Control Valves: Tackling A Burning Issue

Related Vendors

Elementar Analysensysteme GmbH

Donadon SDD Srl

Angst+Pfister AG

SAMSON AKTIENGESELLSCHAFT

Igniting Impurities

Burning the unwanted ingredients generates so much heat that the converters do not need to be heated from the outside to keep the raw iron molten. What is needed though is oxygen in abundance. It is blown into the converter from the top through a water-cooled pipe with a nozzle, the lance. The incoming oxygen creates a violent exothermic reaction that burns the impurities and also creates turbulence to mix the melt.

Frank Baltes of Samson, who coordinated the SMS Siemag order for India from the Samson office at Krefeld, Germany, knows what it comes down to: “The exact timing and dosage of the blown-in oxygen are crucial. In the process, pure oxygen at a high pressure is handled. Under such conditions, the impact of a small dirt particle can suffice to create a spark and ignite the metal equipment.” This risk is particularly high in the valve, where the gas flow is deflected and subjected to mechanical influence.

Finding the Right Alloy

There is not one single metal that is resistant to oxygen fire. Nevertheless, different metals and alloys show varying degrees of ignition susceptibility. Mr. Baltes describes the challenge involved in material selection as follows: “We need to find the right material and wall thickness ‑ taking into account a sufficient safety margin ‑ to prevent an ignition even under the most unfavorable of conditions. We calculated several sizing alternatives to match the special requirements. Finally, the customer decided in favor of a Type 3241 Valve with a stainless steel body and a seat and plug trim made of Monel®.”

Monel is an alloy that contains approximately 65 % of nickel, 33 % of copper and 2 % of iron. It is characterized by a high tensile strength and, more importantly in this case, a very high resistance to oxygen.

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