API 5A3 C American Petroleum Institute – Recommended Practice on Thread Compounds for Casing, Tubing, and Line Pipe – Annex C, Penetration Test
Thread compounds seal pipe connections and take up the slack in joints to prevent leakage. Commercial thread compounds, such as those intended for underground pipelines, should have a consistency that allows for easy application at both room temperature and in colder environments.
Consistency is measured by a penetration test. Thread compounds tend to become firmer (decreased penetration values) with decreasing temperature. This test determines the penetration values of thread compounds at both a room temperature and a below-freezing temperature to assure that the material will remain pliable when cold.
Two samples are worked (60 strokes). A (25°C) penetration is then determined on the first sample. The second sample is cooled (-7°C) as per the method, and a penetration value is determined on the cooled compound. The penetration values at both temperatures are reported.