Perruchini full shell moulding process for very low temperatures
18 May 2012
The increasing presence of mining and mineral exploration plant in polar areas has necessitated the development of new materials and products able to function perfectly at temperatures lower than 40 degrees below zero.
Atos low temperature Ex valves manufactured from metal moulded using Perruchini's full shell moulding process
Perucchini, part of the Atos group, has developed an innovative moulding process that successfully counters the decrease in material resilience at low temperatures.
These temperatures can cause failure in traditional components made from standard commercial cast iron and steel. Below a critical temperature, many kinds of steel lose their natural ductility and become extremely fragile and subject to fracture. These fractures are sudden and unpredictable, unlike more typical ductile fractures, which are preceded by plastic deformation of the metallic structure.
Perucchini castings for low temperatures (<-40°C), used in refrigeration, storage and transport of oil and gas, as well as by the military, are manufactured from special austenitic steels with a face-centered-cubic (FCC) crystal structure. These are capable of dissipating the tensile strain energy from the plastic deformation of the crystal structure at very low temperatures.
Perucchini’s special full shell moulding process also provides:
• steel and cast iron castings with no carbides or porosities
• complex shapes and thin walls
• close dimensional tolerance ranges (CT6-CT7 as per UNI ISO 8062 norm)
• reduced draft angle (0°30’-1°)
• low surface roughness (Ra 6.3 µm)
• large reduction of machining costs
The process is used in components for Atos on/off and proportional rust-proof hydraulic valves, with Atex, UL and Rostechnadzor certification, used in electrohydraulic plant in low-temperature applications such as these oil pumps in Siberia.
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