Att C - Tech Specification DHA.pdf

EMD-SS-2025-08

ORNL/LTR-2025/3763

ORNL IS MANAGED BY UT-BATTELLE LLC FOR THE US DEPARTMENT OF ENERGY

Dust Hazard Analysis for Metal Powder Atomization and Handling at

CFTF

David Rohrig

March 2025

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EMD-SS-2025-08

ORNL/LTR-2025/3763

Defense Manufacturing Group

DUST HAZARD ANALYSIS FOR METAL POWDER ATOMIZATION AND

HANDLING AT CFTF

Author(s)

David Rohrig

Month Year

March 2025

Prepared by

OAK RIDGE NATIONAL LABORATORY

Oak Ridge, TN 37831 managed by

UT-BATTELLE LLC

for the

US DEPARTMENT OF ENERGY

under contract DE-AC05-00OR22725

Signatures:

David Rohrig – System Safety Analyst and Author

Luke Platfoot – Fire Protection Engineer - LMD

Alan Liby – R&D Process Expert

Approver: Merlin Theodore– Group Leader - MSD iii

Contents ABBREVIATIONS AND ACRONYMS .................................................................................................... iv

1. Introduction

1.1 Background

1.2 Purpose

2. Dust Hazard Requirements

3. Dust Hazard Identification

3.1 Planned Metal Powders

4. System Design and Hazard Mitigations

5. Dust Hazards

6. Combustible Dust Controls

6.1 Building Design

6.1.1 Construction

6.1.2 Life Safety

6.1.3 Separation or Segregation from other Areas

6.1.4 Electrical System

6.1.5 Fire Protection

6.2 Process Controls

6.2.1 Inert Atmosphere

6.2.2 Wet-Type Air-Material Separator (Dust Collector)

6.2.3 Grounded Equipment

6.2.4 Personnel Grounding

6.2.5 Rigid Intermediate Bulk Container

6.2.6 Equipment Interlocks

6.2.7 Down-Draft Bench

7. Operations

7.1 Operational Administrative Controls

7.2 Spill Clean-up

7.3 Wet Dust Collector Maintenance

7.4 HEPA Vacuum Maintenance

8. Team Members

9. References Appendix A. SYSTEM DIAGRAMS ....................................................................................................... A-2 iv

ABBREVIATIONS AND ACRONYMS

AMS Air-Material Separator DHA Dust Hazard Analysis CFTF Carbon Fiber Technology Facility HMMIS Hazardous Materials Management Information System NFPA National Fire Protection Association ORNL Oak Ridge National Laboratory PPE Personal Protective Equipment

1. Introduction

1.1 Background

The Defense Manufacturing Group is planning to create metal powders for use in additive manufacturing processes. These powders will be created through atomizing molten metal in an inert atmosphere, solidifying the particles during flight and then collected in an inert intermediate bulk container (IBC). The powder is moved to a sieving process to select the preferred particle sizes, sampled for quality testing, blended for homogeneity and packaged for use in other processes. The remaining powder is recycled.

1.2 Purpose

This Dust Hazards Analysis (DHA) is developed for the purpose of identifying and evaluating the hazards, assessing risks, and identifying the engineered and administrative controls necessary for the protection of the dust hazard associated with the storage, handling, and use of combustible metal powders.

A DHA is required by NFPA 484 (7.2.1) and NFPA 652 (7.1.1) to evaluate the fire, deflagration, reactivity, and explosion hazards and to provide recommendations to manage the hazards.

The combustible metal hazards are associated with the commercially available atomizer system and subsequent handling of the atomized metal powder.

The hazards evaluated by this analysis are specific to fire, deflagration, and explosion of metal dusts.

Additional hazards are not addressed herein, such as pressure systems and industrial hygiene risks (e.g., high noise, skin or respiratory exposures) and are addressed in other work planning documents.

Powders are stored and transported only in covered or sealed containers; thus, deflagration venting is not required per NFPA 484, 9.2.7.5.5.

