ASTM D5534 Steel Test Specimen

1018 steel test specimens used in ASTM D5534 (Vapor-Phase Rust-Preventing Characteristics of Hydraulic Fluids). This test method uses two types of test specimen: a horizontal steel disk and a vertical steel cylinder. The horizonal specimen allows water to puddle on the steel surface, and the vertical specimen is continually washed with the oil-water test fluid during the test.
The horizonal specimen is 1-3/16" in diameter and 3/16" thick with a 1/4" central threaded shaft that is 3/8" long. 
The vertical specimen is 1/2" in diameter and 1" long (3/8" threaded shaft to attach to the horizontal specimen, 5/8" length excluding the threaded shaft). 
The specimens are attached using a 3/32" fluorocarbon washer. 
The test specimen and apparatus used in ASTM D5534 are identical to those used in ASTM D3603 (Rust-Preventing Characteristics of Steam Turbine Oil in the Presence of Water - Horizontal Disk Method)