This specification covers stress relieved annealed electric resistance welded and cold-drawn single-wall high strength low alloy steel tubing intended for use in hydraulic pressure lines and in other applications requiring tubing of a quality suitable for bending, flaring, cold forming, and brazing.
The grade of material produced to this specification is of micro-alloy content. Nominal reference working pressures for this tubing are listed in ISO 10763 and SAE J1065.
CAUTION: Sub-critically annealed steels are often produced using anneal temperatures below the Lower Critical Temperature (AC1) of the given steel to achieve the desired strength levels. Welding, brazing, or other processing methods that subject the tube material or assembly to temperatures near or above AC1 might initiate isothermal transformation of the tube microstructure and compromise the strength of the tube in the heat affected zone by further annealing the tube. Therefore, ISO 10763 and SAE J1065 nominal reference working pressures might not be applicable. It is recommended that the user and the fabricator validate and agree that the tube assembly design and pressure ratings are not compromised beyond system design from these processes. Performance testing as described in SAE J2551-2 will facilitate appropriate test recommendations.
Brazed and/or welded tube assembly configurations made to specific geometry and components in association with this material may require qualification testing in accordance with ISO 19879 Test Methods for Hydraulic Fluid Power Connections. Cold forming the tube end connections in place of thermal processes such as brazing and welding avoids this systemic testing by not compromising the structural integrity of the tube material.
In an effort to standardize within a global marketplace and ensure that companies can remain competitive in an international market, it is the intent to convert to metric tube sizes which will:
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Lead to one global system
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Guide users to preferred system
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Reduce complexity
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Eliminate inventory duplications