MN471000, Pressure Safety Manual
Sponsor: Michael W. Hazen, 4000 |
Revision Date: October 7, 2007
Replaces Document Dated: August 29, 2007 |
This document is no longer a CPR. This document implements the requirements of Corporate procedure ESH100.2.PS.1, Control Pressure Safety Hazards.
IMPORTANT NOTICE: A printed copy of this document may not be the document currently in effect. The official version is the online version located on the Sandia Restricted Network (SRN).
Pressure Safety Manual
10. VACUUM SAFETY
Subject Matter Experts: Shane Page, and David Paoletta
Contributor: Pressure Safety Committee
MN471000, Issue R (Q not used)
Revision Date: October 8, 2007; Replaces Document Dated: August 29, 2007
Administrative Changes: November 21, 2007, January 28, 2008, December 17, 2009, June 8, 2010, and May 26, 2011, and January 19, 2012
Guidance
The term "vacuum" refers to a space that has gas pressure below ambient atmospheric pressure. These systems may present some hazards and employ components that are unique and separate from pressure systems where the gas-pressure is greater than ambient atmospheric pressure. A vacuum system includes all of the components, e.g., the main vacuum vessel, plumbing, and pumps.
Guidance
Vacuum systems contain less than ambient atmospheric pressure, also referred to as "negative internal pressure." Measurements of the remaining gases in vacuum systems are referred to as pressure measurements (operating pressure or system ultimate pressure), and are typically in absolute units, such as microns, torr, millibar, or pascals.
Note: The ASME Boiler and Pressure Vessel Code, Sec. VIII, Div. 1, Part UG-28 refers to these systems as being under "external pressure."
Guidance
Systems containing pressures greater than ambient atmospheric are differentiated from negative internal pressure systems by referring to them as "positive internal pressure" systems. Pressure measurements for positive internal pressure systems are often not in absolute units but are commonly in gauge pressure units (typically, pounds per square inch gauge [psig]).
Guidance
"Vacuum-only" systems are systems in which all intended processes or experiments are conducted at pressures less than ambient atmospheric pressure. These systems are brought up to atmospheric pressure for backfill and venting operations. Minimal positive (greater than ambient atmospheric) internal pressures may be allowed for purge purposes when opening a system to the atmosphere.
In general, vacuum-only systems are designed for negative internal pressure and contain components and design concepts that make a positive internal overpressure test inappropriate. Therefore, other means may be used to determine the safety of these systems.
Vacuum-only systems must be protected from accidental overpressurization by applicable protective devices or techniques discussed in this appendix.
Requirements
System owners shall address the possible effects of any positive-pressure sources, such as process or backfill gases, connected to the system when considering the vacuum system's safety and approach to overpressure protection.
Requirements
System owners shall be aware that vacuum systems that are also used at positive internal pressures are subject to the requirements of the Pressure Safety Manual.
Guidance
Vacuum systems, like all pressure systems, are required to be safe when used in occupied areas. A thorough approach to the pressure safety aspects of vacuum systems involves evaluating systems to ensure that they meet the following requirements:
- Design and fabrication employing industry standard practices that provide an adequate safety factor with respect to the mode of intended use and the predicted failure mode.
- Proper materials and processes of construction.
- Appropriately rated components for the given application.
- Identification of all pressure sources associated with the vacuum system.
- Adequate overpressure protection from pressure sources associated with the system.
- Shielding or isolation of certain nonrated or brittle material components or the use of personal protective equipment in the vicinity of these components.
- Documentation of the system safety.
Guidance
The following is a vacuum system design guidance flowchart that presents the suggested steps for evaluation of a vacuum system.
Guidance
The terms "approved" and "reputable" indicate suppliers who have a proven history of acceptable quality products and who adhere to industry standard design parameters with respect to the following:
- Materials of construction
- Wall thicknesses
- Adequate safety factors
- Fabrication techniques
Experience shows that vacuum systems (or components) fabricated by reputable manufacturers adhere to acceptable safety standards. The acceptance and documentation of these systems is therefore simpler than that of systems or components not fabricated by reputable manufacturers.
Guidance
A vacuum system meets the safety requirements of this manual if that system is purchased from an "approved" supplier, which includes systems assembled from commercially available components from approved suppliers. The following are factors for approving a supplier:
- Industry experience in the acceptable design and fabrication of similar systems
- The time as a "reputable" supplier (preference is given for five or more years). Suppliers with less than five years experience may be approved if they can show experience in the acceptable design and fabrication of similar systems.
