Class 1 Piping Materials
Flanges & Fittings ASTM A-350
MIL-T-1368 Class A, ASTM B-466
MIL-C-15726 ASTM B-402, Alloy 715
MIL-T-16420 ASTM B-466, Alloy 715
MIL-B-16541 ASTM B-62
MIL-B-23921 ASTM B-271
(min. 4% Ni)
These are Class 1 materials only when fabricated and tested to appropriate
The use of Class 2 material in systems of hazard category I or II requires
the suppliers certificate supplemented by specific information to assure
When Class 3 materials are to be used in hazard category II or III systems,
additional justification in the form of documentation and material test
reports is required. Hazard category IV systems may be made up of
commercially-available materials and components without special
a. Justification of Class 2 Materials. As a minimum, the following
information will be necessary to justify the use of a Class 2 material in
category I or II piping system.
(1) The applicable Military, Federal, or commercial specification
involved with a list of exceptions or additions.
(2) Tensile properties, including ultimate tensile strength,
tensile yield strength, percent elongation, and reduction of area.