Civil Engineering Reference
In-Depth Information
Grit blasting of the remaining structural members was done in preparation
for welding
●
Final dimensions were measured to ensure that the new joints fit
●
New joints were installed.
●
All welds were inspected by magnetic particle inspection (MPI) equipment.
Other repair options considered included mechanical clamps and dry hyper-
baric welding. It was estimated that wet welding saved 40% and 60% of the
costs of dry hyperbaric welding and mechanical clamps, respectively.
7.12.6 Example: Platform
Repair
The platform consists of two 8-legged jackets (in 8 ft of water) that are con-
nected above water by a common deck structure and by horizontal braces.
In a large storm, the platform sustained several buckled members as well as
small cracks at several above- and below-water joints. Subsea survey found
small cracks in the bracing member that were identified by MPI. The damaged
members were repaired using traditional slip-sleeve replacement members. The
cracked joints were repaired using
“
Shear Pups
”
as shown in
Figure 7.38
,to
strengthen the joints. The shear pups consisted of 1/3 circumference pipe pieces
about 24 inches long that piggy-back on the brace at the joint in order to provide
an additional path for loads from the brace into the joint. The shear pups are wet
welded into place. The shear pups were considered a better repair than mechan-
ical clamps due to the complexity of the joint configuration, which made it
difficult to clamp. In addition, the cracks were small at these locations, were
identifiable only by MPI, or were only a few inches or less.
“
shear pups,
”
A
A
Sec. A-A
FIGURE 7.38
Shear pup.
Search WWH ::
Custom Search