Requirements
The system owner shall approve the supplier, with the agreement of the SNL organization manager, pressure advisor or vacuum consultant, and any applicable SNL purchasing agent.
Note: An SNL pressure advisor shall sign all purchase requisitions for vacuum systems and components in the special approval block of the Purchase Requisition Form as required by Supply Chain Management requirements.
Guidance
Vacuum system personnel should see the Pressure Safety homepage for a listing of reputable vacuum equipment manufacturers who may be approved for fabrication of a vacuum system. This list is not intended to be all inclusive; other suppliers may be approved by the SNL organization involved with the acceptance of the system.
Guidance
Vacuum system personnel should use a step-by-step approach when specifying, designing, fabricating, or purchasing a vacuum system such as the following:
- Select a design concept.
- Specify and define the system requirements and operating conditions.
- Select or specify the materials and processes.
- Specify any leak rate testing or other certifications that may be required for acceptance of the system.
Guidance
Vacuum system personnel should consider the following when selecting a design concept:
- Use vacuum industry standard design parameters for systems fabricated by reputable suppliers.
- Show an adequate safety factor with consideration to a safe failure mode for systems not fabricated by reputable manufacturers. Use ASME Boiler and Pressure Vessel Code, Sec. VIII, Div. 1, Part UG-28 as a minimum standard for vacuum systems. This does not imply that vacuum systems require an ASME Code stamp; the ASME Code stamp is not available from many of the industry leading vacuum system manufacturers.
Note: Vacuum industry standard designs are generally based on structural stiffness and minimization of deflection as incorporated in ASME Boiler and Pressure Vessel Code, Sec. VIII, Div. 1, Part UG-28 for shells and tubes under external pressure. Conversely, ASME requirements for positive internal pressure design are based on yield parameters.
Note: Welding techniques for vacuum systems may differ from those of positive-pressure systems. Skip welding (for example, on the outside of flanges) allows for leak testing and minimizes virtual leaks.
Guidance
Vacuum system personnel should consider the following when specifying and defining the system requirements and operating conditions:
- Include a complete description of the size and geometry of the system.
- List specific requirements (e.g., on pumping ports, access ports, instrumentation requirements, and types of flanges to be used).
- Specify ultimate system pressure and the expected operating pressure regime of the system.
- Identify the system gas load (e.g., list the gas species and estimate the process gas load, leakage, and outgassing) and specify the pumping speed(s) and types of pump(s) expected to be used to evacuate the system.
- Specify the time allowed to achieve the ultimate system pressure and any applicable bakeout times and temperatures required to achieve this ultimate pressure.
Guidance
Vacuum system personnel should consider the following when selecting or specifying materials and processes:
- Consult with materials experts about the proper selection of the vacuum system's materials of construction. Generally, the materials should exhibit a ductile failure mode throughout the range of operating temperatures.
- If applicable, specify the system's requirements for ultimate pressure, temperature ranges, permeation and desorption characteristics, and compatibility with system process gases that may adversely affect the material's properties.
- If applicable, specify production processes for the materials of construction. For example, vacuum melted stainless steel may be an appropriate specification for systems expected to be operated in the ultra high-vacuum (UHV) range.
- Specify vacuum industry standard weld designs that minimize leakage (actual or virtual).
- If applicable, specify other parameters, such as surface finish or cleaning/bakeout procedures, for certain vacuum applications.
- Compile applicable documentation of the above design parameters, including any applicable engineering drawings or calculations, for the system data package.
Requirements
Vacuum system personnel shall:
- Request additional information from suppliers not listed as approved and reputable or compile the additional information to ensure that the vendor can meet the safety requirements of this appendix.
- Perform a thorough design review before suppliers begin fabrication when dealing with suppliers without a proven history.
Requirements
Vacuum system personnel shall accept that a vacuum system not fabricated by an approved supplier meets the appropriate design and processing criteria if information from the supplier that describes materials of construction, welding, and system design parameters has been obtained and the system meets one of the following:
- The system has been qualified with an overpressure test, typically at 1.5 atm (18 to 22 psig, depending on altitude) to confirm the structural integrity of the vessel or component. Determine the specifics of the overpressure test as appropriate for each case.
Note: ASME code calls for internal overpressure tests. However, most vacuum systems contain components designed for external pressure only, which makes an internal overpressure test inappropriate. External overpressure tests also may not be appropriate for some vacuum vessels.
- The system has been qualified by a safety analysis.
