SCOPE. This chapter provides technical information and guidance for
the design, fabrication, and testing of the piping of hyperbaric systems.
This includes the complete network of all piping, fittings, and other
components required to conduct and control fluid flow in the various systems.
Items such as pumps, compressors, and pressure vessels are not included in
this chapter except as anchor points in flexibility and stress analysis.
PIPING SYSTEM CLASSIFICATION. The design of piping systems for
hyperbaric facilities is complicated by the wide variety in type and
criticality of piping and the large number of military, industry, state, and
local codes that may be applicable to some or all of the piping. Systems in
hyperbaric facilities are divided into four hazard categories in accordance
with MIL-STD-882, System Safety Program Requirements (Reference 1) by the
seriousness of the results of a component failure as follows.
Category I System. In this system, a component failure will result
in extreme danger to the PV occupants and possibly to the facility operators.
The probability of fatalities is very high. Example: Major rupture of
breathing gas inlet connection.
Category II System. In this system, a component failure will
result in the need to abort the operation or take immediate corrective
action. Example: Massive leak in the life support loop which removes CO2.
Category III System. In this system, a component failure will have
only a minor effect on the PV occupants. The operation can continue with
some inconvenience. Example: Breakdown in the potable water system.
Category IV System. In this system, a component failure will have
no significant effect on the system operation. Example: Breakdown in the
water supply to the wet pot.
The piping system is classified in this fashion because the procedures
required for the design, fabrication, testing, maintenance and repair or
modification, varies for each hazard category, to insure the optimum safety
level for the system occupants and operators.
The design, fabrication, and testing of Category I and II systems must
conform at least to the ANSI B 31.1 Code for Power Piping (Reference 2).
Category III and IV systems must conform to military building and
construction piping codes such as NAVFAC TS-15401 Plumbing of July 1980
Table 5-1 indicates briefly the codes, specifications, and standards which
are applicable to the various hazard categories and systems.