Printing Our Way to SafetyApplications of 3-D Printing in Lockout/Tagout
BY PHIL CLARK AND GUIDO BENDER
Controlling hazardous energy in the workplace is of paramount importance. This sounds obvious, but when OSHA originally enacted legislation back in 1971 there was no consensus standard for lockout/tagout (LOTO)—a procedure intended to ensure that equipment can’t be started when undergoing maintenance. Elements of LOTO appeared in other regulatory standards of 29 CFR 1910 (for example, woodworking, welding, and textiles) but were plagued with inconsistencies. Even when injuries related to hazardous energy occurred and were
cited under the General Duty Clause, they often were not enforced because control of hazardous energy was not a “recognized” hazard.
LEVERAGING TECHNOLOGYTechnology has advanced to the point where many of the barriers to achieving a full lockout condition have been eliminated. Since the formalization of the 29 CFR 1910.147
Control of Hazardous Energystandard in 1989, there have been steady advances in both the development of generic LOTO control devices and the manufacturing industry’s willingness to engineer hazards out of the equipment. Examples of these controls include points of isolation on hazardous equipment that are designed to accommodate a lock and the physical separation of high hazard areas from low hazard areas.
And yet a large number of systems and processes remain incredibly difficult or impossible to confidently render inoperable with physical locks. OSHA accommodates these challenges by allowing workers to “tagout” pieces of equipment as long as they achieve an “equivalent” level of protection. But equivalent protection is a misnomer—it is exceptionally difficult to convince a safety professional or compliance officer that a tag can achieve the same level of protection as a lock. The foremost desire of safety and health professionals is to find a way to lock out equipment to isolate the hazard.
LOCKOUT VS TAGOUTAt the National Renewable Energy Laboratory’s (NREL) Energy Systems Integration Facility (ESIF), researchers in the Fuel Cell Development and Testing Laboratory (FCDTL) test and advance hydrogen fuel cell and electrolysis technologies for numerous applications. Hydrogen fuel cell devices are tested for durability, longevity, and contamination performance on dedicated equipment that is plumbed with a variety of gas lines (for example, hydrogen, carbon monoxide, oxygen), all of which may need to be isolated and rendered inoperable during equipment service and maintenance. While these gas lines were plumbed into the lab with impressive space-conscious precision, the valves were clustered together so tightly that generic lockout/tagout devices could not fit around the closed valves (see Figure 1).
PHIL CLARK, MS, CIH,is a point of contact for environment, safety, and health at the National Renewable Energy Laboratory’s Energy Systems Integration Facility in Golden, Colo. He can be reached at (303) 384-7240 or
Dr Ing, is a senior scientist at the National Renewable Energy Laboratory. He manages the Fuel Cell Development and Testing Laboratory and is involved in many aspects of hydrogen fuel cell and water electrolysis research and development. He can be reached at (303) 275-3810 or
Figures 1–3. Left to right: swage valves so tightly clustered that they cannot accommodate generic LOTO devices; examples of 3-D printed control devices, customized for the equipment; examples of control devices printed at NREL.
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Instead of accepting the inability to lock out with generic LOTO devices and resorting to a tagout-only isolation, our team discussed the possibility of cheaply designing and manufacturing custom lockout devices to isolate the valves. The discussion quickly turned toward utilizing a 3-D printer to prototype the desired custom lockout devices. After measuring the valves, testing with an extrusion 3-D printer, and creating a few design iterations, the team realized that the 3-D prints themselves had the potential to suffice as the final control devices. As guidance for our decision, we turned to OSHA’s Protective Materials and Hardware requirements in 29 CFR 1910.147(C)(5). That portion of the standard establishes three clear expectations with which devices must comply:
- durability: devices must be capable of withstanding the environment to which they are exposed
- standardization: devices must be standardized on at least one of three criteria—color, shape, or size
- substantiality: devices must be substantial enough to prevent removal without excessive force (for example, use of bolt cutters)
It was clear that our devices were durable for the environment in which they were being used, were capable of being standardized (for example, they are red in color and sized for specific valves), and were surprisingly substantial. (Note that the design of the device and selection of materials are critical considerations for achieving substantiality.) Our team was satisfied that we had met the intent of the Protective Materials and Hardware requirement, so we used the prints as our final control devices. (Figure 2 illustrates one application of the device.)
After the initial successful isolation of the gas valves with 3-D prints in the FCDTL, other departments within NREL began leveraging this technology for other equipment LOTOs around the complex. (Figure 3 shows a selection of devices printed at NREL.)
COSTS AND BENEFITSThe obvious benefit of utilizing 3-D printed LOTO devices is the customization. But is in-house development worth the trouble? For our control devices, we calculate the cost of the 3-D prints as a function of design and printing—design costs are directly proportional to labor (time spent collecting field measurements; CAD development time), while printing costs are largely commodity driven (print size and filament cost; purchase of or access to a 3-D printer). Labor costs can vary greatly with experience. Factoring in the costs of labor, material, and the printer itself, and with the use of free CAD development software (we use Google SketchUp), we estimate that we can produce thirty 3-D prints for approximately $14 per unit (a single 3-D print would cost between $100 and $160).
To fully assess the return on investment from developing 3-D prints, it is important to consider the costs involved in not locking out a device and instead developing a written plan proving equivalency by using tagout alone. Tagout costs alone may include the following (costs are conservatively estimated for administratively controlling the process detailed above):
$40 for one hour of additional work.Documents take time to develop. Complex lockout/tagouts require equipment-specific procedures (ESP), but tagout-only procedures take on average twice as long to develop as basic lockout ESPs.
$40 for one hour of additional work (removal and reassembly) and about $100 of extra equipment downtime.Workers may be required to remove components to make a system safe (for example, air-gap and cap gas lines, or remove valve handles), thus significantly increasing both the worker’s effort and system downtime.
Consequence of error:
unknown.How much would it cost the organization if an incident occurred? Would failure result in a minor burn to a worker’s finger, or lead to multiple casualties? Human error is more likely for every additional procedural step beyond simple application of a lock. A hydrogen or carbon monoxide-loss event could be catastrophic.
The estimated costs discussed in this article are specific to our team’s project and err on the conservative side. Even so, the cost of developing one custom 3-D print is competitive with the administrative cost of developing a tagout-only application. And the cost of printing multiple 3-D devices eventually becomes competitive with generic LOTO devices.
AN EFFICIENT SOLUTIONThere is unlimited potential for utilizing 3-D printing to improve workplace safety. 3-D printing has allowed our research group to create safe-to-work environments with confidence, knowing that hazardous energy associated with the equipment maintenance is safely isolated. After the initial investment of learning a new piece of equipment and software, the prints have allowed our team to address safety problems quickly, creatively, and more cheaply than using an off-the-shelf control device, while better meeting the intent of the OSHA standard.
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Under strong demand from the automotive industry, the American National Standards Institute (ANSI) published its Z244.1 standard, Control of Hazardous Energy, in 1982. This standard greatly advanced OSHA’s ability to recognize the hazard under the general duty clause and was ultimately used as the template for developing OSHA’s own regulatory language. In 1989, the Control of Hazardous Energy standard (29 CFR 1910.147) was finally adopted as law.
OSHA estimates that 122 fatalities, 28,400 lost workday injuries, and 31,900 non-lost workdays are prevented each year because of the introduction of the Control of Hazardous Energy standard (that is, LOTO). But even with regulation, LOTO injuries still make up approximately 10 percent of serious manufacturing accidents and accounted for 23 percent of the fines assessed to the manufacturing industry in 2016.