in Vol. 19 - September Issue - Year 2018
Safety Is Integral During Abrasive Blasting: Wetblasting, Combustible Dust, Blast Room Ventilation Rates, and Other Safety Issues

Tom Enger is Director of Product Safety at Clemco Industries, the world’s leading manufacturer of compressed-air-powered abrasive blasting equipment.

Clemco’s Contractor Blast Machines have numerous upgrades for the contactor market. The machines come in 2, 4, and 6 cu ft sizes. The 6 cu ft model is pictured above.

Clemco began manufacturing blast machines in the 1940s. Its line of Classic Blast Machines range in size from ½ cu ft to 20 cu ft. The 6 cu ft model, pictured above, is the most popular.

Clemco offers numerous safety and comfort accessories.

Inside a Clemco PDQ™ Blast Room; these are less expensive than engineered blast rooms because they are predesigned.

Outside a Clemco PDQ™ Blast Room. These blast rooms come equipped with either a Pneumatic M-Section® or Mechanical partial-floor recovery system.

Clemco blast cabinets are marketed under the ZERO brand. Pictured left is a suction blast cabinet from ZERO’s ShopMate line. Pictured right is an ergonomic pressure blast cabinet from ZERO’s Pulsar line.

MFN had the pleasure of chatting with Tom Enger, Director of Product Safety at Clemco Industries, the world’s leading manufacturer of compressed-air-powered abrasive blasting equipment. Mr. Enger (known as “the safety guy” at work) shared his wealth of knowledge about current safety issues in the abrasive blasting industry.

(?) MFN: Mr. Enger, thank you for taking the time for this interview with MFN. Could you tell our readers a little more about yourself?

(!) T. E.: I’d be happy to … but first, you can call me Tom.

(?) MFN: We can do that … Tom.

(!) T. E.: As the Director of Product Safety at Clemco, my primary duty is to assure that all abrasive blasting products which Clemco manufactures meet or exceed U.S. federal, state, and local regulations, codes, and consensus standards. I also manage our Environmental Health and Safety Department. It assists our end users in understanding how to comply with environmental health and safety standards that apply to their businesses and also educates them on how to efficiently and safely use Clemco equipment. To this end, the department offers one-on-one assistance and training at international and national trade conferences, as well as offering training seminars at our headquarters. Clemco also publishes safety articles in associated trade journals, such as your magazine.

(?) MFN: Some of our readers may not be familiar with Clemco.

(!) T. E.: Clemco is the leading manufacturer of compressed-air-powered abrasive blasting equipment in the world. We build blast machines—with pressure vessels ranging from 0.5 cu ft to 160 cu ft; manual and automated blast cabinets—standard models, modified, or engineered; blast rooms—preassembled, predesigned, or engineered; and reclaim and dust collection systems. We even offer autonomous blasting robots.

We also offer countless accessories and—my favorite—personal, protective equipment: respirators, air pumps, blast suits and gloves, cooling comfort vests, cooling and heating systems for respirators, blast hose, remote control handles, couplings, nozzles, nozzles holders, and on and on. If your operation needs it, we have it or can build it.

Since the 1940s, Clemco has built industrial-grade blasting equipment for contractors, manufacturers, facility owners, metal fabricator, and other industries with surface preparation needs. Our machines are used to clean, deburr, deflash, shot peen, finish, remove corrosion, and otherwise improve metal and other surfaces. Our equipment can be found on every continent on the globe, except maybe Antarctica … but I wouldn’t entirely rule that out!

Clemco Industries markets its products in North and South America through a network of subsidiaries and independent distributors. Our sister company, Clemco International, coordinates manufacturing and distribution activities from its office in Germany to the rest of the world. This office houses engineering and sales operations and oversees manufacturing locations in Hungary and Denmark in addition to managing sales offices in Spain, Estonia, and Singapore.

(?) MFN: Sounds like Clemco has been steadily growing around the world for more than 70 years.

(!) T. E.: It has, and over those decades the industry has changed, particularly when it comes to safety.

(?) MFN: In what way?

(!) T. E.: In this interview, we couldn’t possibly cover all the safety considerations and standards involved in the design of abrasive blasting equipment and blast rooms. To mention just a few: crane and rigging standards, industrial ventilation, eye and face protection, signs and labelling, indoor air quality, protective headwear, respiratory protection, electrical standards, international building codes involved in construction and installation of blast rooms, standards for the spray and use of flammable materials, civilian and military requirements, explosive venting, ducting requirements, welding requirements, ladder safety, fall protection, confined spaces, masonry and concrete work, life safety, hazardous material management … you get the picture.

(?) MFN: Is there a topic that stands out that our readers should know more about?

(!) T. E.: Wetblasting, also known as vapor blasting and dustless blasting, is experiencing a resurgence in numerous industries. Unfortunately, wetblasting has many hazards that owners and operators of wetblast equipment may be unfamiliar with or unclear about. Most notably, current OSHA regulations still require that operators use NIOSH-approved, Type CE supplied-air respirators while wetblasting, unless an employer can prove that operator exposure is below permissible exposure limits (PELs).

(?) MFN: OSHA is the U.S. Occupational Safety and Health Administration. Why should our readers in the United States not be concerned with OSHA regulations?

(!) T. E.: The European Union, Pacific Rim countries, South American countries, Canada, and other nations have regulations that are almost identical to OSHA regulations. And Clemco Industries partners with Clemco International to assure that our products meet not only OSHA regulations, but the regulations of countries where our equipment is being used. It is important to understand that OSHA regulations are not the only design criteria for our equipment. There are a multitude of regulations, codes, and consensus standards that are used in the design of our equipment to enable the end user to efficiently and safely use it in an environmentally sound way, regardless of where in the world an end user is located.

