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11.2.1.6.8. Filter design shall permit easy servicing and ready accessibility.
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11.2.1.7. Generic Ground Support Pressure System Identification and Marking. All hazardous pressure system components shall be identified as to function, content, applicable hazard, and, if applicable, direction of flow. The marking and identification shall be accomplished by some means that cannot cause “stress concentration” or otherwise reduce the integrity of the system. Minimum identification and marking requirements are as follows:
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11.2.1.7.2. Portable and mobile pressure vessels shall be marked in accordance with the applicable DOT specifications.
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11.2.1.7.3. Individual lengths or fabricated assemblies of pipe and tubing shall be identified with part number and/or contractor tracking number, pipe or tube size, schedule number or wall thickness, test pressure, and the date of hydrostatic and/or pneumatic test. Identification data shall be affixed to fabricated assemblies by means of an attached stainless steel band or “dog tag” that has been stamped or electrochemically etched. When the tag does not contain the above identification data, data shall be made available for review on site.
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11.2.1.7.6. Shutoff and metering valves, pressure relief valves, regulators, gauges, check valves, quick disconnect ground half couplings, and filters shall have the manufacturer part number, unique serial number, and system reference designation for the component (i.e., CV1, CV2), permanently attached to the body by stamping, engraving, or tagging when acceptable to the PSWG and Range Safety. The following information shall be provided in the SDP (MSPSP):
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11.2.1.7.6.1. Manufacturer and/or contractor name.
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11.2.1.7.6.2. Manufacturer part number.
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11.2.1.7.6.3. Applicable design pressure rating.
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11.2.1.7.6.4. Service media.
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11.2.1.7.6.5. Month and year of most recent calibration for gauges and transducers.
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11.2.1.7.6.6. Flow direction arrow, if applicable.
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11.2.1.7.6.7. System reference designation for the component, such as CV1, CV2.
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11.2.1.7.6.8. Unique serial number.
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11.2.1.7.7. All manual pressure system regulation and control panels and consoles shall be clearly marked with a flow schematic, operating parameters, and component identification.
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11.2.1.7.8. The system shall be designed or marked to prevent incorrect installation of filters.
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11.2.1.7.9. Flexible hoses shall be provided with an identification tag that is permanently and legibly marked with the manufacturer part number, unique serial number, and system reference designation for the hose (i.e., FH1, FH2), and the following shall be provided in the SDP (MSPSP):
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11.2.1.7.9.1. Manufacturer name.
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11.2.1.7.9.2. Manufacturer and/or contractor part number.
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11.2.1.7.9.3. Hose size, date of manufacture, and effective shelf/use life.
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11.2.1.7.9.4. Maximum allowable working pressure (MAWP) or manufacturer rated working pressure.
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11.2.1.7.9.5. Service media.
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11.2.1.7.9.6. Month and year of most recent hydrostatic test and test pressure.
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11.2.1.7.9.7. System reference designation for the hose, such as FH1, FH2.
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11.2.1.7.9.8. Unique serial number.
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11.2.1.7.10. An identification tag that is permanently and legibly marked with the month and year of the most recent set pressure calibration shall be attached to the relief valve.
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11.2.1.8. Generic Ground Support Pressure System Bonding and Grounding.
Electrical bonds are classified according to the purpose for the bond: Class C for power return, Class H for shock hazard, Class R for radio frequency, Class L for lightning, and Class S for electrostatic charge. There may be more than one purpose for bonding a specific interface, and the bond shall meet the requirements of each applicable class maintaining all conductive external parts and surfaces at ground potential at all times and in all anticipated conditions. At a minimum electrostatic charge build-up must be addressed. NASA-STD 4003, Electrical Bonding for NASA Launch Vehicles, Spacecraft, Payloads, and Flight Equipment, and NFPA 77, Recommended Practices on Static Electricity, shall be used for guidance.
All pressure systems shall be designed to ensure that all piping, tubing, external parts, shields, and surfaces are at ground potential at all times. To control and dissipate the build-up of electrostatic charges, all pressure systems shall be properly bonded, grounded, and constructed to provide the following:
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11.2.1.8.1. Any single joint measurement shall exhibit a DC resistance of 1.0 ohm or less.
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11.2.1.8.2. DC resistance from any point in the piping and tubing system to the nearest earth electrode ground plate shall be 1.0 ohm or less.
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11.2.1.8.3. A low-impedance path to earth shall be provided for electrical currents resulting from lightning discharges or electrical power system faults to minimize abnormal voltage rises that might injure personnel or damage equipment.
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11.2.1.8.4. A discharge path shall be provided between distribution piping and tubing and earth to prevent the buildup of static electricity.
