Everyone contributes to a $afe workplace!
A question arose in a recent Law Seminar concerning possible unsafe exposure for Quality Control Technicians while they are "pulling samples" from moving belts. The employees themselves were concerned about the cost of "engineering out" until they were acquainted with injury costs during the class. They contacted their Safety Department. The Techs, Safety Officer, and the Site Management met and discussed the exposure. The recommendations they arrived at will lessen exposure to the Hazards of the process and allow production to continue efficiently as to process and cost. Here are the evaluations and recommendations at which they arrived . Please note that though these improvements will take a reasonable 30-60 days to implement, safe procedures have been adopted for the interim period. Many thanks to Hanson for sharing this with the Industry.
Hanson Aggregates Pacific Southwest Region
QC Sampling Procedures – Safe Access Project
Problem: In many instances, QC personnel are required to take samples from various locations throughout our plants that may expose them to moving machine parts and/or may present physical stresses which can be either eliminated or reduced through simple engineering and/or safe work practices.
Below are several examples of the areas and locations within our plants which may present these hazards and solutions that may reduce the potential for injuries.
Samples are often taken alongside conveyor belts. In some instances the conveyors are elevated making it difficult for QC techs to safely reach the belt and the material contained thereon. Currently, the practice is to de-energize the conveyor and step onto the conveyor framework to access the material to be sampled.
By installing simple access steps that may be attached and hinged to the conveyor framework, these steps may be swung down for use and then swung up and pinned out of the way.
The steps may be easily constructed from angle iron and expanded metal to withstand exposure to the mining environment.
The steps should be constructed to meet the conditions present at the sampling location (angle of walkway, proper height, etc.) and generally do not need to be more than 2 steps high.
Alternatively, lightweight portable steps may be carried by the QC tech to the subject site, but in most cases, the angle of the walkway and the height of the conveyor will necessitate the construction of custom steps.
In some instances, access to lower conveyors may be done from existing structures, blocks, foundations and other similar places. However, simple catwalks, platforms and other devices may need to be constructed to permit safe access to the conveyor belts.
In the example shown here, a 3-4 foot catwalk could be constructed to reduce fall hazards while accessing the conveyor belt. Proper handrails and other required safety features would need to be installed on any catwalk built for this location.
As mentioned above, the conveyor needs to be de-energized prior to taking the necessary sample.
A common practice is to take samples from head pulley sections and/or feeder bins. It was observed that the existing hatches which allow access to the flow of material presents exposure to moving parts when QC personnel open the hatch and take the sample with a shovel.
In addition, some open hatches are prone to close due to improper angles and equipment vibration.
Using sampling procedures used at hot mix asphalt plants as a model, simple access ports can be constructed in the feeder bins. The ports may be fitted with sliding doors to prevent material spills when not in use.
A sampling scoop may be constructed to fit within the port and which has been fitted with "stops" to prevent the scoop from traveling too close to the moving machine parts but still permitting the scoop to catch the flow of material.
Because the distance between the edge of the feeder bin and the moving machine parts may vary from conveyor to conveyor, it is important that scoops are carefully matched to fit the conditions at each conveyor.
This may require the scoops to be secured with lightweight chain at each sampling port and/or matched with identifying marks or numbers.
Other items for discussion:
Sampling from material piles, including surge piles by climbing the sides of the stacked material should be ceased immediately. Climbing the sides of the piles presents inundation hazards, walking/climbing over bridged material and falling into surge pile draw points.
It was indicated that it is preferred that samples are not taken on stacked material due to concerns for reliable, representative samples but that it is often necessary at portable plants and at locations where no other access exists.
In these instances, QC personnel should request the assistance of front-end loader operators to gather the material to be sampled with their loader buckets. The material is taken from the pile by the loader, the bucket is lowered to the ground, the QC tech grabs some material for sampling and the remaining material is returned to the pile. This may be repeated as often as necessary to retrieve reliable samples from each pile. It was further indicated that two-way radio communication with loader operators is available which can make the process more efficient.
Currently, the QC Department is identifying all sampling locations at each plant and creating safe sampling procedures at each location. This document can be used by operation personnel to assist the QC Department to construct proper sampling devices, ports, access steps and other similar devices. In addition, this document may be used for training and re-training of QC personnel in safe work procedures.
Alternative solutions and suggestions are highly encouraged. Certainly, the suggestions proposed here may not be workable in all locations, but it is important that all workers and work procedures conducted on our sites provide the highest measure of safety possible.
This project should be considered a high priority since sampling is conducted frequently at all plants. A due date on completion of this project is suggested to be by mid-August. It is also suggested that a qualified person within the QC Department heads this project until completion. The Safety Department is more than able to provide any assistance necessary to see the project to the end.
If you have any questions or comments regarding this matter, please do not hesitate to contact me.
Terry L. Tyson
Regional Director of Safety
Hanson Aggregates Pacific Southwest Region