are most effective when
attached at or above the center of gravity of the filled
vessel. Stay rods should be made as long as practical,
as this will be beneficial in reducing forces in the vertical
direction. It should be emphasized that the rods must be
horizontal; for this reason one of the attachment points
should be adjustable in a vertical direction.
Caution