1.2 Codes, Referenced Standards & the Medical Gas Team
Key Takeaways
NFPA 99 Chapter 5 covers gas and vacuum systems: 5.1 for Category 1, 5.2 for Category 2, and 5.3 for Category 3. Chapter 15 covers dental gas and vacuum systems.
For cryogenic fluid central supply systems, the source valve marks the boundary between NFPA 55 and NFPA 99.
Brazing procedures and brazers are qualified to ASME Boiler and Pressure Vessel Code Section IX or AWS B2.2, as modified by NFPA 99.
Inspections and verification tests must be performed by a party other than the installing contractor. Inspectors are certified to ASSE 6020 and verifiers to ASSE 6030.
New construction must meet the current code. In an existing system, only the altered portion must comply unless the authority having jurisdiction finds a distinct hazard to life.
How the Rulebook Is Organized
NFPA 99, Health Care Facilities Code is the core document for this exam. Installers mostly work in Chapter 5, Gas and Vacuum Systems, but several other chapters feed into it:
| NFPA 99 location | What it gives the installer |
|---|---|
| Chapter 1 (Administration) | Applies requirements to new construction and new equipment; the altered portion of an existing system must comply |
| Chapter 3 (Definitions) | Exact meanings of terms such as station outlet, zone valve, and medical support gas |
| Chapter 4 (Fundamentals) | Risk categories that decide whether a space needs Category 1, 2, or 3 systems |
| 5.1 | Category 1 piped gas and vacuum systems (the full rule set) |
| 5.2 and 5.3 | Category 2 and Category 3 systems, mostly by reference back to 5.1 with listed exceptions |
| Chapter 15 | Dental gas and vacuum systems |
The existing-systems rule in Chapter 1 is easy to test. Only the altered, renovated, or modernized portion of an existing system has to meet the installation and equipment requirements. Further upgrading is required only if the work would hurt the existing system's performance. An existing system that does not strictly comply may stay in service unless the authority having jurisdiction (AHJ) decides it is a distinct hazard to life.
Editions matter. NITC's exam uses NFPA 99-2024 together with ASSE Series 6000. A job site, however, follows whatever edition the AHJ has adopted. Some plumbing codes, such as the Uniform Plumbing Code's health care chapter, extract NFPA 99 text with paragraph references. Learn the 2024 rules for the exam and confirm the adopted edition before you install.
Referenced Standards You Must Recognize
| Standard | Why it appears in medical gas work |
|---|---|
| ASTM B819 | Seamless copper medical gas tube for positive-pressure systems |
| ASTM B88, ASTM B280 | Copper tube options permitted for vacuum piping |
| ASME B16.22 / ASME B16.50 | Wrought copper solder-joint fittings and wrought braze-joint fittings |
| AWS A5.8 | Specification for brazing filler metals (BCuP and BAg series) |
| ASME BPVC Section IX or AWS B2.2 | Qualification of brazing procedures and brazer performance |
| CGA G-4.1 | Cleaning equipment for oxygen service |
| CGA V-1 | Cylinder valve outlet and inlet connections (manifold leads) |
| CGA V-5 | Diameter Index Safety System (DISS) noninterchangeable threaded connections |
| CGA M-1 | Bulk/cryogenic supply systems (verification by ASSE 6035 personnel) |
| ASME B1.20.1 | Tapered pipe threads for the few threaded joints that are permitted |
| MSS SP-58 | Pipe hangers and supports |
| ASME BPVC Section VIII | Unfired pressure vessels, such as air and vacuum receivers |
| CDA Copper Tube Handbook | Brazing technique that NFPA 99 references for heating and filling joints |
| NFPA 55 | Compressed gases and cryogenic fluids |
The NFPA 55 boundary: for cryogenic fluid central supply systems, NFPA 99 adopts NFPA 55 language that makes the source valve the line between the two codes. Everything from the bulk vessel up to the source valve falls under NFPA 55. The pipeline on the facility side of it falls under NFPA 99.
Who Does What
| Role | Qualification | Typical responsibility |
|---|---|---|
| Designer | ASSE 6060, or another qualification the governing body accepts | Lays out sources, sizes piping, locates valves and alarms |
| Installer / brazer | ASSE 6010 | Installs piping and components; performs installer tests |
| Cryogenic installer | ASSE 6015 | Installs permanently installed bulk cryogenic supply systems |
| Inspector | ASSE 6020 (or 6030) | Inspects before piping is concealed; can witness installer tests |
| Verifier | ASSE 6030 | Performs system verification after the installer tests are complete |
| Cryogenic verifier | ASSE 6035 | Tests cryogenic fluid central supply systems under CGA M-1 |
| Maintenance personnel | ASSE 6040 | Maintains systems that are already in service |
| Instructors | ASSE 6050 / 6055 / 6070 | Teach the qualification courses |
| AHJ | Government or designated official | Approves plans and permits; can witness tests |
| Responsible facility authority | Qualified person named by the facility | Operates and manages the systems after turnover |
Independence is written into the code. System inspections must be performed by a party other than the installing contractor, and so must verification testing. When the facility's own staff did not install the system, the facility's qualified personnel may perform the inspection or the testing. When the facility's own staff did install it, an outside party is required.
Finding Topics in NFPA 99-2024 Chapter 5
Course materials and exam questions often cite paragraph numbers. The major Chapter 5 divisions for Category 1 systems are:
| Paragraph | Topic |
|---|---|
| 5.1.3 | Central supply systems (sources) |
| 5.1.4 | Valves |
| 5.1.5 | Station outlets and inlets |
| 5.1.6 | Manufactured assemblies |
| 5.1.7 | Surface-mounted medical gas rails |
| 5.1.8 | Pressure and vacuum indicators |
| 5.1.9 | Warning systems (alarms) |
| 5.1.10 | Distribution: piping materials, joints, brazing, installation, installer and brazer qualification |
| 5.1.11 | Labeling, identification, and operating pressures |
| 5.1.12 | Performance criteria and testing (5.1.12.2 installer tests, 5.1.12.3 inspection, 5.1.12.4 verification) |
| 5.1.13 | Medical support gases |
| 5.1.14 | Operation and management |
Paragraph numbers can shift between editions, so learn the topics, not just the numbers.
The Workflow in One Picture
The diagram after this text shows the normal order: design and approval, installation by ASSE 6010 personnel, inspection before concealment, the installer's tests, and finally independent verification before the system is used for patient care.
For an outdoor bulk cryogenic oxygen system serving a hospital, where does NFPA 55's jurisdiction end and NFPA 99's pipeline requirements begin?
At the first zone valve inside the building
At the vaporizer outlet
At the source valve
At the main line valve where the pipe enters the building
The installing contractor's own project foreman is a certified ASSE 6020 inspector. Can that foreman perform the system inspection required before the new piping is concealed?
Yes, because the foreman's ASSE 6020 certification is personal
No; inspections must be by a party other than the installing contractor
Yes, provided the AHJ witnesses the inspection
No, because only an ASSE 6030 verifier may inspect concealed piping
A clinic is renovating one wing of an older medical gas system that met an earlier edition of NFPA 99. Which statement reflects NFPA 99's rule for existing systems?
The entire facility system must be upgraded to the current edition before the work is accepted
Only the altered portion must comply, unless the AHJ finds a distinct hazard to life
Existing systems are always exempt from the current edition, even if the AHJ finds a distinct hazard
Only the source equipment must be upgraded to the current edition
Sections you finish are checked off in the contents.