In May 2020 I wrote Part I – General Requirements after OSHA issued two willful and three serious violations totaling $122,602 to a sperm bank for bulls (cattle) after an employee was asphyxiated while filling freezers with Liquid Nitrogen. And back in 2017, we saw another sperm bank, this one for humans, have a Nitrogen incident that claimed the life of a Deputy Sheriff and critically injured the supervisor of the business. I promised a Part II and III back then and I have been tardy in following up. But this week’s mass casualty event in Georgia involving liquid Nitrogen where six (6) workers have died at the time of this writing has spurred a lot of questions about the use of N2 in these enclosed workspaces. I will again use the 2015 International Fire Code (GA uses 2012 as their state code) in this article and in Part III which I will post next week. So what does the IFC require for the storage of liquid N2…
| SECTION 5504 STORAGE 5504.1 General. Storage of containers shall comply with this section. |
As with all HAZMAT chapters, there are sections specific to STORAGE and USE. In this section, we will cover the STORAGE aspects. The storage requirements are split into
- indoor storage locations, and
- outdoor storage locations
Whether cryogenics are indoors or outdoors will affect the NUMBER and TYPE of safeguards required.
| 5504.2 INDOOR STORAGE. Indoor storage of containers shall be in accordance with Sections 5504.2.1 through 5504.2.2.3. 5504.2.1 Stationary containers. Stationary containers shall be installed in accordance with the provisions applicable to the type of fluid stored and this section. 5504.2.1.1 Containers. Stationary containers shall comply with Section 5503.1. 5504.2.1.2 Construction of indoor areas. Cryogenic fluids in stationary containers stored indoors shall be located in buildings, rooms, or areas constructed in accordance with the International Building Code. 5504.2.1.3 Ventilation. Storage areas for stationary containers shall be ventilated in accordance with the International Mechanical Code. 5504.2.2 Portable containers. Indoor storage of portable containers shall comply with the provisions applicable to the type of fluid stored and Sections 5504.2.2.1 through 5504.2.2.3. 5504.2.2.1 Containers. Portable containers shall comply with Section 5503.1. 5504.2.2.2 Construction of indoor areas. Cryogenic fluids in PORTABLE CONTAINERS stored indoors shall be stored in buildings, rooms, or areas constructed in accordance with the International Building Code. 5504.2.2.3 Ventilation. Storage areas shall be ventilated in accordance with the International Mechanical Code. |
The indoor storage requirements are divided into stationary and portable containers. This section requires that indoor storage areas be constructed in accordance with the IBC and addresses occupancy requirements in terms of maximum allowable quantities (MAQs) and other relevant issues. Again, note that not all cryogenics have a characteristic that would classify them as hazardous in the context of MAQs.
Ventilation is more critical in indoor areas than in outdoor areas because fluids cannot disperse and be removed as easily. This section references the International Mechanical Code® (IMC®) for ventilation requirements. The IMC ventilation requirements in Section 502 – Required Systems are based on the space’s intended use. Chapter 50 also addresses ventilation requirements in Sections 5003.8 and 5005.2. These particular requirements apply ONLY when the maximum allowable quantities have been exceeded.
| 5504.3 OUTDOOR STORAGE. Outdoor storage of containers shall be in accordance with Sections 5504.3.1 through 5504.3.1.2.3. 5504.3.1 Separation from hazardous conditions. Cryogenic containers and systems in outdoor storage shall be separated from materials and conditions that pose exposure hazards to or from each other in accordance with Sections 5504.3.1.1 through 5504.3.1.1.5. 5504.3.1.1 Stationary containers. Stationary containers shall be separated from exposure hazards in accordance with the provisions applicable to the type of fluid contained and the minimum separation distances indicated in Table 5504.3.1.1. |
This section applies to OUTDOOR AREAS, which are generally less hazardous because released fluids disperse more easily, reducing the potential for harm to people in the surrounding area and property. Outdoor storage areas, however, are more susceptible to damage from both weather and people. As with the indoor area section, the requirements are divided into
- portable and
- stationary containers
These requirements emphasize that cryogenic containers and systems, whether for storage or for use, must be separated from other materials and conditions that could pose a hazard to them or when they could be hazardous to other materials. The two subsections that follow address stationary containers and portable containers.
This section references Table 5504.3.1.1 and notes that additional separation requirements for the fluids may increase this distance. For example, Table 5804.2.1 for flammable gases has more restrictive distance requirements in some instances. This table states that the minimum distance to buildings for 0 to 4,225 cubic feet (0 to 120 m3) of flammable gases is 5 feet (1524 mm), whereas Table 5504.3.1.1 requires only a 1-foot (305 mm) separation.
TABLE 5504.3.1.1 SEPARATION OF STATIONARY CONTAINERS FROM EXPOSURE HAZARDS | |
EXPOSURE | MINIMUM DISTANCE (feet |
Buildings, regardless of construction type | 1 |
Building exits | 10 |
Wall openings | 1 |
Air intakes | 10 |
Lot lines | 5 |
Places of public assembly | 50 |
Nonambulatory patient areas | 50 |
Combustible materials such as paper, leaves, weeds, dry grass, or debris | 15 |
Other hazardous materials | In accordance with Chapter 50 |
For SI: 1 foot = 304.8 mm. | |
This table has several different separation distance criteria for STATIONARY CONTAINERS. Generally, the distances are larger when exposure to people is involved, such as places of public assembly and areas where nonambulatory patients are housed. These restrictions are related more to the hazards associated with their low temperatures, high pressures, and asphyxiation hazards than they are to flammability or toxicity, which are dealt with in other chapters. Depending on these additional characteristics, larger distances to buildings and lot lines are sometimes required. Also, the restrictions in Table 5504.3.1.1 of the code are for any amounts of cryogens where the requirements for other hazards typically vary based on the volume of gas.