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11.2.1.8.7. Flanged joints are acceptable if the flanges are stainless steel or the flanged areas in contact with the bolt heads and washers are clean and bright. In addition, the bolts and nuts shall be equipped with serrated or spring washers to maintain tightness.
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11.2.1.8.8. Tubing sections joined with fittings that seat metal-to-metal are considered adequately bonded.
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11.2.1.8.9. All mobile equipment shall be equipped for connection to bonding and grounding stations.
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11.2.1.8.10. Grounds shall be provided for propellant loading systems (flight propulsion systems or ground propellant tanks) to allow for common grounding and bonding during propellant transfer operations. Loading systems include portable vessels and units.
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11.2.1.8.11. The use of interconnecting dissimilar ground metals that could lead to increased resistance due to galvanic corrosion over a relatively short time period shall be avoided.
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11.2.1.8.12. Nonmetallic plumbing installations shall be designed so that the static voltage, generated by fluid flow, will not exceed 350 volts at any point outside the pipes, tubes, or hoses.
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11.2.1.8.13. The resistance of nonmetallic hoses shall not exceed 1.0 megohm per meter of length so as to dissipate charges developing within the fluid or between fluid and the hose.
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11.2.1.9. Generic Ground Support Pressure System Physical Arrangement and Human Factors. Pressure systems shall be designed to provide adequate accessibility, clearance, and operating safety.
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MIL-STD-1472 or the equivalent should be used as guidance in designing pressure system operating consoles.
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11.2.1.9.1. Hypergolic propellant system design shall take into consideration the limitations imposed on individuals dressed in Self-Contained Atmospheric Protective Ensemble (SCAPE) suits or Propellant Handlers Ensemble (PHE).
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11.2.1.9.2. All components and piping shall be located so they are readily accessible for maintenance, inspection, and calibration. All piping shall be located to preclude a hazard to personnel (tripping or head injury).
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11.2.1.9.3. Tubing shall be located and protected so that damage cannot occur due to being stepped on, used as handholds, or by manipulation of tools during maintenance.
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11.2.1.9.4. Pressure lines shall clear all structures, components, and other lines by not less than 1/4 inch under the most adverse conditions of service to ensure that abrasive chafing does not occur.
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11.2.1.9.5. Piping, tubing, and other components shall be routed or located to provide protection from other operational hazards, including moveable equipment. Where such exposure is unavoidable, safeguards that minimize the effects of such exposure shall be incorporated in the design.
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11.2.1.9.6. Maximum spacing shall be provided between oxidizer and fuel lines to preclude mixing and combustion. A minimum of 24 inches shall be provided.
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11.2.1.9.7. Pipes containing liquids shall not be attached or secured to electrical lines or conduit.
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11.2.1.9.8. A two-inch space shall be maintained between electrical conduits and pressure lines.
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11.2.1.9.9. Vent outlets shall be located far enough away from incompatible propellant systems and incompatible materials to ensure that no contact is made during vent operations.
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11.2.1.9.10. System connections for incompatible propellants shall be keyed, sized, or located so that it is physically impossible to interconnect them.
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11.2.1.9.11. Safety relief valves and burst diaphragms shall be located so that their discharge is directed away from personnel and any safety critical equipment to prevent injury to personnel or damage to safety critical equipment. If this requirement cannot be met, safety valves and burst diaphragms shall be equipped with deflection devices. Consideration shall be given to minimizing the noise hazard of high pressure venting.
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11.2.1.9.12. Vent lines for flammable and combustible vapors, toxic gases, and gas streams that may be contaminated with toxic vapors shall be extended away from work areas to prevent accidental ignition of vapors and/or injury to personnel.
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11.2.1.9.13. Pipe or flex hose routing shall not block personnel egress routes.
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11.2.1.9.14. Pressure systems shall be designed so that the operator is not required to leave the operating control station to monitor the hazard level of that system.
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11.2.1.9.15. Valves carrying hazardous liquids shall not be located overhead in the area of an operating station.
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11.2.1.9.16. Manually operated liquid valves shall be located to permit operation from the side or above to prevent spillage of service fluid on the operator due to leak or failure of the valve seals.
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11.2.1.9.17. For systems with failure modes that could result in a time-critical emergency, provision shall be made for automatic switching to a safe mode of operation. Caution and warning signals shall be provided for these time-critical functions.
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11.2.1.9.18. Pressure systems shall be designed so that removal and replacement of tubing can be accomplished with minimal removal of other system components.
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11.2.1.9.19. Systems shall be designed with accessibility to perform end-to-end static ground system checks.
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