Hose + Coupling World was happy to speak with Fred Schweighardt, an international expert in welding and cutting, and Chairman of the upcoming Hose + Coupling World Americas Conference & Expo in October 2018. He describes his new role as National Projects Leader for Airgas, an Air Liquide company, and his almost 20 years of experience serving the industrial gas industry as a welding expert.
By Jody Hewitt, Editor.
Airgas is the leading supplier of gases, welding equipment and safety products in the United States. Headquartered in Radnor, Pennsylvania, the Airgas network is comprised
of more than 900 retail locations, cylinder fill plants, gas production facilities, specialty gas laboratories and regional distribution centers.
Employing approximately 18,000 people across the nation and serving more than one million customers, Airgas supplies industrial, medical and specialty gases, carbon dioxide,
nitrous oxide, welding equipment and supplies, process chemicals and more to industries including: manufacturing and metal fabrication, construction, chemicals, life sciences and healthcare, food and beverage, materials and power, defense and aerospace.
“The industrial gas industry is very diverse,” says Schweighardt. “Your cellphone, the metal parts of your chair, the fizz in your soda… none of it would exist without industrial gas. We have an entire medical group that does nothing but medical gas. We have a food segment and they focus on ways that you use industrial gas in food. I focus on the ways you use industrial gas in welding.”
Hoses for cryogenic and high-pressure applications
As a welding expert, Schweighardt works with high-pressure and cryogenic hose applications. At temperatures as low as -320° Fahrenheit, metallic hoses are the standard, as few other materials can withstand this temperature without failing. “For cryogenic hoses there are a relatively small number of materials that are suitable for low or high-pressure and low temperature at the same time,” explains Schweighardt. “On top of that, the hoses still have to be flexible.”
In these applications, Schweighardt uses a hose with a stainless corrugated inner tube and a braided and/or armored stainless outer, which protects the inner tube during cryogenic transfer. If he is particularly concerned about the flow characteristics, Schweighardt will use a hose with a Teflon-lined inner tube to prevent any liquids from getting into the corrugated ridges of the metal.
“It has to be stainless,” he adds. “Stainless is the only material that is financially feasible and has all the requisite mechanical characteristics that allow it to be flexible in low temperatures or under moderate pressure – up to 1500 pounds per square inch (psi). What we’re looking for is ductility and low-temperature resistance. Austenitic stainless steels have a special microstructure that causes the metal to retain its ductility at a low temperature.”
Respect the bend radius for best results
As with all hoses, the single biggest threat to the health and longevity of a hose, whether it is a common garden hose or a two-thousand-dollar cryogenic hose, is not respecting the
“Over-bending is the number one thing that will bring a hose back for warranty or repair,” explains Schweighardt. “Any reputable hose supplier will tell you what the bend radius of a hose is. Say a hose has a bend radius of 30 inches – if you try to wrap that hose around a barrel that is two feet in diameter, a 12-inch bend radius, it is going to cause problems.”
Naturally, the damage is going to be worse at the coupling end of the hose, where the hose becomes rigid – especially when it is fastened with a coupling that is itself rigid.
Schweighardt uses the example of a garden hose: “If you screw a garden hose onto your house, and then walk around the corner and start pulling, the first place that your hose kinks and bends and squeezes flat is right by the faucet. It is that transition that experiences the most stress; where it goes from being most flexible to rigid. It is also the
part that gets all the wear.”
Schweighardt and his team are careful not to over-bend hoses, not least because Airgas’ least expensive hoses are a couple hundred dollars, but also because of the hazardous
material or incredible amount of pressure contained within.
“We have some fairly high stored energy inside our hoses,” says Schweighardt. “In our high-pressure hoses, there can be as much as 6000 psi in there, so we want to take care of
it and make sure it is working properly.”
Choosing the right connection
In the industrial gas industry, the Compressed Gas Association (CGA), a consensus organization comprised of members from all facets of the industrial and medical gases
and equipment industry in the United States and Canada, determines the best and safest connections for liquefied, non-liquefied, dissolved, and cryogenic gases.
Its mission is to improve the manufacture, transportation, storage, transfilling, and disposal of industrial and medical gases and their containers by developing internationallyrecognized
standards and practices, providing safety information about the chemical properties of gases, and providing training, leadership and advocacy to its members and the industry as a whole.
“The CGA decides, in a very company-agnostic way, that certain connections should be designed in a certain way,” explains Schweighardt. “The CGA determines the direction
of the threads, size, sealing mechanism and male-female parts for any connection, and you cannot interconnect anything that should not be interconnected.”
As per the standards set by the CGA, Airgas uses many dozens of different connectors and couplings that are specific to the material that is being used. For example, if the material
is liquid nitrogen, there is a special type of fitting that is used for liquid nitrogen and nothing else. This is no accident.
“Liquid nitrogen comes in at least four sizes,” he continues. “Three standard large sizes and one standard small size. Obviously, if you try to connect the small coupling to the large tank connection, it won’t match up because of the size difference, but if you go get the liquid oxygen couplings, they won’t match up either. This is because they were designed
not to match up with a tank of anything but liquid nitrogen.”
The idea is to minimize or eliminate the risk of user-error, which, considering the properties of the materials, could have serious repercussions. “All Airgas products have a different special connection. This is true of all of the trucks and tanks that are delivered to our customers.”
To read the full interview with Fred Schweighardt, contact the Editor.