A description of the temporary access closure or enclosure when required. (See Section 100.)
SECTION 072 SHOCK
The required grade of shock resistance shall be as specified herein. Omission of such indication does not relieve the contractor of the responsibility for determination of shock grades consistent with the capabilities indicated herein.
072c. Requirements for Non-shock Hardened Ships
Items intended for installation aboard operational non-shock hardened ships undergoing overhaul, modernization, or conversion shall possess shock resistance characteristics equal to those originally specified in the detail building specifications for the ship in question.
Therefore, the criteria for shock specified in the following paragraphs herein apply only to ships built to shock hardening criteria unless the specific intent of a SHIPALT, conversion or modernization is to include upgrade of a non-shock hardened ship to a shock-hardened status.
072d. Requirements for Shock Hardened Ships
Unless otherwise directed by the Supervisor, the following basic shock hardening criteria apply to overhaul, modernization or conversion of shock hardened ships:
(1) New shipboard systems, equipment, and foundations furnished for overhaul, modernization or conversion shall meet shock testing requirements and foundation shock design requirements specified herein.
(2) Where a system or structure is designated herein as requiring a grade of shock (i.e., grade - A, B), and the grade of shock specified conflicts with an individual ships detailed specifications, the ships detailed specification shall take precedence.
(3) The shock resistance of new shipboard installations shall not be purposely reduced to equal that of existing ship systems.
(4) Existing shipboard systems of shock hardened ships need not be upgraded to match higher shock resistance of later designs of shock hardened equipment or systems installed by SHIPALT, modernization, or conversion programs unless the upgrading of existing equipments or systems is a specific objective of the SHIPALT, modernization, or conversion.
Items designated as grade A or B, whose size and weight permit shock testing in accordance with Mil. Spec. MIL-S-901 shall be shock qualified by meeting the requirements contained therein.
Items requiring heavy weight shock testing in accordance with MIL-S-901 due to size or weight limitations shall be proven acceptable by shock testing aboard the Large Floating Shock Platform, Floating Shock Platform or Submarine Shock Test Vehicle, test facility schedules and other factors permitting. Test levels shall correspond to those of Mil. Spec. MIL-S-901.
Items which cannot be shock tested, and foundations for equipment which are required for performance of the ship functions specified, which cannot be included due to weight or size, shall be designed to withstand shock loadings. These loadings shall be established on the basis of dynamic analysis procedures outlined in publications NAVSEA 0908-LP-000-3010, "Shock Design Criteria For Surface Ships" and Design Data Sheet DDS 072-1, "Shock Design Values" (CONFIDENTIAL).
In general, items to be resiliently mounted shall be shock-tested while installed on the same type of resilient mountings, including buffers (snubbers), that will be used for shipboard installations. If an item is to be mounted both directly to foundation structures or on resilient mountings onboard ship, or both, the item may be tested for direct mounting (upon concurrence from NAVSEA) without additional testing for resilient mounting. Mountings used in shock testing shall not be used aboard ship.
Government-furnished equipment shall not be subjected to shock testing after delivery to the contractor. Unless otherwise specified, when contractor-furnished consoles, racks, and enclosures containing Government-furnished equipment are shock tested, the Government-furnished equipment shall be simulated by equivalent dummy loads.
Where Government or other applicable equipment specifications require shock proofing for other than non-contact underwater explosions, the requirements of such other specifications shall also apply.
Valves and valve operators in shock Grade A or B piping systems shall be tested and inspected for qualification in accordance with MIL-STD-798, Section 11.
Sea water system hull valves which have been subjected to shock tests shall not be installed in the ship as hull valves, but may, after proper examination and testing, be used as line valves when found to satisfy the requirements of MIL-STD-798, Section 11.
Castings which have been subjected to actual shock testing shall not be installed in the ship between the sea and the associated hull valves.
Following shock tests, valves shall be disassembled and inspected for evidence of mechanical binding, or distortion of components, and shall be inspected for soundness before and after shock testing, through the use of magnetic particle or dye penetrant tests complying with MIL-STD-271.
Items which are qualified for a higher grade of shock resistance may be used where a lower grade is specified.
Equipment shall not be attached to both of two structures which can deflect relative to each other under shock loadings.
Buffers employed to limit deflection under shock loading are subject to the same requirements as foundations.
Unless otherwise specified herein or in Government specifications, government-furnished equipment will be suitable for mounting directly to foundation structures.
