AWS F3.2:2018 pdf download

AWS F3.2:2018 pdf download.Ventilation Guide for Weld Fume
1. Introduction, Scope, and General Provisions
1.1 Introduction. A ventilation system consists of either a naturally, or mechanically, supplied and exhausted flow of air which can be used to control fumes and gases generated during welding or cutting operations. Mechanical ventilation systems are typically more consistent in their ability to control contaminants and are generally utilized when it is neces- sary to: (1) Control contaminants to meet occupational exposure limits (PEL, TLV, etc.); (2) Advance environmental stewardship by collecting emissions at the source, for disposal and recycle; and (3) Improve housekeeping by reducing settled particulates. 1.2 Scope. This guide describes recommended principles of ventilation to be used in facilities where welding and allied processes are performed. The primary objective of this document is to enhance the health and safety of all those found in a welding environment. Other objectives include the provision of information relevant to energy conservation and envi- ronmental compliance. This guide does not provide information on respiratory protection or specific precautions related to working in a confined space. Also, this guide does not address issues associated with combustible dust hazards appli- cable to ventilation systems. Information dealing with this issue can be found in NFPA 654, Standard for Prevention of Fire and Dust Explosions from the Manufacturing, Processing and Handling of Combustible Particulate Solids, and NFPA 484, Standard for Combustible Metals. Basic information related to a range of ventilation systems and techniques that can be used in a welding and cutting envi- ronment is provided here. Comparisons are drawn between techniques and highlight both the effectiveness and relative cost of each approach. It is intended that this information will assist in the identification and selection of an appropriate ventilation solution for a specific welding and/or cutting operation.1.3 Units of Measure. This standard makes sole use of U.S. Customary Units. Approximate mathematical equivalents in the International System of Units (SI) are provided for comparison in parentheses or in appropriate columns in tables and figures. 1.4 Safety. Safety and health issues and concerns are beyond the scope of this standard; some safety and health informa- tion is provided, but such issues are not fully addressed herein. Sources of safety and health information include: American Welding Society: (1) ANSI Z49.1, Safety in Welding, Cutting, and Allied Processes (2) AWS Safety and Health Fact Sheets (3) Other safety and health information on the AWS website Material or Equipment Manufacturers: (1) Safety Data Sheets (SDS) supplied by materials manufacturers (2) Operating Manuals supplied by equipment manufacturers Applicable regulatory agencies, such as: (1) Occupational Safety and Health Administration (2) Environmental Protection Agency
4. Occupational Exposure Limits
The need to prevent unacceptable airborne contaminant exposures in the workplace environment is most often the impe- tus behind the deployment of ventilation systems. Ultimately, it is likely that the effectiveness of those ventilation sys- tems will be judged more by the extent to which airborne contaminant exposures are maintained or controlled to levels below specific occupational exposure limits than by their ability to meet targeted system performance characteristics. Regulations related to contaminant and other exposures in the workplace tend to be performance based and compliance is determined by taking measurements of employee exposure levels and comparing them to occupational exposure lim- its. Therefore, it is crucial that those involved in decisions related to the selection or application of ventilation systems understand the fundamental concepts related to occupational exposure limits. 4.1 Permissible Exposure Limits. Permissible Exposure Limits (PELs) are regulatory values in the U.S. and are pub- lished by the Occupational Safety and Health Administration (OSHA). PELs are enforceable to protect workers against the potential health effects of overexposure to hazardous substances. PELs are regulatory limits on the amount or con- centration of a substance in the air, expressed in terms of an averaged 8-hour exposure period or 8-Hour Time-Weighted Average (TWA). OSHA also designates compounds requiring engineering and other controls to prevent skin exposures. PELs can be found in 29 CFR 1910.1000, Tables Z-1, Z-2, and Z-3, and references within. Some states have their own occupational safety and health programs, so state exposure limits may differ, but they must be at least as stringent as the federal OSHA limits. OSHA has established other types of exposure limits. The Short Term Exposure Limit (STEL) is expressed in terms of a concentration averaged over a 15-minute interval.