is impractical or the access hole is required to be larger,
the cut. The final step is to cut the access hole using a
follow the steps required for new access holes. If you
cutting torch or other method.
must make the access cut larger or where more than two
REINSTALLATION OF THE PATCH.--After
multiple cuts and replacements have been made,
the equipment has been removed and new equipment
remove and replace the patch. Figure 13-54 shows
has been reinstalled, you will be required to reinstall the
patch removal involving more than two existing cuts
patch. If the removed plate is still usable, it should be
and some of the typical mistakes made while making
reinstalled. If the plate cannot be reused, cut a new
closure plate using the old plate as a guide. Determine
the weld joint design to be used and bevel the patch and
INSTALLING WATERTIGHT DOORS,
the bulkhead or hull to the required angle. Install the
HATCHES, AND SCUTTLES
patch in place and check clearance as required by the
weld joint design from MIL-STD-22.
As a shipfitter, you will replace numerous watertight
fixtures in your career. This is a relatively easy process
WELDING IN CLOSURE PATCHES.--
that involves no special skills. However, fixtures can be
Welding of closure patches should be done by certified
installed incorrectly if special precautions are not
welders and inspected by NDT personnel. Welding is
followed. When installing watertight closures, you
usually done using the block welding sequences to
should keep the following suggestions in mind:
reduce weld metal cracking. You would usually weld
the straight edges of the plate first and comers last to
allow the comers to expand and reduce stress. If you
Ensure the watertight door has been properly
are using a butt joint design, you must backgouge the
maintained before cutting out the door. Some
major problems with watertight fixtures are
welding process. This is usually accomplished after the
simply a lack of PMS and fixtures may not need
first side is completely welded or enough weld metal
to be replaced.
has been deposited to allow for backgouging.
Check the door and frame for warping.
Cutting Access Holes Involving Previously
Sometimes the door is warped but the
frame is straight. If the door is warped,
replace the door. If the frame is warped, it
When cutting access holes involving previously
must be cut out and replaced.
made cuts, cut in the center of the existing weld. If this
Figure 13-54.--Patch removal involving more than two existing multiple cuts.