The design of the fire and explosion safety provisions are to be based on this hazards analysis per National Fire Protection Association (NFPA) 484, Section 7.2.

The NFPA standard requires that the dust hazards analysis shall be maintained for the life of the process, with a review and update every 5 years.

2. Dust Hazard Requirements

Combustible metal dusts can present fire and explosion hazards under certain process conditions. The fire protection requirements applicable to the atomizer process are driven by 10 CFR 851, Worker Safety and Health Program, DOE Order 420.1C, Change 3, Facility Safety, and DOE Standard, DOE-STD-1066- 2016, Fire Protection, which provides acceptable methods for meeting the DOE Order requirements. In accordance with the DOE requirements, facilities must be constructed to meet the applicable codes and standards in effect when the design criteria are approved. The following editions of NFPA standards are applied as revised codes of record to the atomizer process, to be located in CFTF:

• NFPA 484, Standard for Combustible Metals (2022)

• NFPA 652, Standard on the Fundamentals of Combustible Dust (2019)

• NFPA 654, Standard for the Prevention of Fire and Explosions from the Manufacturing, Processing, and Handling of Combustible Particulate Solids (2020)

These standards cross-reference one another for requirements applicability. The administrative chapters in each of these standards provides additional discussion of the applicability of the standards in relation to one another. Each of these standards contains requirements for a hazard analysis to address the fire and explosion hazards of combustible metals or dusts.

The maximum allowable quantities (MAQs) of hazardous materials, including metal powders (flammable solids) are established by the International Fire Code (2024 Edition). The MAQs provide the basis for ORNL hazardous material limits that are tracked within the ORNL Hazardous Materials Management Information System (HMMIS). For flammable solids (i.e., combustible metals) qualitative limits are established and documented in the CFTF Facility Use Agreement (FUA).

3. Dust Hazard Identification

3.1 Planned Metal Powders

ORNL researchers are planning to use this process to create high temperature alloy powders. The scope of this analysis includes the following materials. The process for approving new powders is found in the management of change section.

• Hafnium • Titanium

• Nickel (inorganic) • Tantalum

• Niobium • Tungsten

• Steel, with iron and nickel • Zirconium

• Stainless Steel, with iron

The desired powders from this process range 10 to 150 µm (micrometer). Some smaller powders will also be created, which will likely test positive for a combustible dust classification. NFPA 484 provides two options for determining the applicability:

Option 1 (NFPA 484, 5.2.4.1 & 5.2.4.2) Specific materials which can be documented through testing of combustibility and explosibility as not meeting the definition for these hazards can be excluded from the requirements of NFPA 484. Materials proven by testing to be combustible shall invoke the full scope and requirements of NFPA 484.

Option 2 (NFPA 484, 5.2.4.3) Wherever the documentation of analytical test results is lacking, the requirements of NFPA 484 apply.

Due to the experimental nature of the process and the high likelihood that smaller particles (more combustible) will be produced, ORNL will select Option 2 and apply NFPA 484 standard in full.

Compliance is achieved through prescriptive provisions in accordance with NFPA 484. The ORNL atomizer process will not utilize any alkali metals (i.e., elements occupying Group IA (1) of the periodic table) such as cesium, francium, lithium, potassium, rubidium, sodium and alloys of these metals.

Therefore, NFPA requirements specific to alkali metals are not reviewed in this DHA.

Additional materials beyond those listed above shall be reviewed to verify if additional controls are required. All materials used will still need to be evaluated and approved for other hazards such as personnel exposure per the work planning process.

4. System Design and Hazard Mitigations

The process flow and equipment layout are shown in Appendix A.

