Handling - hdbk1132990189

DOE-HDBK-1132-99

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

1.5.2

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.

1.5.3

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

members.

II-20