(?) MFN: That is important. You were telling us about wetblasting and respirator use.

(!) T. E.: In August 2015, OSHA issued a letter of interpretation in response to Clemco’s request to clarify OSHA’s position on wetblasting and respirator use. Clemco had asked OSHA to respond to the following question: Is a Type CE continuous-flow respirator required when performing wet abrasive blasting where concentrations of toxic dust exceeds the permissible exposure limits (PELs) cited in 29 CFR 1910.1000?

OSHA’s response, in summary, was that NIOSH-approved, Type CE supplied-air respirators are required unless one of two conditions is met. One: exposure does not exceed PELs as measured by several methods outlined in OSHA’s response. Two: the blast operator is working in an exhaust-ventilated enclosure where the operator is separated from the nozzle and blast, such as a blast cabinet.
While wetblasting significantly reduces inhalation hazards, OSHA’s response to Clemco’s question, NIOSH testing, and other industry tests clearly indicate that wetblasting does not reliably reduce these hazards below the PELs at any level of abrasive use.  So unless employers can document that their wetblast operations meet OSHA’s standards, they need to protect their operators with NIOSH-approved, Type CE supplied-air respirators. A face shield and dust mask will not protect operators or comply with OSHA standards.

(?) MFN: Other than with wetblasting and respirators, where else are there misconceptions about safety issues?

(!) T. E.: There are numerous, but combustible dust fires and explosions come to mind. In 2008, OSHA and local building authorities began looking more closely at how to prevent combustible-dust fires and explosions. While design and performance standards did exist, a combustible-dust fire and explosion that year at the Imperial Sugar refinery in Georgia refocused attention on the issue. The incident killed 14 workers and injured 38.

Currently, some abrasive blasting operations fall under combustible-dust standards—but many do not. Understanding how these standards affect the design of abrasive blasting equipment enables customers to better manage their resources so that their facilities, and more importantly their employees, are protected from combustible-dust hazards.

The best way to comply with combustible-dust standards, is to have them not apply at all. Clemco can assist customers in determining if the dust from their abrasive blasting operations is noncombustible, in which case no further action is needed by them.

A Clemco regional sales representative can look at the combustibility of the media a customer plans to use. Based on tests Clemco has previously performed, Clemco may be able to simply tell customers whether their abrasive blasting operations produce combustible dust. If Clemco can’t give an answer based on these previous tests, a simple go/no-go test (pass/fail test), which is part of an ASTM E1226 test series, can be performed for $800.

If dust from a customer’s abrasive blasting process is combustible, Clemco’s on-staff product safety engineer can apply prescriptive and performance-design approaches to find a safe, cost-effective solution to ensure compliance and to protect employees and facilities. The recommendation will be based on approaches outlined in the primary reference document "NFPA 654: Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing, and Handling of Combustible Particulate Solids."

Before ordering and assembling equipment, ask Clemco to review the media to be used in the equipment. You will be pleasantly surprised by the cost-effectiveness of our solutions that protect facilities, and employees, from the hazards of combustible dust.

(?) MFN: Many of our readers operate blast rooms, so they might have concerns about combustible dust. Are there other current safety issues specifically regarding blast rooms they should be aware of?

(!) T. E.: Selecting the correct ventilation rate for a blast room can significantly impact operator exposure to inhalation hazards in excess of OSHA mandated PELs. Ventilation rates also impact visibility inside a blast room and selecting the correct dust collection system for a facility. Higher ventilation rates require more dust collectors, which increases the overall cost of the facility. For these and other reasons, determining a blast facility’s correct ventilation rate is critical when designing or selecting a blast room and its components.

The vast majority of abrasive blast rooms use crossdraft design, which ventilates air through a dust collection system without having to send it through a media reclaim system. Crossdraft rooms are significantly more cost-efficient than downdraft rooms.

Downdraft rooms are anomalies in abrasive blasting because they significantly increase the size and/or number of reclaim units needed. In a true downdraft room, all air enters from the ceiling and is reclaimed through the full floor.

A hierarchy of regulations and consensus standards mandate how to establish ventilation rates. However, OSHA regulations dictate using the document ANSI/AIHA Z9.4 ("Abrasive-Blasting Operations – Ventilation and Safe Practices for Fixed Location Enclosures") for determining ventilation rates.

When calculating ventilation rates, if the object being blasted does not extend the full length of the room then the air velocity is slower in the open areas in the front and back of the object than it is along the sides of the object. Slower air velocity exposes the operator to decreased visibility and increased inhalation hazards in the front and back of the room.

While it is true that velocity increases as it passes the object being blasted, velocity is slower in front of the object and behind it. Some manufacturers of blast rooms modify ventilation rates based on room changes (number of times the volume of air changes in a predetermined period of time; e.g., per minute). They then subtract the volume of the object being blasted from total volume of air in the room, in order to calculate a new ventilation rate. However, ANSI/AIHA Z9.4 addresses air speed through the entire room. Keeping the room changes the same, does not keep the air speed the same. Clemco recommends calculating ventilation rates based on an empty room to assure compliance with ANSI/AIHA Z9.4. It is the employer’s responsibility to comply with the OSHA regulations cited in this article. Deducting the volume of the object being blasted from the total volume of air in the room is tempting, but does not adhere to ANSI/AIHA Z9.4.

(?) MFN: Anything else you think our readers might want to know?

(!) T. E.: There is always more … but let’s save it for our next interview.

MFN would like to thank Tom Enger for this interview!

For Information:
Clemco Industries Corp.
One Cable Car Drive
Washington MO 63090, USA
Tel. +1.636 239-0300
E-mail: tenger@clemcoindustries.com

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