DVIDS – News – AEDC Model Shop reduces risk with new chemical cleaners

ARNOLD AIR FORCE BASE, Tenn. – Mission first, safety always.

Efforts to put this common saying into action in a meaningful and measurable way came to fruition this summer at Arnold Air Force Base.

After more than a year of research and preparation, two new citrus-based chemical cleaners were delivered and used instead of hydrofluoric acid or HF.

“As the Air Force project manager for a project to improve security in mission areas, this effort was one of the first I approved for funding because of its substantial impact on safety of personnel and the environment,” said Donna Spry, condition-based maintenance manager at Arnold Engineering Development Complex 804th Test Support Squadron. “I think this is one of the biggest improvements I’ve seen at AEDC in my 17 years.”

HF acid, a solution of hydrogen fluoride in water, is a corrosive chemical. According to the Centers for Disease Control and Prevention, “Hydrogen fluoride penetrates easily and quickly through the skin and into body tissues. There, it damages the cells and prevents them from working properly.

In the risk mitigation scheme, hazard removal is most effective, but substitution, which is what has been accomplished in the chemical cleanup yard, is considered second in effectiveness.

“Given the dangers associated with HF versus that of citric acid, this ranks as the most significant example of product substitution that I can recall in my 30+ years in the SHE [safety, health and environmental] in the field,” said Don Sproul, SHE Manager for Test and Sustainment Operations, or TOS, contractor for Arnold’s Engineering Development Complex. “This operation has been made considerably safer by this substitution, and all who have been involved in making it happen should be very proud of their achievement. Opportunities for improvement exist all around us. Please continue to build on this beautiful example to make AEDC a safer place for all.

The journey to HF acid replacement began when Warner Holt, Manufacturing Services Group Manager for Contractor TOS, spoke with aerospace exterior machinists Scottie Stevens, Scott Pogue and Bruce Prater to learn more about their work in the chemical cleaning site. He knew that they worked with acids, but while speaking with them he learned how dangerous one of the acids, HF acid, is for people and the environment.

“It really worried me,” Holt said. “I started doing research, and this stuff goes through skin and starts eating bone. It’s very dangerous. You can do damage over time, and it showed pictures of people who had worked with it at over the years and their fingertips had worn away where they weren’t protecting themselves.

The necessary personal protective equipment and procedures to protect personnel and the environment from exposure to HF acid were in place, but as long as HF acid was used there was a risk that something could go wrong. wrong.

After meeting with Arnold AFB Fire and Emergency Services and base security, a search began for a replacement.

“That’s when we started working with the chemistry lab and using their expertise and knowledge of chemistry,” Holt said. “We said, ‘Hey, we have hydrofluoric acid now and we need something that allows us to do the same kind of cleaning without having to use hydrofluoric acid.’

Megan Rawls, a metallurgical lab engineer in the base’s chemistry lab at the time, spent several months testing cleaners and identified two citrus-based products that could replace HF acid.

“I’m so proud of the teamwork of the craft staff, TOS management, chemistry lab, as well as the support of the fire and emergency services and TOS Safety to come up with a viable option for replace HF acid with a much safer alternative,” Spry said.

Once the substitutes were approved, it took several months of preparation, including the removal of the HF acid, which must be handled as a hazardous material even after being neutralized.

With the new products in place, the chemical cleaning yard was up and running again, with much less risk to the crew working there.

“It’s good,” Stevens said. “That’s really nice. You put on one of those banana suits [yellow Tyvek suit] and you’ll be wet by the time you get back there. Heat stress will be much better tolerated now. And, you’re not worried about a pinhole forming in a tank and blowing sideways as you walk. A catastrophic failure could occur.

“The environment matters a lot too. We don’t want to let anything out that doesn’t need to come out, so that’s a big plus.

When using HF acid, they had to dress fully in Tyvek suits, face shields, respirators, rubber gloves and rubber boots because any contact, including inhalation, was dangerous .

When using the new products, they only need long sleeves, long pants, rubber gloves and face shields in typical operations using a crane to lift and lower parts into and out of the tanks.

For environmental safety controls, a liner prevented acid from coming into contact with the floor in the tank and parts drying area. New products do not require this precaution. This reduction in environmental risk allowed the cancellation of a project to reline the drying area, in turn generating cost avoidance.

Besides the reduced risk, the only difference may be a slight increase in the time a part must stay in the acid to become as clean as with HF acid.

“There might be an argument that it’s not as good as the HF, but I’m going to take that rather than put these guys at that risk,” Holt said.







Date taken: 23.08.2022
Date posted: 23.08.2022 11:00
Story ID: 427850
Location: ARNOLD AIR FORCE BASE, TN, USA






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