Requirements
Vacuum system personnel shall ensure that a safety analysis for a vacuum system from a supplier who is not listed as approved and reputable satisfies both of the following:
- An adequate factor of safety based on the appropriate failure mechanism, which shows the design safety margins for the vessel or component to indicate why the system is safe. The vessel or component should satisfy the requirements of the ASME Boiler and Pressure Vessel Code, Sec. VIII, Div. 1, Part UG-28 for shells and tubes under external pressure, or show that the design is equivalent to those requirements.
- Proper materials and processes, including joining processes (for example, welding and brazing) were used in construction of the system.
Note: An external overpressure test is not required.
Requirements
Vacuum system personnel shall:
- Ensure that additional analysis is performed for systems that do not satisfy the requirements of the ASME Boiler and Pressure Vessel Code, Sec. VIII, Div. 1, Part UG-28 or the equivalent. The additional analysis must assess the design safety factor based on the applicable failure mode and show consideration for the consequences of failure and any applicable mitigation techniques to show that the system is safe.
- Ensure that the metal used for vacuum systems must exhibit a ductile failure mode throughout the temperature range of operation; in general, annealed 300 series stainless steels, 6000 series aluminum, and copper/brass alloys meet this requirement.
Requirements
Vacuum system personnel shall consult materials and metallurgy experts to ensure that those materials have sufficient ductility for the application, if system operation calls for harsh environments (e.g., containment of corrosives).
Guidance
When specifying and verifying welds and brazes, vacuum system personnel should consider the following guidelines:
- Specify and verify proper welds and brazes for the joint design and material of construction.
- Determine and perform appropriate tests for each case and detail them in the system documentation.
- Determine and document the consequences of failure.
Note: ASME code calls for internal overpressure tests. However, most vacuum systems contain components designed for external pressure only, which makes an internal overpressure test inappropriate. External overpressure tests also may not be appropriate for some vacuum vessels.
Requirements
Vacuum system personnel shall provide overpressurization protection for vacuum systems which have identified pressure sources with a safety manifold as shown in Chapter 5 of this manual or shall otherwise adequately protect them by an alternate technique from overpressurization.
Guidance
Vacuum systems meet the SNL definition of pressure systems; however, there are basic differences between vacuum systems and positive (greater than ambient atmospheric) internal pressure systems that should be recognized and appreciated to adequately address safety concerns and maintain vacuum system integrity.
Briefly stated, all plausible pressure sources of vacuum systems should be identified and adequate overpressure protection should be provided to protect the vacuum system and components from these pressure sources. Overpressure protection can be implemented using a variety of techniques.
Evaluation of all plausible pressure sources in any given system is necessary to adequately address overpressure protection.
Vacuum system personnel should be cognizant of the following vacuum system pressure sources and overpressure protection techniques.
Guidance
Some common pressure sources associated with vacuum systems include process and backfill gases.
Process gases are typically gases supplied from high-pressure gas cylinders. Backfill gases are also supplied from gas cylinders or may be supplied from "house" sources, such as nitrogen gas from a liquid nitrogen tank.
Guidance
Additional types of pressure sources that are not as commonly recognized include the following:
Guidance
Increasing temperature may affect system pressure in vacuum systems capable of operation above room temperature. Typically, systems are heated while under vacuum for degassing or process purposes. However, if a closed system is inadvertently backfilled and then heated, pressure could rise significantly. A vacuum system, closed and vented to 1 atm at room temperature, will see a pressure rise of nearly 20 psig when heated to 400°C. This obviously could present a significant hazard that should be mitigated through the use of a pressure relief device or other controls or interlocks.
Guidance
It is common for vacuum-only systems to be connected to positive pressure gas sources in order to admit process or backfill or purge gases into the system. These gas sources typically include the following:
- DOT cylinders
- Regulators
- Control hardware (for example, metering valves and mass flow controllers)
- Piping
The vacuum system's safety and approach to overpressure protection should identify these positive pressure gas sources and their possible effects on the vacuum system.
Guidance
Other system-specific pressure sources may exist (e.g., the mixing of reactive gases or other chemical reactions and the subsequent generation of high pressures).
Guidance
The following are means for providing overpressure protection for vacuum systems:
- Pressure relief devices
- Gravity/vacuum closure devices
- Procedural controls
Requirements
Vacuum system personnel shall ensure that relief devices located directly on the vacuum chamber do not limit the vacuum integrity of the system. When relief devices are located on the associated gas supply lines, use relief devices on all pressure lines into the chamber and ensure that no unforeseen pressure sources exist in the chamber (such as the warming of cryogenic components).
