Patches/Plugs/Seals Flashcards
Wrapping type seals must provide an acceptable leak rate for a minimum of _____ to confirm integrity prior to disassembly of internal seal.
30min
Can dewatering equipment be run continuously to establish an acceptable leak rate?
Yes. The personnel performing the internal repair SHALL be informed in writing that continuous educator operation is required to maintain acceptable leak rate.
Divers shall not leave the dive side until ______ is established, repairs are completed, or ships CO/esignated rep is granted.
double-barrier protection
What is the first reference drawing used when selecting stern tube seal?
Shafting arrangement drawing.
Un-stiffined flat patches shall be minimum ____ series aluminum, ____ mild steel, or ____ marine grade plywood.
1/4” 5000 series aluminum.
1/4” mild steel.
1” marine grade plywood.
Uncompressed gasket sealing material thickness shall be ____ inches.
2 inches.
All cofferdam applications must have a ______.
basic rigging plan.
All patches must have installed _____ or engraved serial number which corresponds to supporting documentation.
data plate.
Supporting documentation for a patch must include what 6 things?
Patch rated depth. Max hull opening size. fabrication drawing. Gasket requirements educator and vent line requirements, and patch specific hull opening requirements.
All cofferdam to vessel hull seal gaskets shall be made of what material?
Closed cell foam material.
Closed cell foam material shall conform to ASTM D 1056-00 Type 2, Class B or C.
Grade 1 or 2 for application up to ____fsw.
Grade 2 shall be used for depths deeper than ____fsw.
35.
In no case shall gasket width be less than ____.
3 inches.
Grade 1 gasket material has a ___ psi compression deflection.
2-5 psi
Grade 2 gasket material has a _____ compression deflection.
5-9 psi
Where hydrostatic force is the primary compression load; Gasket area shall be suitably apportioned to limit the allowable gasket compressive stress to ____psi.
50psi
Where rigging force is the primary compression load; Gasket area should be designed to provide a minimum compression of ____psi for gasket sealing.
3.5psi
Gaskets shall not be designed for _____ to be applied.
Shear loading.
Fasteners shall be either _____ or ____ ____.
Steel or Stainless steel.
All patches shall be sealed to the hull opening by a gasket compressed under _______.
Differential Pressure
For seachests and piping systems with no means of internal venting, the patch shall be visually inspected for what? How often?
The patch shall be inspected or reduced gasket compression. On an interval not to exceed 7 days.
Can you use a Brass Handle on mechanical expandable plugs?
Yes.
Plugs must be _____ ____ or equal.
Standard stock.
For a Seachest with no internal venting: Inspect how often? Or install?
Minimum 7 days, or install a 1 psi gauge resolution.
O-ring diameter stretch, during installation, should not exceed?
5%
What can be used to seal a DC Plug to the hull?
Sealing Compound (Bintsuke.)
For mechanical expandable plugs, the _____ rather than differential pressure secures the plug and forms the seal.
Expansion of the plug.
What appendix is the patch and plug installation sheet?
Appendix D.
In a patch, internal release of pressurized air when opening the valve indicates what?
Entry of water past the cofferdam seal, causing remaining air bubbles to compress.
Are tapered mechanical plugs authorized?
No, they tend to dislodge during the tightening process.
How do you remove a DC Plug?
Strike the sides with a hammer, or use a chisel.
Can you use a cheater bar to tighten a mechanical plug?
No
Are mechanical plugs with aluminum components authorized?
NO
When are divers authorized to leave the dive station?
When double valve protection is established, repairs are completed, or permission is granted by the CO or his/her designation representative.
Who signs the formal work package?
Repair activity & CO or designated representative.
What is I.D. on a mechanical expandable plug?
Inner Diameter.
Where can criteria for anode installation on ships and small boats operation in fresh water be requested from?
NAVSEA
What qualifies as “Double-barrier protection” when no diver installed plug is present?
Installation of an internal sealing blank and a closed sea-chest valve.
Patch and plug installation and inspection checksheets must be approved by whom?
CO (or designated representative) and the Repair Activity.
