SAE-AMS-2644

SAE-AMS-2644 is a standard developed by the Society of Automotive Engineers (SAE) that defines the requirements for non-destructive testing (NDT) penetrant materials used in liquid penetrant inspection (LPI) processes. This inspection method is widely used in various industries including aerospace, automotive, and manufacturing. It is used to detect surface discontinuities such as cracks, porosity, and inclusions in non-porous materials like metals, ceramics, and plastics. This specification is part of the Aerospace Material Specifications (AMS) series.

Key Features of SAE-AMS-2644

AMS-2644 covers the composition and performance characteristics of penetrant materials used in liquid penetrant inspection. These materials include:

Types and Methods

The specification classifies penetrants into different types based on their removal method

Type I: Fluorescent penetrants, which require ultraviolet (UV) light to detect defects.
Type II: Visible penetrants, which are detected in normal light and do not require UV light. These penetrants can be further categorised based on their method of removal:

Method A: Water-washable penetrants.
Method B: Post-emulsifiable, lipophilic (oil-based) penetrants.
Method C: Solvent-removable penetrants.
Method D: Post-emulsifiable, hydrophilic (water-based) penetrants.

Sensitivity levels

In this context refer to the ability of a penetrant to detect surface discontinuities, such as cracks, porosity, or other defects. Higher sensitivity levels indicate that the penetrant can detect smaller and finer indications.

AMS 2644 defines five sensitivity levels for fluorescent liquid penetrants:

1. Level ½: Very low sensitivity.
2. Level 1: Low sensitivity.
3. Level 2: Medium sensitivity.
4. Level 3: High sensitivity.
5. Level 4: Ultrahigh sensitivity.

The choice of sensitivity level depends on the specific application and the type of defects being sought. For example, a high-sensitivity penetrant might be necessary for detecting very fine cracks in critical components, while a lower sensitivity level might suffice for general inspections.

Key factors to consider when selecting a sensitivity level:

• Nature of the defect: The size, shape, and orientation of the defect will influence the required sensitivity.
• Material properties: The surface finish, porosity, and other material characteristics can affect the penetrant's ability to reveal defects.
• Inspection requirements: The specific standards or regulations governing the inspection will dictate the minimum sensitivity level.