Guidance
Vacuum system personnel should be cognizant of the following guidelines concerning vacuum application pressure relief devices.
Guidance
Pressure relief devices specially intended for vacuum system applications that have the necessary low set pressure and high flow capacity and that provide reliable service (low leakage rates) are made by vacuum or cryogenic equipment manufacturers. They are available through the JIT or other vacuum component suppliers in the form of pressure relief valves and burst disks. The selection of a particular pressure relief device and its location on the system is dependent upon the specific system construction, system hazards, and vacuum requirements.
Hardware suitable for even the most stringent demands of ultra high-vacuum systems is commercially available, with typical ranges from 2 to 5 psig for pressure relief valves and 3 to 5 psig for burst disks.
Guidance
There are three main characteristics of relief devices for vacuum applications:
- Low set pressure
- High flow capacity
- High quality(minimal leakage)
Guidance
Determine the correct placement of the pressure relief device according to the guidance in Chapter 5 of this manual. Generally, the relief device should be located on the vacuum system itself or on the pressure source line as it leads to the vacuum system. When located on the pressure source line, the device should relieve at a pressure low enough to protect the vacuum system.
Guidance
Because a maximum allowable working pressure (MAWP) is generally not specified for a vacuum only system or component, use the "as low as reasonably achievable" (ALARA) principle to determine the set pressure of the pressure relief device.
Evaluate the following to determine the set pressure:
- The type of pressure relief device chosen
- Location of the pressure relief device, either on the vacuum system itself or on the associated pressure source piping
- Reliable system operation
- Operational characteristics of the associated pressure source
- Any other system-specific hazards or concerns
Guidance
Vacuum systems present special sizing problems (relief device flow capacity), and devices may be necessary to reduce the pressure source flow rate to a level compatible with the relief device capacity. Refer to Chapter 5 of the Pressure Safety Manual under "Protective Pressure Relieving Devices" for a discussion of special sizing problems.
Calculations should show a minimal and acceptable amount of accumulated pressure across the relief device during the worst-case overpressure scenario.
Guidance
Flow-restrictive components in the pressure supply line can be used to limit the flow capacity requirements for the pressure relief valve.
Excess flow valves should also be used to address the issue of flow capacity. In these cases, the relief device must have sufficient capacity to actuate the excess flow valve and thereby isolate the pressure source.
Excess flow valves used for this purpose should not be left in the locked or manually open position.
Guidance
The leak integrity of the relief device should be commensurate with the vacuum system requirements.
When selecting a pressure relief device, the leak integrity of both the mounting connection and valve closure seal should be evaluated.
Guidance
Seek advice from your pressure advisor, local vacuum consultant, or the
Safety Engineering Department (4122) (Health & Safety Department [8517] at SNL/CA) on the selection and location of pressure relief devices for vacuum systems.
Vacuum component sales representatives can also supply information on pressure relief device characteristics.
Guidance
Vacuum system personnel should be cognizant of the following guidance.
Guidance
Using a gravity closure device or a flange held in place merely by the vacuum pressure itself may be an acceptable overpressure protection technique. A gravity closure bell jar will lift and vent upon slight overpressures (typically around 2 psig).
In a similar approach, the closure hardware (for example, bolts or clamps) can be intentionally left off of a component, allowing the vacuum pressure alone to supply the sealing force to hold the flange in place and vent upon slight overpressure.
Guidance
The following precautions should be taken when intentionally leaving closure hardware off of a component:
- Flanges should be identified as pressure relief ports so that well-intentioned personnel will not inadvertently replace the closure hardware or otherwise inhibit or restrict the functioning of these devices.
- Components should be located where personnel will not accidentally bump them and vent the system.
- Components should be positioned so that they will not fall or pop off and present a hazard to surrounding equipment or personnel.
Guidance
Overpressure protection devices are not necessary for vacuum systems for which analysis shows that it is impossible to overpressurize the system by any credible accident scenario (e.g., a 2 ft3 [expanded gas volume] lecture bottle connected to a 6 ft3 volume vacuum chamber cannot overpressurize the chamber).
A small-volume chamber (e.g., a section of tubing) can be charged to a particular pressure by the pressure source. This chamber can then be isolated from the pressure source and used to supply gas into the vacuum system. In this approach, the volume limitation is supplied through procedural controls (proper valve sequencing).
The use of a checklist to assure proper sequencing is recommended.
Note: Hardware controls are preferred over procedural controls.
