This report is part of the Safety Partners’ “Incidents, Accidents, and Near Misses” series. We are gathering information about incidents in laboratories and small-scale manufacturing operations from public and private sources in order to analyze and share lessons learned with the scientific and engineering community.
Last week, an explosion at a small-scale powder metallurgy manufacturing company in Woburn, MA, caused a fire and a serious injury to an employee. Local news reported that the employee was airlifted to Mass General Hospital with third degree burns over 90% of his body. What caused the explosion and fire? The information remains fragmented as OSHA and other investigators complete their analysis, but local news sources report the worker was removing titanium dust with a vacuum that was not properly grounded. The vacuum cleaner sparked, causing the titanium dust to explode.
What are some lessons learned? First, let’s understand the chemistry. Titanium is a beautiful material, both lightweight and strong, but the dust can be dangerous. Titanium is used in applications where both high strength and low weight are required, such as, aerospace components, high performance auto racing parts, surgical equipment, and joint replacements. But, titanium is pyrophoric: a cloud of titanium dust can ignite with explosive force sometimes spontaneously when exposed to air or when ignited by a spark. It doesn’t take much. The lower explosive limit for titanium dust is 20 to 30 micrograms per cubic centimeter. This is about the equivalent of 25 to 40 specks of household dust in a little box 0.4 inches on each side. In some cases, a static discharge of only 25 millijoules may cause ignition. This is about the same amount of energy you get from the static electricity created after you shuffle across a carpet and touch a light switch.
What steps can you take to prevent a titanium dust explosion? According to the International Titanium Association, the number one practice to prevent titanium incidents is good housekeeping. If you have titanium and titanium powder in your lab or your operation, you must make sure you have Standard Operating Procedures to cover both titanium and titanium powder, and that anyone who will be handling titanium understands those procedures. As a best practice, your laboratory leadership and executive leadership (CEO, COO, CSO, etc.) should understand and communicate the SOP, safe handling procedures, and the dangers associated with the poor handling of titanium powder.
Sources:
Journal of The Minerals, Metals, and Materials Society, 52 (5) (2000), pp. 13-17
www.titanium.org
www.periodictable.com