Safe Handling

Disposing of your scrap acetylene cylinders

Safe handling procedures for acetylene cylinders shouldn’t end when the cylinder runs out of gas. If that cylinder fails requalification, choosing the right disposal method can be just as important as choosing the right valve. Scrap acetylene cylinders are unique in their composition and have to be handled with the same care as when they were in service.

Unlike most compressed gas cylinders, acetylene cylinders are not entirely hollow. Within their steel exterior is a porous mass that contains dissolved acetylene gas. Since acetylene is so volatile, it must be stabilized with a solvent. In most cases, that solvent is acetone. Acetone is a volatile organic compound (VOC), and according to the National Institutes of Health, breathing moderate to high levels of acetone for short periods of time can cause nose, throat, lung and eye irritation. It can also cause intoxication, headaches, fatigue, stupor, light-headedness, dizziness, confusion, increased pulse rate, nausea, vomiting and shortening of a woman’s menstrual cycle.

Since acetone is still present within the core of the cylinder even after the acetylene gas has been used, it is important to consider the solvent when deciding the right disposal method for your company.

The two most popular methods of disposal have traditionally been landfilling and stockpiling. Each has its benefits, but both carry potentially serious long-term liability concerns.

Landfilling is an inexpensive and quick way to rid your facility of scrap cylinders. Most landfills charge a flat rate per pound or ton, making the size of the cylinder irrelevant when calculating the price of disposal. For companies struggling to find the budget to dispose of their cylinders, this option tends to prove the least expensive. However, it can also be one of the riskiest. When a cylinder is buried in a landfill, any potential liability resulting from its contents rests with the previous cylinder owner. Human exposure to acetone can occur via contaminated drinking water or food and by living near a landfill site or other facility that releases acetone emissions.

Some landfills have begun refusing acetylene cylinders specifically for this reason. Others require that all cylinders go through some sort of solvent recovery process to remove the acetone prior to disposal, similar to the process required in the European Union. Acetylene tanks produced before 1984 may pose an even more serious disposal challenge for tank owners. In these older tanks, the solvent-bearing mass housed in the tank often incorporates small amounts of asbestos, employed to add stability without flammability. While these asbestos fibers pose no harm during the discharge of the acetylene in the tank, they do represent a disposal concern. Asbestos-free tanks became the norm in the 1990s, but many older tanks are still in use or are stockpiled awaiting disposition.

Stockpiling acetylene cylinders is a great short-term solution for smaller distributors who may only have a couple of scrap cylinders at a time. It is also a great way to consolidate your scraps until you acquire a large enough quantity to explore more cost-effective disposal options. However, stockpiling is a short-term solution. Unless your facility is large enough to house thousands of scraps, or the EPA doesn’t know you exist, eventually you will have to find an outlet for your cylinders. Even in the short term, stockpiling exposes your employees, customers and neighbors to the same potential health risks as landfilling.

In addition to housing and safety concerns, stockpiling cylinders can actually increase your disposal expenses. As one distributor put it, “The longer you wait, the more cylinders you will wind up with. So instead of disposing of 50 cylinders, you’re looking at 1,000. Plus, as fuel costs increase, so will the cost of disposal.”

Borrowing from the European model, which requires a minimum removal of the solvent before landfilling, some companies are now sending their scrap cylinders to specialty recycling companies for disposal. The recycling process does not position the cylinder for reuse, but rather removes and salvages any usable material from the cylinder.

In most cases, the first step is to remove the acetone solvent from the core of the cylinder. The acetone, which is in liquid form, can be removed by heating the cylinder until the acetone becomes a gas. Once extracted by a vacuum, the gas can be cooled back into a liquid state for reuse. With the solvent removed, any potential liability associated with the chemical is removed. The steel shell of the cylinder can then be cut, and the solid core can be removed. The steel shell can be sent to steel recyclers as scrap. The solid core of the cylinder, which is a lime-silica compound, can be sent to a sub-title D landfill.

Recycling not only eliminates liability, it also illustrates your company’s commitment to the environment and your community. Sustainability measures, including recycling and pursuit of ISO 14001:2004 certification, are valuable tools that can be used to the benefit of the business. To internal stakeholders, they demonstrate control over organizational processes and activities that impact the environment and assure employees or potential employees that they are working for an environmentally responsible organization.

While recycling is becoming more popular, the average cost per cylinder for disposal is often slightly more than for landfilling. More importantly, since there are only a small number of facilities designed for solvent recovery, and even less for full recycling, transportation costs can be a tough pill to swallow. For companies struggling to find the budget to dispose of their cylinders, recycling often seems out of reach.

In an economy like this, choosing the right method of disposal can make a world of difference. It is important to consider all factors when choosing the right option for your company, including your current budget and the long-term effects of your decision. There is no “right” method of disposal, and, for some, a combination of all three methods listed above may make the most sense. Be sure to select the most safe and effective method for your needs.

Gases and Welding Distributors Association
Meet the Author
Erik Cannon is assistant marketing director at Cylinder Recyclers, located in Rockport, Massachusetts, and on the Web at