Beyond compliance concerns, proper management of 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 best practice to consult with an industrial hygienist for weld fume management recommendations for a given application and welding operation to help ensure the proper controls are put into place. Also remember, employee training is critical to the successful execution of these controls and other weld fume management activities.
How can following proper welding procedures and using proper body positioning help mitigate weld fume exposure?Following proper welding procedures can minimize the chance that too much filler metal is being placed into the weld joint than necessary (overwelding), which can result in greater fum generation and lead to poor weld quality.
Operators should position themselves away from the weld so that their face is not penetrating the weld plume. They should avoid standing between the weld and fume extraction arm, as this can prevent the extraction arm from working at full efficiency. Operators should also avoid standing in between a fan and the weld.
Limiting cross ventilation in the welding area can also help minimize interference with the fume capture. Welding operators should position themselves so that airflow is moving from their back to their front. Using partitions or curtains in the welding enclosure can also help control cross ventilation.
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. There are two types of systems available: Low-vacuum/High-volume and High-vacuum/Low-volume.
Fume extraction systems are available in different shapes and sizes, and are rated based on the amount of cubic feet of air they extract per minute (cubic feet per minute, or cfm). 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 fumes away from the welding operator’s breathing zone.
What is the difference between low-vacuum/high-volume and high-vacuum/low-volume extraction systems?
Low-vacuum/High-volume systems process a larger volume of air but at generally lower vacuum pressures. These systems offer larger capture zones.
High-vacuum/Low-volume systems capture weld fume much closer to the weld, via a smaller attachment such as a nozzle.
What is the proper positioning of a fume extraction arm?
For the best results, a movable 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 is generally recommended, though the distance will vary based on the velocity and volume of air being captured. Each system varies.
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, while they are being implemented, or when engineering controls alone do not reduce hazard levels below Permissible Exposure Limits (PEL).
What is the difference between air-purifying and atmosphere-supplying respirators?
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.
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.
What is an Assigned Protection Factor (APF)?
An Assigned Protection Factor (APF) rating denotes the workplace level of respiratory protection that a respirator or class of respirators is expected to provide to employees when the employer implements a continuing, effective respiratory protection program.
Learn more about APFs for OSHA's revised respiratory protection standard.
What are the documentation and inspection rules for respirators?
OSHA requires an employer to develop and implement a Written Respiratory Protection Program with required worksite-specific procedures and elements for both mandatory and voluntary respirator use. For employees voluntarily using respirators, employers must provide those users with a copy of Appendix D to OSHA 1910.134.
Respirator inspection is an important step that can help ensure the respirator is in proper working order. Employees should be trained on proper inspection procedures before any kind of respirator is used. This information can be found in a respirator’s user instructions.
Employee training should also 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.
How important is proper storage and maintenance of fume extraction systems and respirators?
Proper maintenance and storage is an important part of saving time and money, and ensuring your equipment is working to its fullest capacity to help create a clean and compliant environment.
Filter replacement and maintenance is key to the efficiency and longevity of fume extraction systems. Less air passes through a dirty filter, reducing the amount of airflow at the hood for effective fume capture. 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, cleaning and replacement of 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.