Section 072 2
Unless specified otherwise in these specifications, bolts for shock grade A and B equipment shall be installed in holes no greater than the following sizes:
Nominal bolt diameter (inches) Maximum diameter of hole (inches) 3/4 and smaller Nominal bolt dia. plus 1/32 inch Larger than 3/4 Nominal bolt dia. plus 1/16 inch For mounting hole size of DIM mounted equipment see Section 073.
Where grade A or B machinery or equipment is removed for overhaul or repair, replacement hardware for reinstallation of equipment (bolts, fittings, hangers, etc.) shall be in accordance with original installation drawings so that original shock resistance shall be preserved.
The following shock requirement paragraphs of this section are cross-referenced to its associated technical requirements by the applicable specifications section number. For example, paragraph 072-180 herein contains the shock requirements for associated technical requirements contained in Section 180.
072e. Hull Structure Shock Requirements 072-100. Hull Structure
Hull structure designed for normal ship dynamic loads is generally adequate for shock loading. For shock design purposes, foundations shall generally be considered to end at the point where normal ship structure begins. Care shall be taken to avoid any sudden structural discontinuity between foundations and ship structure. Pads, chocks, brackets, or local stiffening of ship structure shall be used to provide structural continuity where necessary.
For non alignment-sensitive installations, local headers, pads, chocks, or brackets added to stiffen plating or framing in way of equipment, or to provide attachment points for foundations, need not be designed to withstand shock loadings. For alignment-sensitive installations, all structure expressly added for support of the equipment (including additional headers, pads, and normal ship structural members whose size has been locally increased specifically to suit the installation) shall be designed to withstand foundation reactions under shock loadings. Insofar as practical and compatible with other requirements, supporting ship structure for alignment-sensitive installations shall be balanced from the standpoint of resistance to deflection in the vertical direction to minimize tilting (angular misalignment) due to vertical shock.
Stanchions provided primarily to support heavy equipment shall be treated as an extension of the foundation and designed to withstand shock loadings.
Machinery space upper levels which are provided solely as a support for auxiliary machinery shall be considered as foundations grounded on frames or inner bottom and shall be designed to withstand shock loadings.
072-164. Ballistic plating
Parasitic protective plates and their connections to ship structure shall meet grade A shock requirements.
072-170. Masts and spars
Foundations and support structure for essential equipment mounted on masts and spars shall meet grade A shock requirements.
072-180. Foundations
Strength and rigidity of foundations shall be suitable to withstand shock loads (where required) and to distribute them into the structure of the hull.
All foundations which support grade A or B equipment shall be assigned the same shock grade as the supported equipment.
If practicable, foundation structure for grade A and grade B equipment shall be shock tested with the equipment it supports. If this is impracticable, the foundation shall be designed to the dynamic shock analysis procedure indicated in Section 072d.
In general, possible shock damage shall be minimized. If misalignment would not interfere with operation of equipment, permanent deformation of the foundation is preferable to damage to the equipment or the hull. In any case, deformation should take the form of buckling or bending of local structure, rather than permitting the equipment to tear loose from its attachment. Foundation structure shall be proportioned to give a reasonable and uniform stress distribution, permitting maximum absorption of energy through elastic deformation.
Re-entrant corners and other causes of stress concentrations shall be avoided. Brittle materials, such as cast iron, shall not be used. Under vertical shock forces, belts shall be stressed in tension rather than shear, insofar as practicable. For permissible bolt hole clearances, see Section 072d.
072f. Propulsion Plant Shock Requirements 072-200. Propulsion plant
Unless otherwise specified, all systems and components of the propulsion plant, including propeller and shafting systems as well as all other independent auxiliaries necessary for the safety and continued combat capability of the ship shall meet grade A shock requirements.
072-231. Propulsion steam turbines
Turbines and accessories shall meet grade A shock requirements.
072-235. Electric propulsion systems
Electric propulsion systems and their components shall meet grade A shock requirements.
072-243. Propulsion shafting
The shafting system and its components shall meet grade A shock requirements. The dynamic design analysis method specified herein shall be used. The shafting system shall not be shock tested. For purposes of dynamic design analysis, the shafting system shall include the shafting, bearings, seals, stuffing boxes, propeller, and associated units.
072-245. Propellers
The propeller and all its components shall meet the requirements of grade A shock. However, the propeller shall not be shock tested or dynamically analyzed but shall be considered as a mass in the analysis of the shafting system.
072-251. Forced draft systems
The forced draft blowers and combustion air systems and associated components of these systems shall meet grade A shock requirements. The associated components shall include main steam inlet valve, nozzle valves, shutters, and speed controls.