Atomizer The Atomizer is configured to operate in either of two modes, each using alternative heating methods to produce molten metal. One mode, REGA (Retech Electrode Gas Atomization) feeds a 50 mm to 100mm diameter rotating metal electrode vertically downward through an induction coil. Molten metal drips from the lower tip of the electrode. In the second mode, PGA (Plasma Gas Atomization) metal chunks or briquettes are melted on a water-cooled hearth using a plasma arc torch and then poured from the hearth in a molten stream. In each mode, the molten metal falls through an atomization die and is contacted with high pressure argon to disperse the molten metal stream into small metal droplets that then solidify to powder as they drop through an argon-filled chamber. The entire process is enveloped in a high-purity argon atmosphere to avoid oxidation of the powder. The powder particles are collected at the bottom of the cyclone separator in an Intermediate Bulk Container (IBC). The argon is then exhausted into a wet dust collector prior to be exhausted outside the facility. Valves above the powder containers are then closed. The container is then disconnected from the cyclone separator and moved to a separate area where the metal powder in the container may be passivated by adding a mixture of argon and air in a controlled manner through a port near the bottom of the container.

Powder Handling Powders are moved between processing steps in sealed and inerted Rigid Intermediate Bulk Container

(RIBC).

Sieving The sieving equipment is designed to separate the powders based on size. Argon is passed through entire sieving system to maintain an inert atmosphere. The “on-spec” powders are transferred to the decanting process and the “off-spec” powders are transferred to the compactor in a sealed container.

Decanting The decanting process dispenses a specified amount of powder to be used in follow-on powder handling processes. Argon is passed through the decanter to maintain an inert atmosphere.

Blending After sieving to desired particle size, multiple atomization runs are combined in the blender to achieve the desired particle size distribution of the product. Argon is passed through the blending unit to maintain an inert atmosphere while blending. The powder is inertly transferred through a valved flange into the blender.

Packaging The powders are transferred from the blender into inert containers for shipment to follow-on processes.

Packaging will be done in an argon atmosphere glovebox through an inert hopper to maintain fire safety and product quality. These containers are sealed and either immediately shipped or stored in the storage room.

Compactor The compactor is used to consolidate metal powders and chips into a form that can be remelted in the Electron Beam Melter or Plasma Arc Melter. The compactor operates in an inert atmosphere and utilizes hydraulic pressure to compact the material.

Down Draft Table The down draft table is used to clean or service system components that may have small quantities of metal powders. The exhaust from the table is routed through the wet dust collector.

Electron Beam Melter/ Plasma Arc Melter The Electron Beam Melter (EBM) and Plasma Arc Melter (PAM)are used to recycle powder for this process. The EBM and PAM does not contain combustible dust and is outside the scope of this hazard analysis.

5. Dust Hazards

Each of the process steps have been evaluated to determine if there is a risk of a dust explosion. The ingredients for a dust explosion include suspended dust and oxidizing atmosphere and ignition. The hazard and the controls for each of the process steps are summarized in Table 1.

Table 1. Dust Hazards

No Process Step Quantity Suspended Dust

Oxidizing Atmosphere

Ignition Explosion Control Measures

1 Atomizer >20 kg Yes No Yes – Molten Metal

Inert Atmosphere

Inert Atmosphere Interlock

Ventilation - Wet AMS

2 IBC – Moving and Storage

>20 kg No No No Inert Atmosphere

Grounded equipment

3 Transfers >20 kg Yes No No Inert Atmosphere

Grounded equipment

4 Sieving >20 kg Yes No No Inert Atmosphere

Inert Atmosphere Interlock

Grounded equipment

Sealed or explosion proof electrical

5 Decanting >20 kg Yes No No Inert Atmosphere

Grounded equipment

Sealed or explosion proof electrical

6 Packaging >20 kg Yes No No Inert Atmosphere

Grounded Equipment

7 Compacting >20 kg No No No Inert atmosphere 8 Cleaning –

Down Draft Table

<0.5 kg Yes Yes No Grounded equipment

Grounded Personnel

Non Sparking Tools

Non-dust generating techniques

Ventilation (Down Draft) with Wet AMS

9 Cleaning – Small spill of powder outside container

<0.5 kg Yes Yes No Grounded Personnel

Non-dust generating techniques

10 Cleaning – Large spill of powder outside container

>.5 kg Yes Yes No Grounded Personnel

Non-dust generating techniques

Spill clean-up procedure

6. Combustible Dust Controls

This section specifies the controls that are required for this process.