Requirements
Vacuum system personnel shall:
Guidance
Vacuum system personnel should be cognizant that:
- Thermal conductivity vacuum gauges are usually calibrated for air or nitrogen. If a different backfill gas is used, large errors in the pressure readout can exist.
- If helium is used (helium is more thermally conductive than nitrogen or air), the system pressure is actually less than what is indicated. If the backfill gas is argon (a less thermally conductive gas), the system pressure will be significantly higher than what the gauge indicates, and a system overpressurization could easily occur if the operator depends upon the gauge readout to prevent overpressurization.
- If a Pirani gauge, commonly calibrated for nitrogen, is used on a system backfilled with argon gas, the gauge readout will never reach atmospheric pressure, even with large positive internal pressures.
- Transducers that actually sense pressure (force per unit area, e.g.,such as capacitance manometers or Bourdon tube gauges) may be preferable in some applications because they are not dependent on the gas species and are, therefore, less susceptible to readout errors.
Note: Brittle components (e.g., vacuum viewports, glass ion gauges, ceramic feedthroughs, and quartz reactor tubes) are commonly applied to vacuum systems. In some cases, the entire vacuum system may be constructed of brittle material (e.g., a laboratory glassware system commonly used in a chemistry lab). Adequate overpressure protection for systems employing these components is especially important, as is, the protection of personnel.
Requirements
Vacuum system personnel shall locate, shield, or position brittle systems or components away from personnel and equipment that could be damaged if the system or component fails.
Requirements
Vacuum system personnel shall shield brittle components to protect personnel from the fragments of a system failure, and to protect brittle or otherwise fragile components from accidental damage by personnel.
Although shielding is the preferred method of protection, an acceptable alternative is to require personnel to wear safety glasses (or a face shield with safety glasses) when working around unshielded brittle components or looking through an unshielded vacuum viewport.
Guidance
Lexan shields are available through the Just in Time (JIT) contract for standard vacuum viewport sizes. Metal shields are available for glass ion gauges.
Requirements
Vacuum system personnel shall use the same shielding, isolation, and personal protection equipment when dealing with special components constructed of brittle materials as are required for routinely used components.
Note: Vacuum viewports have certain operational high-hazard conditions:
- Backfill or initial roughout operations present abrupt pressure transitions-the likelihood of viewport failure during these transitions is increased. Personnel should avoid exposure to vacuum viewports (or other brittle components) during these transitions.
- Rapidly changing temperatures or temperature gradients can also increase the risk of viewport failure. Avoid vacuum viewports during thermal processes such as system bakeout or exposure to heat sources from laser or ion beams.
Guidance
Vacuum system personnel should use layers of aluminum foil across a vacuum viewport to minimize thermal gradients during the bakeout process.
Requirements
Vacuum system personnel shall:
- Avoid scratching viewport surfaces as this can weaken the material and increase the risk of failure.
- Replace scratched or otherwise damaged viewports.
Guidance
Vacuum system personnel should:
- When mounting viewport flanges, tighten the bolts using small angular turns and follow a regular pattern in order to mate the flange with minimum distortion.
- Be aware that special (nonrated) vacuum system components that may not meet the general requirements for structural integrity or ductility may be used in certain unique applications.
Guidance
An example of a special (nonrated) component is the ultra-thin "window" used on X-ray tubes/detectors or on other detectors for activities such as optical experiments and particle beam analysis.
Requirements
Vacuum system personnel shall:
- Determine the level of rigor for precautionary measures to be applied as a function of the degree of hazards presented by system or component failure.
- Consider the personnel hazards associated with component failure as well as the ramifications on the vacuum system operation and components, such as pumps and ensure that adequate overpressure protection is provided in these cases.
Requirements
Vacuum system personnel shall closely scrutinize vacuum pump applications to ensure safe and reliable operations.
Guidance
Vacuum system personnel should:
- Consider that special ventilation and exhaust scrubbing precautions may be required when pumping high-hazard gases, such as flammables, pyrophorics, toxics, or corrosives.
- Remember that vacuum pumps that pump hazardous gases may retain hazardous residues.
Requirements
Vacuum system personnel shall inform repair or maintenance personnel who may be exposed to hazardous residues of these hazards.
Requirements
Vacuum system personnel shall use the SNL Vacuum Pump Repair Information Form (SF 2001-VPR [Word file/Acrobat file]) to identify hazards and solicit feedback from the repair facility for failure analysis.
Note: The form should accompany vacuum pumps sent out for repair.
