handling non-corrosive flow media at room temperature , carbon steel provides the most cost-effective solution . |
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Commonly Used Materials |
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Carbon steel is a type of steel that , as the name suggests , has a higher concentration of carbon than other types of steel . Most types of steel have a relatively low carbon content of about 0.05 % to 0.3 %. In comparison , carbon steel has carbon content of up to 2.5 %. Carbon steel is stronger than stainless steel and is resistant to wear . Valves made of carbon steel can withstand high pressure , but are susceptible to corrosion , and can also be brittle due to the hardness of the material . |
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Some commonly used carbon steel materials for valve body are : casting steel ASTM A216 with grades WCA , WCB and WCC , forging steel ASTM grade A105 / A105N , and low temperature carbon steel ( ASTM A352 LCB , LCC , ASTM A350 LF2 ). Among the three casting steel grades WCA , WCB and WCC , WCB is commonly used in oil & gas industries for regular temperature applications , and it is the casting version of forging steel ASTM grade A105 .
As mentioned previously , when selecting material for the valve body , based on the material processing methods , there are forged and casted steel , i . e ., for a particular specification and grade of forged steel , there is a corresponding casted steel with same chemical components . These can be used equivalently for chemical and mechanical properties .
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However , forging steel provides better uniformity of composition and structure than casted steel .
Forging leads to metallurgical recrystallization and grain refinement due to thermal cycle and deformation process , which strengthens the resulting steel products , especially in terms of impact and shear strength . Forged steel is generally stronger and more reliable than casting and plate steel , since the grain flows of the steel are altered , conforming to the shape of the part . Forged steel valves are mainly used in long-distance
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oil and natural gas pipelines , and other high-pressure industrial pipelines .
Some of the commonly used forged steels for manufacturing valves are :
1 . ASTM A105 / A105N
2 . ASTM A350 LF2
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3 . ASTM A182 F304 / F316 / F304L / F316L / F347
4 . A182 F51 / F50 ( Duplex 2205 )/ F53 / F55 / F60
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ASTM A105 / A105N steels are suited for fluid flow requiring assured performance , tight shutoff , constant torque , and no maintenance . ASTM A105 is the most used carbon steel forging material grade in manufacturing forge piping components such as valves . This carbon steel grade is used for ambient and higher temperature service in pressure systems . The ‘ N ’ in A105N stands for ‘ normalization ’ of A105 . The normalizing heat treatment will ensure the forging has superior properties to the ‘ as forged ’ material . |