6.1 Building Design

6.1.1 Construction

The atomizer process is in a facility of Type II-B construction. The building is a steel framed structure with a concrete slab floor.

6.1.2 Life Safety

The atomizer will be in a space that is classified as F-1 occupancy per the International Building Code – 2018 with life safety and egress in accordance with NFPA 101, 2021 edition for an Industrial occupancy.

The power handling and storage will be located in an H-3 occupancy per the International Building Code

– 2024 with life safety and egress in accordance with NFPA 101, 2021 edition for an Industrial occupancy. The storage is in a separate room within the H-3 occupancy in accordance with NFPA 484

17.4.1.10. This H-3 allows for storage of in-process material as well as ready for shipment materials.

6.1.3 Separation or Segregation from other Areas

The atomizer and powder handling equipment will be installed along the east wall of the high bay towards the south end of the building as shown in Figure A3. This location is separated of other processes by the aisle in the building and the walls of the Powder Handling Room. The argon gas for these processes will be fed from a liquid tank and vaporizer located on the west side of the building near the north end.

The atomizer and powder handling process deflagration hazards are mitigated as detailed in this analysis eliminating the need for detachment, separation, or segregation of hazard area from other hazard areas (NFPA 484, 9.2.1, 9.2.6.1). Based on the small quantities of combustible powders outside of an inert atmosphere and the noncombustible construction of the building structure, the H-3 powder handling space (1-hour separation) provides an adequate segregation from other hazards within the building.

6.1.4 Electrical System

The powder handling room shall be classified as Class II Division II Group E in accordance with NFPA

70. All powder handling will be done in an inert environment. During cleaning operations and in the case of a spill there is a potential for dust to be exposed to an oxidizing atmosphere. Similarly, for the atomizer, the area around the powder container at the bottom of the cyclone separator, and the lower cone

– lower flange of the atomization column (when opened) has a potential for small quantities of combustible dust to be exposed to an oxidizing atmosphere. Based on this hazard, the area withing 10 feet of this area shall be classified Class II Division II Group E in accordance with NFPA 70. This control in addition to the controls for electrostatic discharges will limit ignition sources. (NFPA 484 12.4)

6.1.5 Fire Protection

The powder handling room will be protected with a combination fixed-temperature and rate-of-rise thermal (i.e., heat) detector on the ceiling and will be listed for use in a Class II, Division 2, Group E environment. As required by NFPA 484, the room shall not be sprinklered. NFPA 484, 10.5.1.1 specifically prohibits automatic sprinkler protection in areas where combustible metals are produced or handled. This sprinkler prohibition is echoed in NFPA 652, 9.8.5.2. The Department of Energy (DOE) Order 420.1C, allows that fire suppression be omitted in certain areas where the relief is allowed by

NFPA.

For manual fire suppression a Class D portable fire extinguisher shall be located inside the room for response by personnel working with combustible metal powder. Placement of the extinguisher will meet NFPA 484 and its reference to NFPA 10. Special markings shall be provided to emphasize which hazard each Class D extinguisher is suitable to suppress. Trained employees are permitted to fight incipient-stage fires, provided the fire can be controlled with portable extinguishers or other dry extinguishing agent (NFPA 484 10.5.4.1 and A10.5.4.1). Combustible-metal fires beyond the incipient stage shall be fought by professional fire fighters (NFPA 484 10.5.4.3).

The following are not to be used as extinguishing agents on combustible-metal fires because of adverse reactions or ineffectiveness:

(1) Water

(2) Foams

(3) Halon

(4) Carbon dioxide

(5) Nitrogen (IG-100), but can be considered for iron, steel, and alkali metals

(6) Halocarbon Clean Agents

The general area fire extinguishers are ABC dry-chemical type and are not to be used as an extinguishing agent on a combustible metal fire but are suitable for other classes of fires in the area where combustible metals are present. Fire-extinguishing agent expellant gases (typically nitrogen) shall be compatible with the combustible metal. Where Class A, Class B, or Class C fire hazards are in the combustible-metal area, extinguishers suitable for use on such fires shall be permitted, provided they are marked “Not for Use on Combustible-Metal Fires.”

