Increasingly strict fume regulations and recommendations, like those set forth by agencies such as the Occupational Safety and Health Administration (OSHA), enforce employee exposure limits for each individual metal, metal oxide or gas found in the weld plume, such as manganese and hexavalent chromium.
Beyond safety concerns, proper management of the weld fume created by the welding process also can help improve productivity and quality.
There are numerous ways companies can manage weld fume management — from implementing a welding process change or new filler metal to the use of personal protective equipment (PPE). This article discusses some frequently asked questions regarding effective weld fume management with regard to fume extraction systems and respirators, in particular.
Please note: It is important to consult with an industrial hygienist for weld fume management recommendations for a given application and welding operation. Also remember, employee training is critical to the successful execution of these controls and other weld fume management activities.
Q: What are the options recommended by OSHA for minimizing weld fume exposure?
The agency’s Hierarchy of Controls provides the steps for employers to take in order to comply with environmental regulations and improve welding operator safety. Note that every welding environment is different and therefore should be evaluated by a qualified industrial hygienist to determine the appropriate course of action for fume controls. It is also important to conduct air sampling to better understand the types and levels of contaminants in the welding environment.
OSHA’s Hierarchy of Controls recommends minimizing weld fume exposure through a sequence of steps:
- Elimination or Substitution, such as using low-manganese filler metals or changing the shielding gas.
- Engineering Controls, such as centralized ventilation or fume extraction equipment.
- Administrative Controls, such as proper body positioning.
- Personal protective equipment (PPE), which includes respiratory protection.
Please note: The examples within each of the above steps are not inclusive; there are many other activities associated with each step.
Q: How can following proper welding procedures and using proper body positioning help mitigate fume exposure?
Placing more filler metal into the weld joint than is necessary — overwelding — can result in greater fume generation. Following proper welding procedures can minimize the risk of this occurrence, while also helping ensure the best weld quality.
Proper body position helps minimize the risk of the welding operator’s face penetrating the weld plume and having the weld fume enter the breathing zone. When possible, welding operators should position themselves away from the weld (not directly over it) and avoid standing in between a fan and the weld.
Avoiding a position between the weld and the fume extraction arm also helps prevent blocking the suctioning capabilities of the fume extraction arm, allowing it to work more efficiently.
Limiting cross ventilation in the welding area also helps minimize interference with the capture of the fume, lessening the opportunity for the fume to be blown back at the welding operator’s face or at other workers nearby. Welding operators should position themselves so that the airflow is moving from their back to their front. Using partitions or curtains in the welding enclosure can also help control cross ventilation.
Q: What type of fume extraction system is ideal for welding applications?
Source capture is the preferred method of weld fume extraction because it captures and removes contaminants at their source before they reach a welding operator’s breathing zone.
Fume extraction systems are available in different shapes and sizes, and are rated based on the amount of cubic feet of air they extract each minute (cubic feet per minute, or cfm). Cfm should be tested at the hood for the truest rating.
Systems are divided between low-vacuum/high-volume solutions and high-vacuum/low-volume solutions. Low-vacuum/high-volume systems process a larger volume of air but at generally lower vacuum pressures. These systems offer larger capture zones. Conversely, high-vacuum/low-volume systems capture weld fume much closer to the weld, via a smaller attachment such as a nozzle.
When selecting a fume extraction system, consider the available space in the weld cell and make sure the capture velocity is sufficient to pull the fume away from the welding operator’s breathing zone.
Q: What is the proper positioning of a fume extraction arm?
For the best results, a moveable hood or fume extraction arm should be positioned above the arc, at approximately a 45-degree angle. A hood distance of 1 1/2 duct diameters away is generally recommended, though the distance will vary based on the velocity and the volume of air being captured.
In the past, there may have been significant downtime during welding so welding operators could pause to reposition or adjust the fume extraction arm. The availability of newer fume extraction systems that create a negative pressure zone help address that problem, by increasing the distance they can capture fume — up to 5 feet away and an area up to 3 feet wide.
Q: When should respiratory protection be incorporated to manage weld fume levels?
According to OSHA, respiratory protection should be implemented in cases where engineering controls are not feasible, or when engineering controls alone do not reduce hazard levels below Permissible Exposure Limits (PEL).
Manufacturers offer a wide variety of respirator options, including dust masks, half masks, supplied air solutions and powered air purifying respirators (PAPRs). OSHA has identified two major types of respirators: air-purifying and atmosphere-supplying. Air-purifying respirators have filters or cartridges and remove contaminants from the air by filtering them prior to reaching the welding operator. Atmosphere-supplying respirators provide clean air from an uncontaminated source. An assigned protection factor (APF) rating denotes the workplace level of protection that each respirator is expected to provide.
A calculation called maximum use concentration (MUC) can help determine the proper respiratory solution for an application. Multiplying the respirator’s APF by the required OSHA permissible exposure limit, short-term exposure limit or ceiling limit determines the MUC. OSHA considers the MUC to be the upper limit at which the class of respirator is expected to provide protection. Whenever exposures approach the MUC, companies should select the next higher class of respirators to provide optimal protection for employees.
Proper fitting is key with some types of respirators, such as half masks, so be mindful that fit tests may be required to ensure a proper seal.
Q: What are the documentation and inspection rules for respirators?
Respirator inspection is an important step that can help ensure the welding operator is fully protected. Train employees on proper inspection procedures before any kind of respirator is used. This information can be found in a respirator’s user instructions.
Employee training also should cover topics including proper selection of respirators; the consequences of improper fit, usage or maintenance; proper maintenance and storage procedures; and how to use respirators in emergency situations.
Having proper documentation when respirators are used also is a critical part of maintaining OSHA compliance. Requirements vary between mandatory and voluntary respirator use, though both do require a written respiratory protection program. The written program must include information such as respirator selection; medical evaluations; fit testing for tight-fitting respirators; use in routine and emergency situations; established schedules for cleaning; procedures to ensure air quality and flow for atmosphere-supplying respirators; employee training; and evaluation of the respiratory program.
Q: How important is proper storage and maintenance of fume extraction systems and respirators?
Whether the chosen method is a fume extraction system or a respirator, proper maintenance and storage (in the case of respirators) is an important part of saving time and money, and ensuring the equipment is working to its fullest capacity to help create a safer environment.
Filter replacement and maintenance is a key part of fume extraction systems, which are available with disposable filters or with self-cleaning filters. Less air passes through a dirty filter, which reduces the amount of airflow at the hood for effective fume collection. Systems often have a gauge to indicate when a disposable filter should be changed. For self-cleaning systems, choosing the appropriate filter type can help optimize fume collection. Also, make sure the compressed air line is in use and working properly, and that the air is clean and dry.
When using a respirator, proper storage — and cleaning and replacing the units — is important. The written respiratory program requires a filter change schedule. Respirator filters must be replaced, as they cannot be cleaned, unlike other fume extraction products.
Making the fume abatement decision
Implementing the necessary process changes and technologies that reduce weld fume can lead to greater productivity, better weld quality, and a safer, compliant environment for employees. These steps also can help extend equipment life and help companies comply with federal regulations.
When it comes to weld fume management, there are numerous solutions available, each with their own benefits and considerations. To help make the decision, consult with an industrial hygienist or other licensed safety professional, trusted welding distributor or fume management solutions manufacturer.