Corrosion commotion

Written by  Linda Johnson 23 January 2015
At Calgary-based Canexus, which manufactures corrosive chemicals including sodium hydroxide and hydrochloric acid, no one gets into the plant without proper personal protective equipment (PPE).

“That’s step 1. Corrosives, especially sodium hydroxide, can burn the skin,” says Jennifer Lewis, manager of quality and Responsible Care, an industry wide initiative to promote environmental, health and safety performance. “But it can be very subtle, as well, because it feels like soap.”

Corrosives are materials that can attack and chemically destroy exposed body tissues. They begin to cause damage as soon as they touch the skin, eyes, respiratory tract and digestive tract.

“It’s where there has been corrosion of the tissue, not just irritation. Corrosion kills living cells,” says Warren Fox, an instructor in the occupational health and safety program at the British Columbia Institute of Technology (BCIT) in Burnaby, B.C. “With many of the chemicals we work with, it’s a matter of concentration: In low concentration they can be an irritant to the skin or eyes, but in a stronger concentration they cause enough damage to the skin or eyes that we end up with a scar.”

Corrosive materials are present in almost every workplace, and everyone who works with corrosives must be aware of their hazards and how to work safely with them.

“You’re never going to find an industrial site that doesn’t have a corrosive in it somewhere,” says Darcy Carriveau, Responsible Care co-ordinator at Vancouver-based Methanex. “Even lubricants are significant corrosives often because of their cleaning properties.”

Most corrosives are either acids or bases. Common acids include hydrochloric acid, sulfuric acid, nitric acid, chromic acid, acetic acid and hydrofluoric acid. Common bases are ammonium hydroxide, potassium hydroxide (caustic potash) and sodium hydroxide (caustic soda), according to the Canadian Centre for Occupational Health and Safety.

For occupational health and safety professionals, Fox adds, another concern is whether a chemical will corrode other materials, particularly metal.

“A material that is subject to a corrosive and fails during operation can present a safety hazard, not just a hazard to health,” he says.

Take stock

The first step to working safely with corrosive chemicals is conducting an inventory of all such materials on-site, says Ilma Bhunnoo, occupational hygiene specialist with Workplace Safety and Prevention Services (WSPS) in Mississauga, Ont. The inventory should identify:

• chemical types
• physical state (solid or liquid)
• toxicity
• material temperature
• storage location.

The risk assessment should also examine handling processes, she says. This covers such information as amounts used, whether exposure is continuous or intermittent and whether workers are exposed through contact, inhalation or ingestion. It’s also important to evaluate both long- and short-term exposures.

A worker may, for example, be required to stand beside an electroplating tank filled with a diluted acid and be performing a dipping process for an entire shift. Here, she says, you must consider the eight-hour exposure.

“Another worker, however, may have to pour the concentrated solution into a mixture. It may take only 15 minutes to do, but exposure during those 15 minutes may be very high,” says Bhunnoo.

In assessing possible consequences of an incident, employers should consider corrosives from three perspectives: health effects (which range from first-aid injuries to critical injury or fatality); chemical reactivity (some chemicals are incompatible) and flammability (some cause explosions or fires).

To implement hazard controls, substitution is the obvious first step, says Fox. However, where highly corrosive materials can be replaced by less corrosive ones, most employers have done so, he adds.

“I think, in 2014, we’re left with a group of chemicals in the workplace where we will have to deal with their reality.”

There are thus two major controls for most companies: safe work procedures and PPE.  

Implement safe work procedures

Good procedures will be determined by the nature of the job but, generally, these should be designed to limit exposure to skin and eyes.

Where large containers of corrosives are handled, they can be replaced by smaller ones. They may also be placed in holders so, if accidently dropped or damaged, they won’t break apart. Lids should fit securely, and the chemical should not be unnecessarily exposed and able to spill easily.

“Nothing high tech,” Fox says. “These are just: How are we going to make sure, when we’re handling these materials, we don’t increase the possibility they are going to splash out onto our skin or eyes?”

Employers must make sure employees are properly trained to work with corrosive products.

Training at Canexus is developed according to the tasks the employee or contractor is going to perform. It’s important to ensure workers understand the training.

“People learn in different ways: some are more visual, some are more auditory,” says Lewis. “So having some demonstration of comprehension and competency once the training is complete — in whatever format it’s being presented in — is really key.”

Another aspect of training is ensuring workers understand how to read product labels and interpret corrosion pictograms on containers.

Companies must also have the material safety data sheet (MSDS) for each hazardous chemical they have on-site. These provide information on the product’s physical and chemical properties, hazards and controls, such as safe usage, storage, disposal, appropriate PPE and emergency procedures.

“Employers dealing with a chemical that can burn skin must have emergency procedures in place in case someone gets the chemical on their skin, and workers need to know those procedures. Or in case a worker gets the chemical in an eye, they must know how to use the eyewash station,” says Lauren Welsh, spokesperson for Alberta’s Occupational Health and Safety department.

Carriveau says Methanex, which manufactures methanol and uses a range of corrosives in the process, has a chemical management system in place that follows a product from its entry onto the site all the way through to recycling or toxic waste disposal.

“So, you start with the warehousing system, when it’s brought into the site. That way, it’s catalogued and appropriately stored, the appropriate safety data sheet is with it and anyone who’s going to handle it receives education from the safety data sheet in tool box meetings or in more formal processes.” 

Match PPE to corrosive substance

Selection of PPE is based on CSA Standard Z94.3, Eye and Face Protectors, as well as knowledge of the tasks, Fox says. Goggles should be chemical-splash resistant. With some kinds of work, the face as well as the eyes should be covered, and workers will need a chemical-splash goggle with a full-face shield to protect all the skin on the face.

Depending on the job, he adds, employers may need to provide long-sleeved gloves or both full-sleeved gloves and full aprons. Glove and clothing material must be selected to match the corrosive substance. Most glove manufacturers have tested their glove materials for their ability to resist a variety of chemicals.

“There are six or eight materials out there that are better at resisting corrosives than others,” Fox says. “We use standard selection charts to choose not only the right length of glove but also the right material. But it’s definitely situation specific.”

In Canada, the standard most commonly followed for emergency washing facilities is ANSI Z358.1. Compliant equipment includes features such as an easy-activate valve and the ability to reach appropriate temperature (tepid) and full volume instantly. Risk assessment requirements are set by the provinces. These usually involve what chemicals are used; how much is used; and where and under what circumstances they’re used.

“We end up in most cases with a fairly simple risk assessment scenario: we say it’s moderate, low or high risk,” Fox says.

According to the ANSI standard, emergency washing facilities must be accessible within 10 seconds.

“It’s great to have an emergency shower. But imagine having just had your eyes drenched with a chemical and you’re trying to find an emergency shower on another floor. That’s not going to work,” he says. “So the question is: Have we set up enough facilities in the right places with no barriers so that even if a worker had to find her own way there, with her eyes stinging, she’s going to be able to do that?”

While companies have to install and maintain proper emergency washing facilities, these facilities are not getting much use these days, Fox says.

“Based on the audits I do, I think employers who run a good OHS program are also doing a fantastic job,” he says. “The potential for a lot of chemical injuries is there, but I don’t think we’re seeing a lot of them because there’s a lot of good safety been done around them.”

Linda Johnson is a freelance writer based in Toronto. She can be reached at

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