Text For Citation: 01 Item/Group: 001 Hazard:

Section 5(a)(1) of the Occupational Safety and Health Act of 1970: The employer did not furnish employment and a place of employment which were free from recognized hazards that were causing or likely to cause death or serious physical harm, in that employees were exposed to fire &/or explosion hazards from combustible dust and from hydrogen gas while working with a 3D printing equipment system in an additive manufacturing facility that fabricated items from combustible metal alloy powders containing titanium, aluminum and other combustible metals ("metals" includes metalloids): The 3D printing equipment system included the following components: 2 - CONCEPT Laser GmbH M2 Cusings [3D Printers] 2 - Rofin-Baasel Lasertech GmbH & Co KG 400 watt Fiber Lasers 2 - TBH GmbH FP 150 EX II 3D De-Dusters 1 - Ruwac Industriesauger GmbH NA35 Wet Separator 1 - CONCEPT Laser QM Powder with Italvibras S.p.A. Electric Vibrator MTF 15 [Sieving Station] 1 - CONCEPT Laser GmbH Lifting Device [Hoist] 1 - Kaeser SM15 Air System (compressor and dryer) 1 - Pressure tank (1000 liters) 1 - 240 liter liquid Argon Tank 1 - Domnick Hunter Division, Parker Hannifin, Ltd MIDIGAS4 Nitrogen Generator (A) Fire &/or Explosion Hazards from Combustible Dust made of Metal Alloy Powders Worksite - On or about 11/5/13, a combustible metal alloy powder fire &/or explosion inflicted life-threatening third-degree burns on the production employee, due to the employer's failure to implement fire &/or explosion preventive and protective measures. (A)(1) CONCEPT Laser M2 Cusing (3D Printer) (A)(1)(i) On or about 11/5/2013, the employer failed to ensure that ignition sources were eliminated while its only production worker handled combustible metal alloy powders in the 3D Printer's Handling Chamber when it was open, during set-up operations that were necessary between production runs (when the Handling Chamber was closed and inaccessible). The employer did not provide and/or ensure use of necessary equipment to dissipate static electricity (electrostatic charges) that could ignite the combustible metal alloy powders it processed, such as ultrafine titanium alloy Ti-6Al-4V, which had a minimum ignition energy of less than 6 milli-joules: (a) The employer did not ensure that its worker used an Electrostatic Discharge (ESD) armband-cable to bond the worker to the 3D printer and eliminate that potential source of electrostatic charge (ignition source). (b) The employer did not ensure that its worker used an Electrostatic Discharge (ESD) cable between the CONCEPT Laser Lifting Device and the 3D printer to bond the Lifting Device to the 3D printer and eliminate that potential source of electrostatic charge (ignition source). (c) The employer did not ensure that its worker used an Electrostatic Discharge (ESD) cable between the Ruwac Industriesauger NA35 Wet Separator and the 3D printer to bond the NA35 Wet Separator to the 3D printer and eliminate that potential source of electrostatic charge (ignition source). (d) The employer did not provide an Electrostatic Discharge (ESD) mat to its worker to eliminate the floor-to-worker electrostatic charge potential. Among other methods, one feasible and acceptable abatement method to correct this hazard is to train the employee in the fire &/or explosion hazards of combustible metal alloy powders, the ignition hazards presented by static electricity, and the proper use of protective measures such as electrostatic charge dissipating equipment; and to provide, require and enforce the use of electrostatic discharge cables and mats. Another feasible and acceptable abatement method is to provide an interlock on the door to the Handling Chamber to ensure that it remains inaccessible until the ESD bonding points on its cabinet are engaged. (A)(1)(ii) On or about 11/5/2013, at the 3D Printer where the only production employee worked, the employer failed to provide a reliable oxidant-inerting system to prevent ignition of a combustible titanium alloy powder fire &/or explosion in (a) the Laser Build Chamber when in operation; and (b) in the 3D printer's Handling Chamber when closed and meant to be oxidant-inerted. The employer used only oxygen sensors; and it had no instrumentation to monitor the argon gas that it used as explosion protection for its employee. Among other methods, one feasible and acceptable abatement method to correct this hazard is to comply with the relevant provisions in NFPA 69 (Standard on Explosion Prevention Systems) (both the 2008 or 2014 editions), such as the following in Chapter 7 "Deflagration Prevention by Oxidant Concentration Reduction" "7.7.1* General. Instrumentation shall be provided to monitor the purge gas being supplied to the distribution system." "A.7.7.1 The objective is to maintain operation outside of the flammable region.... Instrumentation should have redundancy, depending on the criticality of the operation." Two examples of ways to provide such instrumentation are providing the argon supply tank with a load cell and providing the argon supply tank with a reliable level sensor. (A)(2) TBH GmbH FP 150 EX II 3D De-Duster On or about 11/5/2013, beside the 3D Printer that processed combustible dust (titanium alloy powder) there was a dry-type dust collector which presented a fire and/or explosion hazard to the production employee through the combination of these conditions: (a) it was located indoors; (b) its filter operated to it had a reverse pulse filter which would create a combustible dust cloud inside the TBH cabinet when it pulsed to clear itself of the dust; (c) it was not cleared of collected combustible dust daily or even monthly; and (d) its explosion prevention method of using an inert gas to prevent ignition had no instrumentation to monitor the purge gas and no independent instrumentation to monitor the limiting oxygen concentration. Among other methods, one feasible and acceptable abatement method to correct this hazard is to comply with the relevant provisions in NFPA 484 (Standard for Combustible Metals, 2012 edition) and NFPA 69 (Standard on Explosion Prevention Systems) (both the 2008 or 2014 editions), such as the following: From NFPA 484 (Standard for Combustible Metals) Chapter 12 "Titanium" "12.2.4.6 Dry-Type Dust Collectors." "12.2.4.6.3 Dry-type dust collectors for combustible metal dust material