4.1 This classification is intended to encourage uniformity in reporting properties of MLS and Metal Layer gaskets, to provide a common language for communications between producers and users, and to guide engineers and designers in the application and construction of commercially available gaskets.

(A) This classification may also be used to classify Single Layer Steel (SLS) Gaskets.(B) Refer to Specification A666 or Specification A109/A109M for Stainless Steel and Low Carbon Steel, respectively. Other metals not referenced in the table or not covered by Specification A666 or Specification A109/A109M must be defined by the producer/user (that is, H - High Temperature Alloy).(C) Refer to Practice D1418 for general information regarding rubber coating types and use Classification D2000 to define the physical properties of the rubber. This physical property information is typically specified on the gasket drawing or the customer specification, or both.(D) Coated side as specified on part drawing.

4.2 Suffix Table 2 is provided to allow hardness designation for Active, Inactive, or Load Stoppers.

4.2.1 If suffixes are not to be used, only the basic callout from Table 1 is required. If a suffix is used for 1 layer, it must be specified for all layers, even if a "0" is used. It cannot be assumed that hardnesses of like layers are the same; if used, all layers must be specified separately. The first layer specified must be indicated on the part drawing. To use a hardness call-out, at the end of the base callout leave a space followed by the "HR" suffix with a series of suffix numbers to specify the hardnesses for each layer.

4.2.1.1 Example: ASTM F2325, A32ANBW11 HR252-Example from Table 1 modified to add hardness requirement for the three metal layers. Active layers 1 and 3 are designated to be the same, ¹/₄ hard steel. Stopper layer 2 is designated to be full hard steel.