6.2 Process Controls

6.2.1 Inert Atmosphere

Argon gas will be used throughout the atomization and powder handling process to protect the powder from oxidation and to protect against fire or explosion. Argon gas will be fed into the powder handling equipment and vented through an oil bubbler that will provide indication that equipment has been inerted.

The atomizer and sieving machine will have interlocks. (see 6.2.6)

6.2.2 Wet-Type Air-Material Separator (Dust Collector)

A Wet-Type Air-Material Separator (AMS) shall be provided for the process exhaust from the atomizer and the down-draft bench. This exhaust will be directed outdoors and discharge to a safe location (10 ft above adjacent roof, >3000 fpm, > 50 ft from air intakes). This AMS shall be designed and operated in accordance with NFPA 484 13.2.4.5. The equipment shall be interlocked to the atomizer in accordance with NFPA 484 13.2.4.5.8. The sieving, IBC evacuation, compaction process equipment may also be attached to the AMS.

6.2.3 Grounded Equipment

Equipment used throughout the atomization and powder handling process must be electrically grounded or bonded to make sure ignition sources (static) are controlled. Powder containers must be conductive and covered when in storage or in transit (NFPA 484, 17.4.1.4, 18.4.1.4), except for powders delivered in supplier container.

6.2.4 Personnel Grounding

Personnel that are interacting with the powder will wear grounding straps or use grounding mats to control ignition sources. In addition, staff will be wearing anti-static clothing and footwear. This control will primarily be used during cleaning processes. (NFPA 484 9.4.7.5.1)

6.2.5 Rigid Intermediate Bulk Container

Conductive bulk containers (NFPA 484 9.4.7.7) will be used to move powders between process steps.

These containers can maintain an inert atmosphere as well as be grounded to protect against ignition of the contents. Powder containers must be conductive and covered when in storage or in transit (NFPA 484, 17.4.1.4, 18.4.1.4). When powder is being transferred between containers, the containers must be bonded and grounded (NFPA 484,17.4.1.5, 17.4.1.6, 18.4.1.5, 18.4.1.6).

6.2.6 Equipment Interlocks

The atomizer and the sieving machine have interlocks to restrict start-up and initiate shut down of equipment if oxygen levels are above 2%. Operation is expected at lower oxygen levels to assure product quality. The 2% limit provides an acceptable margin relative to the limiting oxygen concentration for the metals being used. This will limit the operation of this equipment in an oxidizing atmosphere. In addition, the atomizer operation will be interlocked to the AMS operation.

6.2.7 Down-Draft Bench

A down-draft bench will be used for cleaning components from various process equipment. The down-draft bench will be connected to the wet AMS prior to be exhausted. Small quantities of dust will be collected by the bench. Operators will utilize personal grounding during use. Operators will also require appropriate PPE to protect from exposure to the metal powders.

7. Operations

7.1 Operational Administrative Controls

The atomizer area and powder handling room are areas where combustible dust hazards may be present and there is a potential for combustible metal dust to build-up on the surfaces inside the room. Based on the presence of a dust hazard, these spaces could contain a potential deflagration hazard if the combustible dusts are allowed to accumulate over time. To manage this hazard, strict administrative controls will be in effect to limit the build-up of transient combustible dusts.

These controls include housekeeping by sweeping or wiping down of walls, floors, and horizontal surfaces followed by clean-up of residual dusts with an approved explosion-proof vacuum. In addition, ignition sources within the space will be strictly controlled by engineered controls (i.e., Class II, Division 2, Group E electrical) and other administrative controls (e.g., use of non-sparking tools). During operation of the system, material in the atomizer and powder handling equipment is not exposed to oxygen, and therefore does not pose a flammability / combustibility hazard.

