A Positive Chemical Reaction
Reliable Supply, Variety of Packaging Make Praxair Your Top Chock for Acetylene
Acetylene, an “old reliable” among fuel gases in metal fabrication, is experiencing something of a renaissance today. Users are increasingly employing acetylene in processes such as flame hardening in oil and gas field operations and vacuum carburizing for heavy machinery and automotive parts. The semiconductor and glass industries, among others, are creating new uses for this traditional colorless, highly flammable — but highly practical — fuel gas. While it’s seeing a newfound diversity of uses, acetylene continues as the fuel gas of choice for metal cutting, brazing and welding, particularly manual cutting applications. But recent supply availability has made it increasingly more difficult to find — and secure — a steady, reliable supply of acetylene. To help restore some security to the acetylene supply chain, Praxair recently signed a multi-year agreement with one of North America’s largest chemical acetylene manufacturers, allowing Praxair to offer a long-term supply of acetylene to metal fabrication shops across the continent.
Chemical vs. Generated
Many metal fabrication customers count on Praxair to deliver a reliable, high-purity supply of acetylene for their cutting and welding needs. Praxair’s service provides several advantages for customers, starting with its acetylene supply. Praxair distributes both generated acetylene, which is generated through a controlled reaction of calcium carbide and water, and chemical acetylene, which is produced from the process of thermal hydrocarbon cracking.
“ Praxair can deliver acetylene to our customers when they need it without concerns about a possible service interruption.”
– John Byington, Praxair Business Manager – Fuel Gas
“The ability to manufacture industrial acetylene and have highly reliable sources for chemical acetylene gives us a redundancy in our supply chain that’s extremely beneficial to customers,” said John Byington, Praxair Business Manager – Fuel Gas. “Praxair can deliver acetylene to our customers when they need it without concerns about a possible service interruption.” Chemical acetylene gives users higher purity than industrial acetylene, which makes it more efficient in many applications. Chemical acetylene is guaranteed to be 98.5 percent pure, and Praxair typically exceeds that by delivering product with 99.2 percent purity. Generated acetylene is only 98.0 percent pure and contains unwanted contaminants not found in chemical acetylene – including ammonia, hydrogen sulfide, phosphine and arsine – that can affect product quality and performance. Praxair also enables customers to consume acetylene more efficiently by using dimethylformamide (DMF) as a stabilizing solvent for transportation and storage in their larger packages, including clusters and bulk trailers. DMF is far more stable than the most commonly used solvent, acetone, and helps maintain higher purity as acetylene is extracted from the cylinders. “When a cylinder is full, the amount of acetone that comes out mixed with the acetylene is less than one percent,” Byington said. “But as the cylinder empties, that figure increases to over six percent, affecting the quality of the acetylene. Dimethylformamide is forty times more stable as a solvent in acetylene and it typically does not vaporize with the acetylene as it’s withdrawn, therefore consistently delivering more pure acetylene through the life of the cylinder.”
A Supply to Meet Any Need
Customers enjoy an array of acetylene packaging options from Praxair, spanning from cylinders for small-scale operations to bulk acetylene trailers that enhance productivity and site safety for customers while also saving substantial labor time and costs. Single cylinders are available in capacities from 10-450 cubic feet, and Praxair also offers nine-cylinder clusters that benefit customers by extending the operating duty cycle and eliminating the need for frequent cylinder handling. Cylinder clusters are especially suited for metal fabrication and treatment applications such as oxy-acetylene cutting, heat-treating and vacuum carburizing. Praxair delivers chemical acetylene stabilized with DMF to large-scale customers with bulk acetylene trailers. The system includes large gas cylinders permanently mounted on a trailer with a combined capacity of 78,000-90,000 cubic feet. The cylinders are connected by a manifold that supplies a continuous flow of acetylene through one outlet to the customer’s use points. For additional customer convenience, Praxair maintains the trailer system (including all cylinder and manifold valves) and the off-loading station; the customer needs to manage only the outlet valve. With its combination of high purity gas, supply network, solvent choice and packaging options, Byington said that Praxair is well positioned as an industry leader in acetylene supply for all applications, old and new. “Our acetylene offerings reflect Praxair’s goals to help customers be more productive and reduce costs with smart, efficient and cost-effective solutions,” Byington said. “Whether it’s new processes like burn-ins of semiconductors or traditional metal cutting applications, we can deliver the right solution for our customers.
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