WELDNECK
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Carbon Steel

The workhorse grade family. Covers the majority of industrial pressure service from refinery process to pipeline pressure to waterworks. Five major grades each have a distinct application envelope.

A105 Forged Carbon

36 ksi minimum yield, 70 ksi tensile. The default forged carbon weld neck grade for room-temperature pressure service. Covers ASME B16.5 catalog in all standard pressure classes. Minimum design metal temperature minus 20 degrees F without impact testing. Above 800 degrees F, ratings derate sharply per ASME B16.5 P-T tables.

A350 LF2 / LF3

Carbon and carbon-nickel forged grades with mandatory charpy impact testing. LF2 covers minimum design metal temperature to minus 50 degrees F. LF3 contains 3.5 percent nickel for service to minus 150 degrees F. Both are dimensionally identical to A105 and substitute where the project specifies low-temperature pressure service.

A516 Grade 70

Pressure-rated plate. 38 ksi yield, 70 ksi tensile. Default plate for blind flanges, ring flanges, and the plate-cut face of hubbed weld neck flanges in pressure service. Normalized when section thickness exceeds 1.5 inch. Charpy impact testing optional for low-temperature service.

A36 Structural Plate

36 ksi yield structural plate. Used on AWWA C207 lightweight flanges and on non-pressure structural flange applications. Not pressure-qualified for ASME service. A36 should not substitute for A516-70 on pressure drawings.

A694 High-Yield Pipeline

Forged carbon with elevated yield strengths matched to API 5L X-grade pipe. Grade designators F42 through F70 where the number is the minimum yield in ksi. MSS SP-44 pipeline weld neck flanges are the typical application. Normalize-and-temper or quench-and-temper heat treated. Charpy impact testing mandatory above F52.

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