Water-Based Penetrants Get Their Own Classification: Method A(W)
One significant change in Revision G is the inclusion of a new class of penetrants, Method A(W). Method A(W) was created to distinguish between Method A penetrants that are water-based, and those that are oil or surfactant based. Previously, all Method A materials were lumped together, regardless of their chemical composition. This change was made to address the increased interest in the market for products that are water-based. Method A(W) penetrants are being defined as products that contain 20% or more water.
Additional changes were made to support the addition of Method A(W) to the specification, including:
- Addition of a flashpoint method that is compatible with aqueous materials.
- A require maximum water content limit of 5% for Method A, B, C, and D penetrants.
Updates to the Method A Penetrant Qualification Criteria
The next big update in Revision G is a significant change to the qualification criteria for Method A penetrants. Since its inception in 1996, the qualification criteria for AMS 2644 have undergone several changes as the lab at Wright-Patterson AFB improved the techniques used to test and approve penetrants. Although the qualification criteria changed, previously approved products were never required to be retested. This practice led to a situation where at least some of the penetrants listed on the Qualified Products List (QPL) would not meet the most current qualification criteria.
To address this, penetrant manufacturers were required to submit samples of all Method A penetrants to WPAFB. These penetrants were tested for sensitivity and removability, and new standards were designated to establish the minimum sensitivity and removability requirements for each sensitivity level. Method A(W) penetrants were also tested as part of this process, and they will be held to the same standards as the Method A materials.
Manufacturing Facility Consistency
Another significant update to revision G is a requirement for penetrant manufacturers to provide data demonstrating that their products are consistent between their manufacturing facilities. Only one sample from a single facility undergoes testing during the qualification process, causing a concern that individual products may vary significantly from one facility to another. To address this, supporting data should include material scans using either Fourier Transform Infrared Spectroscopy (FTIR) or Mass Spectroscopy (MS). The new requirement helps ensure manufacturers are providing products that are consistent across all manufacturing sites.
Planned changes for Revision H
Work has already begun to collect data for the next revision of AMS 2644. The plan is to have updated qualification criteria for Method B systems included in this revision. This update will be similar to the update to the Method A qualification criteria discussed above. WPAFB requested that manufacturers submit samples of all Method B materials by mid-March, 2019. No timetable is set for completion of this testing.
Understand fluorescent liquid penetrant sensitivity levels and how to find the right one for your application with this Guide to AMS 2644 Penetrant Sensitivity Levels article.
Published May 21, 2019