ISO 23936-2 is the international standard for RGD testing. Requirements for this test are meant to be challenging; Temperature set to 100°C, pressure set to 15 MPa, and a methane/CO2 environment. Testing samples are put through 8 cycles of pressurization and depressurization, including a single 68-hour exposure. After the test is completed, the sample O-rings are dissected and their cross sections are examined. Based on the damage observed, the specimens are given a rating of 0-5. Grades 4 and 5 are considered failures.
NORSOK M710 Edition 3
The NORSOK M710 Edition 3 is a Norwegian standard that is used to ensure materials used in the petroleum industry are safe and effective. M710 instructs the user to follow the ISO 23936-2:2011 standard for RGD testing.
The ISO also outlines the design for the fixture used in these tests. In the document, the written description and the provided drawing differ from one another. This discrepancy caused industry-wide confusion in the past, but Alpine offers both fixture designs to ensure that the tests return the results that our clients need.
A “gas trap” fixture is illustrated in ISO 23936-2:2011 Annex B, Section B.2. This fixture allows gas to contact the O-rings from one direction, accumulate between pairs of O-rings, and remain trapped during depressurization due to fixture design.
A “free flow” fixture is described in text in ISO 23936-2:2011 Annex B, Section B.1.23. This is an alternate fixture design that allows gas to contact all sides of each O-ring via added gas ports. Due to this, upon depressurization there is no trapped gas. This fixture usually causes much more damage to the O-rings being tested.
