the ability to install a leak-tight joint (i.e., though higher clearances
make installation easier, the dimensional mismatch makes the gasket
sealing more difficult);
fabrication tolerances of the vessel nozzles and wall nozzles (i.e.,
based on operating plant experiences at various facilities, a tolerance
of ± 1/16 inch is normally used in jumpers).
The vessel nozzle tolerances are determined by evaluating the tolerance
stackup of various components.
Handling . In contrast to normal piping installation where the construction crew is
able to guide the piping into installation positions, jumpers are placed into
installation position by a remotely operated crane. An accurate determination of
the jumper dead weight and center of gravity is performed, and the jumper lifting
bail is located appropriately. It is advisable to verify the balance of the jumper
prior to actual installation, because it may require additional counterweights to
achieve the balance.
Inherent flexibility of the jumper configuration is needed for proper jumper
operation. The slope of a process jumper is also important to minimize the
potential for contamination during handling. Maximum deflections are 1.5 inches
for process jumpers and 0.7 inches for electrical jumpers.
Pipe Stresses. Evaluation of jumpers includes determination of stresses and
deflections in the installed position as well as during handling. Handling stresses
and deflections are important because they impose a constraint on jumper
remotability. This is because a jumper with excessive deflection has a potential
for binding at the connector block. Also, handling stresses often suggest that the
pipe jumpers be stiffened by additional longitudinally mounted structural