scope:

This Standard provides requirements for the design, fabrication, inspection, testing, marking, and stamping of pressure vessels for human occupancy, hereafter called PVHOs or chambers. This Standard also provides requirements for the design, fabrication, inspection, testing, cleaning, and certification of piping systems for PVHOs. A PVHO is a pressure vessel that encloses a human being within its pressure boundary while it is under internal or external pressure, regardless of the pressure magnitude. PVHOs include, but are not limited to, submersibles, diving bells, personnel transfer capsules, decompression chambers, recompression chambers, hyperbaric chambers, high altitude chambers, and medical hyperbaric oxygenation facilities. This does not include nuclear reactor containments, pressurized airplane and aerospace vehicle cabins, and caissons.

The requirements contained in this Standard are supplemented by the ASME Boiler and Pressure Vessel Code, hereafter referred to as the Code, and the ASME Code for Pressure Piping, B31.1 Power Piping, also referredtoherein as ASME B31.1.

In relation to the geometry of pressure containing parts, the following are considered to be parts of chambers:

(a) shells of revolution;

(b) openings andtheir reinforcement;

(c) nozzles and other connections;

(d) flat heads;

(e) quick-actuating closures;

(f) attachments and supports, including method of attachment;

(g) access openings;

(h) windows;

(i) where external piping is to be connected to the vessel;

(1) the welding end connection for the first circumferential joint for welded connections;

(2) the first threaded joint for screwed connections;

(3) the face of the first flange for bolted, flanged connections;

(4) the first sealing surface for proprietary connections; or fittings;

(j) pressure retaining covers for vessel openings;

(k) the first sealing surface for proprietary fittings for which rules are not provided by this Standard;

(l) devices providing pressure relief to a chamber.

Piping systems, as covered by this Standard, include all pressure piping and component parts which fall under the definition of breathing gas systems and life-sensitive systems as defined in Mandatory Appendix D. Piping systems subject to the requirements of this Standard include, but are not necessarily limited to, the following:

(a) piping systems communicating with chamber pressure;

(b) breathing gas supply systems;

(c) ballast blow systems in submersibles;

(d) hydraulic systems in diving bell or submersible handling systems.

Piping that is part of personal breathing equipment and cylinders and other containers used for the storage of gases are excluded from the requirements of this Standard.