Prior to installation of a plug, the ship’s CO shall be notified of what?
Location of the plug and whether it’s a single or double valve protection.
Patch and plug checksheet shall remain where while the device is installed?
On file at the installing activity.
For mechanical plugs, what is the requirement for the top plate or washer?
Must be larger than the opening being sealed.
What is stamped on the end plate of each mechanical plug?
Size range. Can also be placed on a waterproof tag attached to the plug.
The plug must have a seated pressure rating at least how much ___ times the static pressure head it will seal?
1 ½ times.
If a Seachest has no means of internal venting, the patch shall be visually inspected by divers for what?
Gasket decompression.
An isolation valve for an internal vent shall be opened during inspection and observed for what?
The presence of water or rushing air.
After removing a plug, divers should remain for how long?
Until they receive word that no leaks exist.
When installing a plug, what needs to be cleaned?
Clean the hull surface and opening of any fouling, cleaning as far into the opening as the plug will reach.
For a DC wooden plug that is longer than ____ inches, it may need to be trimmed down so that a max of ____ to ____ inches protrudes from the opening.
8 Inches
3-4 inches
Where can information be found on a hull’s appendage (i.e. exact location and arrangement.)?
Docking plan
Patch and Plug INSPECTION checklist is what appendix?
Appendix C
What is the shim spacing on an unstiffened flat patch?
Max 5 inch shim spacing.
True/False A Zero Leak rate seal shall be confirmed at the internal repair area prior to removing piping fasteners?
TRUE
A patch rigging plan includes what?
Lifting requirements, securing and attachment requirements, manufacturer, and weight test requirements.
Uncompressed gasket sealing material thickness shall be what?
2 inches
All patch pipe nipples used to attach the suction side of dewatering eductors must have what installed to secure the space when dewatering is complete?
A valve.
Why are excessively long plugs not recommended?
They are harder to install, and pose a great risk to becoming fouled and dislodged.
During single-valve isolation, what must be rigged and operationally ready prior to commencing work?
Dewatering equipment, and an emergency plan must be in place to act the entire time single-valve protection is established.
Whenever single valve protection is in place, the repair activity shall include what?
A written notification, and a specific plan for immediate installation of a replacement piping component or internal sealing blank.
What if you are unable to achieve a “0 Leak Rate”?
A leak rate with dewatering equipment secured that is acceptable to personnel performing internal repair work must be established, as well as the ship’s DC equipment must be on hand.
When hull configuration limits the force applied by the hogging lines, the use of a _______ should be considered to provide the sealing force required.
Stand-off
What is the rubber in a mechanical expandable plug made of?
30 Durometer
Can an isolation valve for an internal vent be left continuously open?
Yes, if approved by the ship an internal vent may be left open to maintain cofferdam differential pressure.
What is the minimum PPE while making Binstsuke?
Glasses, heat gloves, faceshield, coveralls, leather apron, steel toed boots, and an ABC fire extinguisher. ←Look this up
How do you bleed off pressure to ensure a patch or plug has positive seal?
Open an installed bleed valve, or slowly loosen an internal flange. Only loosen, don’t remove.
If an internal blank has been installed, the integrity of the diver installed plug must be _________ prior to removing the blank. Plug seal integrity should never be assumed.
re-established/re-verified
If no other internal vent exists, the internal sealing blank shall have a _____ installed.
Less than 1/2 in diameter vent valve installed.
Supporting patch documentation must include what?
Patch rated depth, max hull opening size, fabrication drawing, gasket requirements, eductor and vent line requirements, and patch specific hull opening attachment and alignment requirements.
All patches shall be vented to atmospheric pressure by using what?.
An internal seachest vent, or an external non collapsible vent line.
A _______ MUST be installed and opened prior to operation of a dewatering eductor.
vent line.
When securing a patch to the hull, a temporary device such as a spider may be used to aid initial seating but ________ must also be used.
An additional means of securing, such as a hogging line.
If a __________temporary securing device is used as a positive attachment, a hogging line is NOT required.
a NAVSEA approved {temporary securing device}