| 5504.3.1.1.1 Point-of-fill connections. Remote transfer points and fill connection points shall not be positioned closer to exposures than the minimum distances required for stationary containers. 5504.3.1.1.2 Surfaces beneath containers. Containers shall be placed on surfaces that are compatible with the fluid in the container. 5504.3.1.1.3 Location. Containers of cryogenic fluids shall not be located within diked areas containing other hazardous materials. 5504.3.1.1.4 Areas subject to flooding. Stationary containers located in areas subject to flooding shall be securely anchored or elevated to prevent the containers from separating from foundations or supports. 5504.3.1.1.5 Drainage. The area surrounding stationary containers shall be provided with a means to prevent accidental discharge of fluids from endangering personnel, containers, equipment, and adjacent structures or to enter enclosed spaces. The stationary container shall not be placed where spilled or discharged fluids will be retained around the container. Exception: These provisions shall not apply where it is determined by the fire code official that the container does not constitute a hazard, after consideration of special features such as crushed rock utilized as a heat sink, topographical conditions, nature of occupancy, proximity to structures on the same or adjacent property, and the capacity and construction of containers and character of fluids to be stored. |
Because there is a potential for a large release of cryogens from faulty connections, the same separation requirements found in Table 5504.3.1.1 would apply to the point-of-fill connection. To ensure that a reaction does not occur with the surface below the container in the event of a cryogenic spill, the surface beneath the container and its point of fill must be compatible with the fluid stored. The surface below the container must NEVER be made of materials that may become brittle when exposed to extremely low temperatures or be corroded by the stored fluid. Either embrittlement or corrosion could weaken the supporting structure and affect the stability of the container. Cryogenic fluids MUST NOT share diked areas with other hazardous materials because of the risk that one type of hazardous material could create an exposure hazard for the other. Cryogenics, if released, will be at very low temperatures and high pressures that could potentially compromise the integrity of the other containers and tanks.
Because stationary containers are considered permanent, issues such as flooding and the effect that flooding will have on the stability of the container are important. Flooding has the tendency to cause containers to pull away from their foundations because of their potential buoyancy. This section requires that the container either be anchored or elevated; if elevated, containers must be elevated to or above the elevation requirements of the IBC. Flood hazard areas are defined in IBC Section 202.
This section deals with both exposure hazards and the need to avoid a buildup of spilled fluids. People and property must be protected from the exposure hazards of the initial spill. How this is to be done is not specified because the needs for installation vary considerably. In terms of the drainage, if the fluids are released, they cannot be held in the immediate vicinity of the container; therefore, diking may be a practical method of containment, but the impounded spill would have to be diverted away from the container once it has been released. There is an exception for areas where the exposure hazards are very low, such as a container in a very remote location. Several factors need to be addressed before such allowances can be given. In some cases, a smaller container may be able to take advantage of this exception whereas a larger container may be based on the potential size of the discharge.
| 5504.3.1.2 Outdoor storage of portable containers. Outdoor storage of portable containers shall comply with Section 5503 and Sections 5504.3.1.2.1 through 5504.3.1.2.3. 5504.3.1.2.1 Exposure hazard separation. Portable containers in outdoor storage shall be separated from exposure hazards in accordance with Table 5504.3.1.2.1. |
Portable containers are typically smaller than stationary containers; therefore, the requirements are less detailed and are generally less substantial.
TABLE 5504.3.1.2.1 SEPARATION OF PORTABLE CONTAINERS FROM EXPOSURE HAZARDS | |
EXPOSURE | MINIMUM DISTANCE (feet) |
Building exits 10 | 10 |
Wall openings 1 | 1 |
Air intakes 10 | 10 |
Lot lines 5 | 5 |
Combustible materials such as paper, leaves, weeds, dry grass or debris | 15 |
Other hazardous materials | In accordance with Chapter 50 |
For SI: 1 foot = 304.8 mm. | |
Because portable tanks are generally much smaller than stationary containers and are more easily moved, the separation distances do NOT address areas of assembly or buildings housing nonambulatory patients. Instead, the focus is on exits and areas where portable tanks are more likely to cause an immediate threat. For those locations that correlate with Table 5504.3.1.1 of the code, the distances are the same. For instance, the distance to wall openings must be at least 1 foot (305 mm) for BOTH stationary and portable containers. Again, these separation requirements are for all amounts of cryogenics stored in PORTABLE CONTAINERS.
| 5504.3.1.2.2 Surfaces beneath containers. The surface of the area on which stationary containers are placed, including the surface of the area located below the point where connections are made for the purpose of filling such containers, shall be compatible with the fluid in the container. 5504.3.1.2.3 Drainage. The area surrounding portable containers shall be provided with a means to prevent accidental discharge of fluids from endangering adjacent containers, buildings, equipment, or adjoining property. Exception: These provisions shall not apply where it is determined by the fire code official that the container does not constitute a hazard. |
This section is identical in intent to Section 5504.3.1.1.2; however, because portable containers are not permanently attached to foundations or similar supports, they can be moved to various locations with different surfaces. Personnel responsible for handling and placing the portable containers must be trained in the interactions between cryogenics and certain materials. This section requires placing the containers in locations that will not further endanger buildings or other exposures in the event of a spill. If impounding is used to contain a spill, the spilled fluid must be diverted to a location where it would not cause personal injury or property damage. This requirement is in addition to the distances specified in Section 5504.3.1. As in Section 5504.3.1.1.5, an exception permits the fire code official to review container locations and evaluate the potential hazard of a spill. If the container’s arrangement does not create a hazard, compliance with this section is not required. A good example is a well-isolated storage area.