Section 2. MATERIALS FOR HYPERBARIC VESSELS
1.
MATERIALS. This section contains guidelines for classifying materials
and components within the Scope of Certification & Safety Standards herein.
Classification of a material or component is dependent on its application and
service experience. A material or component which has had previous
experience or use in a Naval environment does not, however, automatically
place it in Class 1. The proposed application, configuration, design
concepts, and joining techniques must be reviewed to determine the proper
class for each material or component. In other words, previous Naval
experience in an application or configuration which cannot be correlated to
the proposed application or configuration would, in general, disqualify the
item for Class 1 and place the material or component in Class 2, which would
require additional proof testing to justify its use. It is emphasized that
the material and component classes detailed in this manual should not be
confused with the hazard level categories of MIL-STD-882. The material and
component classes of this manual were conceived to aid in assessing the
reliability of materials and components in specific hyperbaric applications.
They do not, in all cases, correspond to the MIL-STD-882 hazard level
categories which are assigned to the possible failure of such materials or
components.
The applicant must justify the materials and their applications as used
in the design of the hyperbaric facility for the expected service
environments. All of the materials considered to be within the certification
scope shall be identified. The relative location of the materials should be
included and verification of their compatibility problems are a concern.
2.
MATERIAL CLASSES. It is anticipated that some hyperbaric facilities
will be designed to operate at greater depths and that new materials, new
applications for time-tested materials, and new configurations may be
employed. It is not the intent of this manual to limit the materials and
their applications. The intent is to permit the use of new materials in new
applications whenever sufficient data exist to show that the material
adequacy of the hyperbaric facility, and hence, the safety of the personnel
utilizing the facility is reasonably assured. The less the amount of
available information and experience with a material or application, the
greater the burden upon the applicant to justify the adequacy of the proposed
material or application. For the purpose of System Certification, the
possible materials and/or components are grouped into the following three
classes:
a.
CLASS 1, Material of proven characteristics. In general, Class 1
materials and components are those for which considerable operating
experience is available. For pressure vessel materials and external piping
within the boundary of certification, this would include experience in
fabrication, testing and operation in a marine environment. For piping
systems, compatibility with the internal medium would also have to be known.
The following is a list of typical materials and components which are
generally considered to fall into Class 1. Untested or unusual
configurations or applications of these materials and components might,
however, place them in Class 2.
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