Engineered and administrative controls will be in place to mitigate the fire and explosion hazards of the combustible dust materials, including:

• Equipment has been designed to confine and exhaust dusts.

• Accumulation of dust on any portion of the equipment and fixtures will be minimized via an engineered wet-type dust collection system, proper dust handling procedures, and equipment layout.

• The interior surfaces of the equipment and the powder handling room will be regularly and systematically cleaned by trained qualified operators wearing proper personal protective equipment (PPE) and taking care to prevent excessive dust suspension. These periodic cleaning of fugitive dusts from inside the room and equipment surfaces will be accomplished by the following:

o Use conductive, non-sparking scoops and soft brooms or brushes with natural fiber bristles. Collected dust from vacuum cleaner and/or scoops are to be consolidated within the room and removed in sealed containers for disposal.

o Use a dedicated vacuum cleaner designed specifically for handling combustible metal dusts for residuals leftover after manual scooping or sweeping.

o Use wipes with isopropyl alcohol for minor dust accumulations and residuals that remain after sweeping and vacuuming.

o Use of personnel grounding to limit ignition sources.

General storage of ordinary combustibles is not allowed inside powder handling room.

A Standard Operating Procedure (SOP) shall be authored providing operational and safety procedures related to the atomizer and powder handling process. Within the SOP are:

• Operating procedures and practices

• Personal Protective Equipment (PPE) requirements

• Inspections & Maintenance procedures

• Training and qualification requirements

7.2 Spill Clean-up

A spill of material outside of the inert atmosphere provides the highest potential for a fire or explosion.

The most likely spill scenario is the release of a small quantity of material when equipment and containers are connected and disconnected. Due to the small quantity of material exposed, the magnitude and likelihood of a fire is expected to be very low. These types of spills can be handled with the routine maintenance controls outlined in Section 7.1. A larger spill is much less likely but has the potential to be very dangerous if not treated carefully. A procedure will be developed prior to starting operations for larger spill clean-up that includes response planning to address dust dispersion, ignition control, exposure control (e.g. PPE, ventilation), waste disposition, and emergency response.

7.3 Wet Dust Collector Maintenance

• Routine inspection and cleaning as required of dust accumulation in the outlet portion of the dust collector and the exhaust vent duct (NFPA 484,13.2.4.5.5).

• Semiannual inspection of inlet duct, exhaust duct, and blower to assure that combustible metal dust is not accumulating (NFPA 484,13.2.4.4.15.5).

• Sludge shall be removed from the AMS whenever the AMS is to remain inoperative for a period of 24 hours or more (NFPA 484,13.2.4.5.10.5).

7.4 HEPA Vacuum Maintenance

• When the portable HEPA vacuum cleaner bags need to be emptied, the contents should be emptied into an intermediate waste container inside of the powder handling room.

• Maintenance of the portable HEPA vacuum and waste handling requires a procedure. (NFPA 484, 10.4).

8. Team Members

Lyle Brunke – System Safety Dan Johnson – Fire Protection Alan Liby – R&D Process Expert Luke Platfoot – Fire Protection

Paul Prichard– R&D Process Expert David Rohrig – System Safety Merlin Theodore– R&D Process Expert

9. References

NFPA 10, Standard on Portable Fire Extinguishers (2022)

NFPA 101, Life Safety Code (2021)

NFPA 400, Hazardous Material Code (2022)

NFPA 484, Standard for Combustible Metals (2022)

NFPA 652, Standard on the Fundamentals of Combustible Dust (2019)

NFPA 654, Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing, and Handling of Combustible Particulate Solids (2020)

NFPA Guide to Combustible Dusts (2012)

APPENDIX A. System Diagrams

APPENDIX A. SYSTEM DIAGRAMS

Figure A1. Powder Handling Process Flow

Figure A2. Equipment Layout

Figure A3. Building Layout

Appendix A. SYSTEM DIAGRAMS