Requirements
Vaccum system personnel shall ensure the compatibility of the gases pumped with pump fluids and the pump's materials of construction.
Note: For example, special pump oils are needed to safely pump oxygen.
Requirements
Vacuum system personnel shall determine the vacuum pump failure modes and their ramifications on the vacuum system pressure if pump failure or improper pump connection could pressurize the vacuum system.
Requirements
Vacuum system personnel shall:
- Take appropriate overpressure protection measures if pump failure may induce overpressurization.
- Consider the loss of utilities, such as loss of power or cooling water, on the operation of vacuum pumps and the possible effects on the vacuum system.
Guidance
Vacuum system personnel should use appropriate overpressure protection measures that may include the following:
- Additional labeling of the pump's inlet and exhaust ports if operators could confuse ports
- Confirm the proper pump operation before initial startup, following motor repairs, and following work on the facility electrical system
- Apply suitable overpressure protection devices to the system
A data package:
- Is required for vacuum systems, as for all pressure systems, to document safe design and construction.
- Must contain the facts needed to evaluate the vacuum system.
- Is a permanent record that vacuum personnel keep current with the system modifications.
Requirements
Vacuum system personnel shall develop data packages applicable to vacuum systems according to Chapter 9 of the Pressure Safety Manual.
Maintaining and Referencing Operational Documents in Data Package
Guidance
Vacuum system personnel should consider that the data package is a good place to maintain or reference operational technical work documents (TWDs) such as the following:
- System diagrams
- Procedures
- Checklists that reference procedures, such as valve sequencing operations and gas cylinder changes
Note: See ESH100.2.GEN.3, Develop and Use Technical Work Documents, for information on developing TWDs.
Requirements
The responsible SNL manager, the Pressure Advisor, and the Pressure Installer shall determine the adequacy of and the level of approval for the Data Package.
Requirements
Vacuum system personnel shall identify and characterize the vacuum system in a Data Package including:
- Identify the system and supply a brief system abstract.
- Characterize the system, including information such as the following:
- Manufacturer(s)
- Types of components
- Materials of construction
Guidance
Vacuum system personnel should use the manufacturer's catalog information or operators' manuals as sources of this information including:
- Estimate the system volume, including that of components such as the vessel, plumbing, and pumps.
- If applicable, document the overpressure test that qualifies the system.
Identify Component Automation and "Fail-Safe" Components
Requirements
Vacuum system personnel shall identify the consequences of failure in the data package for the following:
- System or component automation such as the following:
- Microprocessor-controlled systems
- Emergency shutoff valves
- Interfaces to gas monitoring systems
- Pneumatic or solenoid valves designed to be "fail safe."
- The system status upon loss of utilities (for example, power, cooling water, pneumatic pressure for valves, and exhaust or ventilation) as they apply to the pressure safety aspects of the vacuum system.
Requirements
Vacuum system personnel shall list all plausible pressure sources in the data package. Include a listing of the pressure line components and their ratings (for example, DOT cylinders, regulators, valves, and piping or tubing).
Requirements
Vacuum system personnel shall document the following in the data package:
- Overpressure protection device or technique
- Applicable hardware
- Set pressure of relief devices and their flow capacity as applicable to the system's pressure sources
- Consequences of failure
- Personal protective equipment requirements
Requirements
Vacuum system personnel shall identify and give special attention to nonrated components in the data package. Indicate a safe failure mode or shielding provided.
Requirements
Vacuum system personnel shall list components that contain brittle materials and document shielding or procedures that provide for personnel protection.
If the system is predominantly of brittle materials, document the design material specifications and mechanical containment or administrative controls, including physical barriers, to preclude access to the potential hazard.
Requirements
Vacuum system personnel shall describe the vacuum pump system and document the following information in the Data Package:
- Date of installation
- Pressure range
- Maintenance practices
- Maintenance intervals
- Repair information
- Possible hazardous contaminants
- Plausible pump failure modes
Requirements
Vacuum system personnel shall include warnings or special instructions for maintenance or reapplication personnel and identify any hazardous substances that may remain in the vacuum system pumps or components and associated piping.
Requirements
Vacuum system personnel shall, for procedural controls that provide overpressure protection, document the pressure/volume calculations (along with the proper valve sequencing information) in the data package.
Requirements
Vacuum system personnel shall document gas supply lines in the data package covering the overall system, and document the MAWP based on the ratings of the gas line components.
Shane Page, srpage@sandia.gov
Al Bendure, aobendu@sandia.gov
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