shall be located outside buildings" "12.2.4.6.8 Dust shall be removed from the dry collectors at the end of each workday" From NFPA 69 (Standard on Explosion Prevention Systems) Chapter 7 "Deflagration Prevention by Oxidant Concentration Reduction" "7.7.1* General. Instrumentation shall be provided to monitor the purge gas being supplied to the distribution system." "A.7.7.1 The objective is to maintain operation outside of the flammable region.... Instrumentation should have redundancy, depending on the criticality of the operation." "7.7.2 Systems Operated Below the Limiting Oxidant Concentration (LOC): "7.7.2.1 Instrumentation shall be installed in as many points as necessary to ensure the desired oxidant concentration reduction within the protected system." (A)(3) Ruwac Industriesauger GmbH NA 35 Wet Separator [Vacuum] (A)(3)(i) On or about 11/5/2013, the employer's failure to clean and maintain the Wet Separator in accord with the manufacturer's directions ? a task requiring two people due to the configuration and weight of the Wet Separator - allowed the mixing of incompatible combustible metal powders (such as iron oxide with titanium &/or aluminum), thereby creating conditions for a thermite reaction and ignition of a combustible metal dust fire &/or explosion. The employer had only one production employee and using the Wet Separator was part of his regular duties. Among other methods, one feasible and acceptable abatement method to correct this hazard is to comply with the manufacturer's instructions to empty and clean the Wet Separator at the end of each shift when working with powder containing aluminum or titanium. (A)(3)(ii) On or about 11/5/2013, the employer's failure to ensure that the liquid in the Wet Separator was maintained at an adequate level created conditions for formation of a combustible metal dust cloud inside the Wet Separator, which an employee used as part of his regular duties. Among other methods, one feasible and acceptable abatement method to correct this hazard is to add an interlock on the Wet Separator to prevent start up in the event that there is an inadequate level of liquid in it. (A)(4) CONCEPT Laser QM Powder with Italvibras S.p.A. Electric Vibrator MTF 15 [Sieving Station] (A)(4)(i) On or about 11/5/2013, the employer failed to ensure that static electricity ignition sources were eliminated while its worker transferred combustible metal alloy powders between the Sieving station and the CONCEPT Laser Lifting Device. The employer did not provide and/or ensure its employee's use of an Electrostatic Discharge (ESD) armband, cable or mat to dissipate static electricity (electrostatic charges) that could ignite the combustible metal alloy powders being transferred in &/or out of the Sieving station, such as the ultrafine titanium alloy Ti-6Al-4V, which had a minimum ignition energy of less than 6 milli-joules. Among other methods, one feasible and acceptable abatement method to correct this hazard is to provide electrostatic discharge cables and mats, train employees in the combustible metal powder ignition hazards presented by static electricity and proper use of electrostatic charge dissipating equipment, require and enforce the use of electrostatic discharge cables and mats. Another feasible and acceptable abatement method is to provide an interlock on the unit to ensure that it cannot operate until ESD bonding points on it are engaged. (A)(4)(ii) On or about 11/5/2013, the employer exposed its production worker to fire &/or explosion hazards by locating the Sieving station ? which sifted very fine combustible metal alloy powders - directly adjacent on one side to its production employee's workbench and on the other side to the open shelves that stored combustible metal powders in bottles, near an ordinary shop vacuum which posed a potential ignition source. Among other methods, one feasible and acceptable abatement method to correct this hazard is to: locate the Sieving station in an area away from the employee's workbench; store combustible metal powders in listed fire resistant cabinets when not in use; and remove the ordinary shop vac. (B) Explosion and Fire Hazards from Hydrogen (B)(1) The employer's titanium and aluminum alloy powders, in addition to being combustible, would react with water to form hydrogen gas, which is explosive. Consequently, the employer's use of a water sprinkler system, coupled with its pre-existing failure to disclose the presence of water-reactive titanium and aluminum alloy powders to the Woburn Fire Department, created a hydrogen explosion hazard to which its employee was exposed when a combustible metal dust fire and explosion occurred, burning him and bringing the Fire Department to put it out. Among other methods, one feasible and acceptable abatement method to correct this hazard is to do a hazards analysis as referenced in NFPA 484 (Standard for Combustible Metals, 2012 edition) section 15.3 to determine if the sprinkler system poses a more severe hazard and if so, take appropriate action as needed to decommission/deactivate it in cooperation with the Woburn authorities and in concert with maintaining up-to-date disclosure to the Woburn authorities of all materials onsite where water and other routine firefighting measures are dangerous or ineffective. (B)(2) Ruwac Industriesauger GmbH NA 35 Wet Separator The production employee was exposed to hydrogen explosion hazards in the Wet Separator used to collect titanium and aluminum alloy powders due to the water-reactive nature of these materials in the following parts of the Wet Separator: (a) in the Wet Separator tank which used water and (b) in the demisting mat filter which retained moist water-reactive metal powder. Among other methods, one feasible and acceptable abatement method to correct this hazard is to implement the following measures: train the employee on hydrogen hazards and how they can occur in the processing combustible dust composed of water-reactive materials; use a liquid in the Wet Separator that will not react with titanium and aluminum alloy powders; perform daily checks on the Wet Separator's hydrogen degassing value to ensure that it is functioning; eliminate or daily remove and dry the Wet Separator's demister mat; provide and use hydrogen level sensors around the Wet Separator; provide and use a method to channel degassed hydrogen outside.