S0400-AD-URM-010/TUM Rev level: 07
G-2
j. Solenoid operated valves that fail shut, tend to seat with system pressure and do not have internal,
unisolatable bypasses may be used as barriers for maintenance performed downstream in the direction
in which pressure tends to seat the valve.
k. Unacceptable barriers:
(1) Do not use lift, swing, or stop check valves seated by pressure only unless the operator is
engaged to shut the valve (except as identified above).
(2) Do not use four-way valves (except as indicated in Appendix F, paragraph 3.d).
(3) Do not use feed regulating valves and other valves that are designed to allow leakage.
(4) Do not use solenoid valves other than those described above.
5. Barrier Isolation Protection.
a. To prevent inadvertent or accidental operation, or removal of barrier protection (e.g., valves, blanks,
locking devices, etc.), all barriers used for maintenance shall be danger tagged, except for check valves
identified in paragraph 4.d, and surface ship temporary hull fittings/blanks/flanges as discussed in the
note to paragraph 5.c below.
b. Disable and danger tag all valve control devices associated with the barrier valve. For example, if the
control valve or an actuator is electrically operated, remove and danger tag the fuses from the circuit or
disconnect and danger tag the electrical connector so that the control valve or actuator cannot be
accidentally energized. When removal of fuses or disconnection of electrical connector is not practical,
the use of a tagged-out switch is an acceptable means of isolation, except for the prohibitions in
Appendix F, paragraph 4.c.(1). If the control valve or an actuator is air operated, shut and danger tag
the air supply isolation valve so that the control valve or actuator cannot be accidentally operated by air.
c. For temporary hull fittings/blanks/flanges installed (waterborne or installed just prior to going
waterborne) outboard and used for maintenance isolation, a tether/lanyard will be attached to the hull
fitting/blank/flange, run topside and securely fastened topside. A test hose installed to a hull
fitting/flange may be used as the tether/lanyard for fitting/flange identification. At the topside
attachment point the tether/lanyard shall be labeled ‘Hull Fitting (Noun Name) Installed’. Ship’s Force
cannot independently verify by direct observation the correct installation of hull fittings/flanges or main
ballast tank blanks installed external to the ship and below the waterline. Tag-out of hull
fittings/flanges or main ballast tank blanks, below the waterline, shall be conducted as follows:
(1) After the hull fitting/flange/blank is installed and tethered, a danger tag shall be placed on the
tether.
(2) The identification label affixed to the hull fitting/flange/blank by the divers shall be used by
Ship’s Force and RA for tether identification.
(3) The danger tag shall indicate “____ hull fitting/flange/blank tether” or “____ Main Ballast
Tank blank tether”, as appropriate for system/component identification.
(4) The danger tag shall indicate “attached to ship” for position/condition of item tagged.
(5) Verify the hull fitting/flange/blank is on the correct hull penetration by venting the system
inboard if possible. If venting is not possible, some other method is needed to ensure the blank
is installed at the correct location (see reference (h)). When using a cofferdam, once the
system is vented, equalization should not be allowed, to prevent the cofferdam from loosening.
NOTE: The lanyard attaching, labeling and danger tagging of external temporary hull
fittings/blanks/flanges required by this paragraph (5.c) does not apply to surface ships if the ship and the
RA use WAFs per reference (h) to control the installation of the external fitting/blank/flange, the work
protected by the fitting/blank/flange, and the removal of the fitting/blank/flange.
d. Freeze sealing equipment shall be caution tagged to ensure that such equipment remains operational as
long as the freeze seal is required. Caution tags shall be used on freeze sealing equipment such as, but
not limited to, valves, compressor power supplies, quick-disconnects in piping or tubing, and other
equipment, which, if improperly or inadvertently operated, could result in freeze seal failure. The
freeze seal shall be danger tagged once established as a maintenance barrier.