Considerations for PPE in Melting & Pouring for Foundries
Click here to see this story as it appears in the November 2017 issue of Modern Casting
Note: This article is an excerpt from The Fourth Edition of the PPE Guide on Metalcasting Operations (2015), compiled by the AFS Safety & Health Committee, and edited by Sue Thomas.
In safety and health practice, the hierarchy of controls specifies elimination of the hazard. Other control strategies such as substitution, engineering controls, work practices, and administrative controls should also be considered. Personal protective equipment (PPE) is often at the bottom of the hierarchy due to issues associated with comfort, fit, acceptability, reliability and effectiveness. In fact, reliability and performance issues are also associated with engineering controls. In situations where exposures are generally controlled, PPE is often used for the following reasons:
As a backup precaution in case other controls fail.
In situations where exposure variability means occasional overexposures are possible; or as additional protection to reduce exposures to below the levels possible with other controls.
While higher level controls are implemented.
While waiting for test verification.
To augment other controls.
PPE requirements are based on a hazard assessment as required by OSHA Standard 29CFR 1910.132. Each job and related work activity should be evaluated. The hazard assessment should be reviewed when job hazards change and should be modified as necessary. And it should be documented and reviewed annually with employees.
Employees who are required to wear PPE or specialized clothing should be trained in its limitations, proper inspection, use, care and storage. An employee must be retrained when:
Work habits or demonstrated knowledge indicates a lack of the necessary understanding, motivation, and skills required to use the PPE (i.e., improper usage of PPE).
Workplace changes require updated training (i.e., when employees change jobs or new equipment is introduced), or PPE updates require more advanced training.
Periodic refresher training.
PPE must be correctly fitted, worn, maintained, cleaned and disposed of properly. In situations where contaminated clothing or equipment may pose a risk to individuals other than the user (i.e., laundry or cleaning personnel) they should be provided with appropriate hazard warning information.
Wearing jewelry, including exposed body piercing jewelry, should be prohibited in hazard zones. Clothing should be properly sized so as not to get caught in moving machinery. Hair longer than four inches can be drawn into machine parts such as suction devices, blowers, chains, belts, and rotating devices. Hair must be securely restrained with a bandana, hair net, soft cap or pulled back.
Protective clothing may add to the heat load of the worker and increase body temperature. A heat stress program may be necessary to manage the potential heat stress hazard.
Fall protection may be necessary for work activities performed at heights above four feet without adequate railings, guards, or near pits or open-sided floors. It should be considered for activities such as cleaning or clearing jams, or accessing equipment.
Clothing and PPE: Melting and Pouring Operations
Secondary protection is defined as clothing or personal protective equipment designed as basic protection for continuous use in areas where intermittent exposure to hazards is possible. Recommended minimum specialized clothing and personal protective equipment (PPE) for all melting and pouring operations include the following secondary (basic) protection:
100% cotton or wool socks.
100% cotton undergarments.
100% cotton or wool outer garments.
Safety glasses with side protection.
Leather safety shoes with toe protection and a smooth toe.
Hearing and respiratory protection may be necessary depending on the degree of potential exposure. For employees in a hazard zone (i.e., near a furnace or ladle containing molten metal or other known hazards) additional primary protection is required.
Primary protection is defined as clothing or personal protective equipment (PPE) designed for activities where significant exposure to hazards such as molten metal splash, radiant heat, flame, noise or flying particles is likely to occur.
Considerations for Hazard Assessment
When doing a thorough hazard assessment, regardless of whether a foundry is pouring ferrous or nonferrous metals, it must consider the following:
Presence of molten metal in furnace, ladle and/or mold.
Temperature of the metal or hot surface.
The level of the metal and area of the body that could be impacted by a splash, runout, sparks, flames, or hot surfaces.
Proximity to molten metal and hot surfaces (i.e., work inside hazard zone around induction furnaces).
Material being handled (i.e., additives, chilling blocks).
Amount of metal which will affect the amount of radiant heat and quantity of metal, melted or poured, that could impact the body.
Potential for molten metal explosion due to moisture in charge materials, failure of furnace cooling lines, or bursting molds.
Further Recommendations and Comments
The following are more recommendations and comments for the proper usage of clothing to adhere to PPE requirements.
Reference OSHA Standard 29 CFR 1910.132 for General PPE requirements.
Refer to ASTM Standard F 1002 Standard Performance Specification for Protective Clothing for Use by Workers Exposed to Specific Molten Substances and Related Thermal Hazards and request to see the results of the ASTM Standard F 955 Standard Test Method for Evaluating Heat Transfer for specific fabrics.
ASTM Standard F 955 Standard Test Method for Evaluating Heat Transfer tests are conducted using pure metals and results may be different with various alloys. Users should use test data from their own alloys to compare fabric performance. Combinations of primary and secondary clothing/protective garments used at a facility should be tested to ensure that the combination performs satisfactorily using the Stoll curve test.
For molten metal splash hazards, clothing may be rated for levels of protection according to ISO 9185 (D1, D2, or D3 for aluminum; E1, E2 or E3 for ferrous metals.
Wear pants or leggings that cover the top of the boot (and spats, if worn) to prevent molten metal and sparks from entering the boot. Never tuck pant legs inside the boot or spats. If leggings are worn over pants a long protective coat must be worn which covers the top portion of the legging.
If laced boots are worn, spats or leggings that cover the lacings must be used whenever molten metal or sparks could lodge in the tongue area of the boot.
Nonferrous Metals—Do not wear phosphorus treated cotton because molten metal tends to stick to the fabric. Many flame resistant (FR) cotton fabrics use a phosphorous-based treatment.
Do not wear polyester, nylon, and other man-made materials that can melt and readily ignite.
Long pants are required and long-sleeved shirts are recommended.
For pouring operations the use of spats, leggings, and chaps should be evaluated.
Wear clothing that does not trap molten metal and sparks (i.e., no cuffs, open pockets, loose legging tops, etc.).
Maintain all protective clothing in serviceable condition. No holes, rips or tears. Refer to ASTM Standard F 1449 Standard Guide for Industrial Laundering of Flame, Thermal and Arc Resistant Clothing.
Fabric repair must be done in a way that maintains the flame-resistant properties.
Wear types of PPE in any combination as needed to protect body parts that are exposed to heat or metal splatter as determined by the hazard assessment for each work activity.
Protective clothing may add to the heat load of the worker. Recognize the potential for heat stress when selecting special clothing. A heat stress program may be necessary to manage the potential of heat stress.
Aluminized PPE should be considered for exposure to high heat and spark producing areas such as lancing, tapping, slagging or activities where molten metal splash is possible. It is not universally required when pouring metal into molds.