072-253. Steam systems
Where applicable, the steam systems and all components shall meet the following grades of shock resistance:
Grade A:
Reduced pressure steam systems except those listed below as Grade B or C Grade B or C:
Equipment and components of the condensate and feedwater system shall meet the grade of shock resistance as follows:
Grade A:
Morpholine condensate treatment system Reserve feed fill and transfer
072-256. Machinery seawater circulating water and cooling water systems
All equipment and components of the machinery circulating water and cooling water systems of combatant ships and selected auxiliary type ships shall meet the grade of shock resistance as follows:
Grade A:
Air conditioning refrigeration seawater cooling system Air deballasting compressor cooling system
Auxiliary machinery seawater cooling system Internal combustion engine seawater cooling system Propulsion seawater circulating systems
Turbo-generator condenser seawater circulating system
Section 072 4
Grade B:
Jet engine test facility seawater cooling system Ships Service refrigeration seawater cooling system
072-259. Internal combustion engine, combustion air, and exhaust systems The induction air and exhaust systems shall meet grade A shock requirements.
072-262. Lubricating systems
All equipment and components of the lubricating oil systems shall meet the grade of shock resistance as follows:
Grade A:
Lubricating oil service systems for main propulsion units and turbine/diesel driven generators Lubricating oil service systems or portions thereof furnished with machinery units
Grade B or C:
Lubricating oil filling, transfer, and purifying systems Aviation lubricating oil system
Contaminated aviation lubricating oil systems 072g. Electric Plant Shock Requirements
072-300. Electric plant
Components of the electric plant shall meet the following grades of shock resistance:
Grade A:
Equipment, auxiliaries, and controls, serving or supporting equipment required to meet grade A shock requirements Equipment required to meet grade A shock requirements by their individual specifications
Navigational equipment and facilities Replenishment-at-sea equipment and facilities
Ship service and emergency generators, their auxiliaries and controls Ship service and emergency lighting fixtures
Ship service, emergency, casualty power, and lighting distribution systems. This shall include all equipment, auxiliaries, and controls of these systems from the electric power source to the terminals of the load to be served.
Weapons control equipment and facilities
Grade B:
Battery charging panels Detail lighting fixtures
Electric furnaces
Equipment required to meet grade B shock requirements by their individual specifications
Shore terminal boxes
Test panels and test switchboards
Welding motor-generators
Grade C:
Electrical equipment not covered by grade A or grade B classification 072h. Command and Surveillance Shock Requirements
072-400. Electronic systems
Government-furnished electronics equipment shall not be subjected to shock testing by the contractor. When contractor-furnished electronics consoles, racks, enclosures, or foundations are shock tested, the contractor shall simulate the Government-furnished electronics equipment by the use of equivalent dummy loads, unless otherwise specified.
Electronic equipment shall be installed on resilient mounts only if required by the Government. Equipment-to-equipment and equipment-to-bulkhead clearance shall be provided for the effects of mount excursion. If resilient mounts require replacement they shall be replaced with the same type and size as those provided as part of the equipment. Cabling and transmission line installations shall not impair mount excursion.
The shock grade requirements, defined herein, shall apply to all components, including transmission lines, remote facilities, and mounting facilities. Equipment and facilities shall be graded as follows:
Grade A:
Command decision and display installations Countermeasures facilities
Electronic navigation facilities
IFF facilities
Infrared beacon facilities
Infrared communications facilities Meteorological facilities
Radar facilities
Radio communication facilities (except AN/SRC-34 transceiver)
Sonar facilities
Grade B:
Bathythermograph facilities (except probes)
TACAN facilities
Unless otherwise specified, all systems designated vital or semi-vital, ship control console, and interior communication switchboards shall meet grade A shock requirements. Other systems including voice tubes, pneumatic tubes, passing scuttles, and passing tubes shall meet grade B shock requirements.
072-443. Whistles
Whistles and fog timers shall meet grade B shock requirements.
072-475. Degaussing systems
The degaussing system and all components shall meet grade A shock requirements.
072-476. Mine countermeasure systems
Electrical control equipment for use in mine countermeasures shall meet grade A shock requirements unless mounted in a shock-mitigated area. Mine hunting and mine neutralization equipment and stowage chocks, racks, and cradles for all countermeasures equipment shall meet grade A shock requirements.
072-480. Fire control systems
All fire control equipment and systems shall meet grade A shock requirements.
072-494. Meteorological requirements
Meteorological equipment and systems shall meet grade A shock requirements, except for remote environmental sensor and sensor readout equipment which shall meet grade B shock requirements.
072i. Auxiliary Systems Shock Requirements 072-502. Auxiliary machinery
All auxiliary machinery and associated system shall meet grade A shock requirements.
072-503. Pumps
The shock grade requirements for all pumps shall be as specified for the system of which the pump is a component.
072-505. General requirements for piping systems
Piping systems shall have sufficient flexibility to prevent overstressing of piping materials or supports, leakage of joints, and unacceptable distortion of connected equipment due to shock loadings (where applicable).
Supports shall be installed on or adjacent to concentrated weights in the piping system to preclude contact with adjacent pipe, equipment, and structure under shock loading.
Where resilient mounts are used for supports, the supports shall be at least two in a "V" configuration with suspension such that each mount will be loaded along its axis and will provide maximum pipe support and shock attenuation under vertical and athwartship shock.
Mechanical components shall meet the grade of shock as specified herein for the individual system of which they are components.
Pipe flanges and standard fittings are not required to be high impact shock tested.
Positions and pressure conditions under which valves shall be mechanically shock tested shall be in accordance with MIL-STD-798.
072-506. Overflows, air escapes, and sounding arrangements
Overflows, air escapes, and sounding tubes shall meet grade A shock requirements if they support grade A shock equipment or are required for damage or casualty control. Otherwise they shall meet grade B or C shock requirements.
072-512. Heating, ventilation, and air conditioning (HVAC)
The HVAC systems that are classified "W" or circle W and all components of these systems (except those components noted herein) shall meet grade A shock requirements.
Section 072 6
Humidistats and humidifiers which do not meet grade A shock requirements, shall be mounted to meet grade B or C shock requirements.
The HVAC systems that are classified "X", "Y", or "Z" and all components of these systems shall meet grade B or C shock requirements, except those systems, portions of systems, and components which are related to the preservation of stability of watertightness shall meet grade A shock requirements (example - watertight bulkhead valves).
072-516. Refrigeration plants
Air conditioning, cargo, and ships stores refrigerant machinery and associated systems thereof shall meet grade A shock requirements.
Self-contained and unitary equipment and associated systems thereof shall meet grade B or C shock requirements.
072-521. Seawater service systems
All seawater service systems and components shall meet the requirements of grade A shock, except for those portions of the flushing system which are secured during condition ZEBRA. These portions shall be arranged and located to meet grade C requirements, or where required, grade B requirements.
072-531. Distilling plants
Distilling systems shall meet grade A shock requirements.
072-532. Fresh Water Service System
The Air Conditioning Chilled Water System, Electronics Water Cooling System, Internal Combustion Engine (Diesel) Jacket Water Cooling System, and all components of these systems shall meet the requirements of Grade A Shock.
All components of the Potable Water System involved in supply to IOIC Equipment, Machinery Spaces, Decontamination Stations, Medical Treatment Facilities, Photographic Spaces and Vital Electronic Space Fire Fighting System shall meet Grade A Shock.
The remaining portions of the Potable Water System in addition to Catapult Water Brake Cooling System shall meet Grade B Shock requirements.
072-534. Machinery and piping systems drainage
All equipment and components of the machinery and piping systems drainage systems for combatant type ships and selected auxiliary type ships shall meet the following grades of shock resistance:
Grade A:
Heat exchanger vents and drains (downstream of cutout valve) Oily water drain system
Equipment and components of fuel systems shall meet the grade of shock resistance as follows:
Grade A:
Cargo oil fill and transfer systems
Emergency generator fuel transfer and service systems Fuel fill, transfer, stripping, and service systems
Grade B:
Tank liquid level indicating systems
Grade C:
Cargo oil tank cleaning and gas freeing systems 072-551. Compressed air systems
Equipment and components of compressed air systems shall meet grade A shock requirements.
072-552. Compressed gas systems
The nitrogen systems and all components of these systems shall meet grade A shock requirements.
072-555. Fire extinguishing systems
All fire extinguishing systems and components shall meet grade A shock requirements.
072-558. Special piping systems
Systems containing flammable or hazardous fluids shall meet grade A shock requirements except for the dry cleaning plant and photographic processing equipment which meets grade C shock requirements.
072-561. Steering gear
All components of the steering gear system shall meet grade A shock requirements.
072-562. Rudders
The rudders, rudder stocks, bearings, and support assemblies shall be designed to meet grade A shock requirements.
072-571. Replenishment-at-sea systems
Equipment and components of replenishment-at-sea systems shall meet grade A shock requirements in the stowed position.
072-572. Stores handling systems
Stores handling equipment shall meet grade B shock requirements in the stowed position.
072-573. Cargo handling systems
Cargo handling equipment including cranes, booms, elevators and conveyors shall meet grade B shock requirements.
Cargo handling equipment including cranes, booms, elevators and conveyors shall meet grade B shock requirements.