Q3 2008 / UN regulates changes in cylinder markings worldwide

DOT cylinders no longer are recognized as the “official” cylinders of the United States. A second issue: Not all valves are created equal. 

Major changes involving cylinder markings have been in the background, often unnoticed, ever since President Ronald Regan signed into law legislation that had the effect of a treaty. Most of you may not yet realize what has been happening, why it is happening, and how it affects you and everyone else who deals with compressed gas cylinders.  

In all probability, most of you have lived in the era of DOT cylinder specifications. Before the emergence of DOT, in the late 1950s, we old-timers lived in the ICC era, during which, cylinders were marked with the identifier ICC (Interstate Commerce Commission) preceding the materials specification for the cylinder. Thus, a cylinder marked with ICC 3A during that early time, would later be marked with DOT 3A, and more often recently as DOT 3AA. (The “3AA” refers to a steel specification.) 

While the “official” cylinders in the United States were marked “DOT” for more than 50 years, that is all changing.  

In an effort to bring the United States more solidly into a global economy, Congress passed and President Regan signed legislation that “treaty” mentioned earlier. That legislation basically states that if the specification for a shipping package or container is accepted by the United Nations, that specification could be “adopted” by the Department of Transportation and become the law of the land.  

Notice of proposed rulemaking eliminated 

What needs to be understood is exactly what effect this legislation has had; i.e., what has happened and how it is happening.  

Until now, if the DOT wanted to change a regulation in its section of the law; e.g., CFR (Code of Federal Regulations) Section 49, it had to follow several steps. The first step required that an NPR (Notice of Proposed Rulemaking) had to be issued. This notice gave the public the right to comment or complain about the changes being proposed. In some cases, changes could be rolled back through “grass roots” campaigns, or through a powerful Congressman who could be reached and influenced.  

That right has been taken away. With the signing of the “treaty” legislation, any item that has been adopted by the UN, as well as by the DOT (providing it is not an unsafe action), the change goes directly into the Federal Regulations. There is no comment period. The change simply appears in the published regulations. Since the U.S. legislation has the effect of a treaty, actions taken by the UN and the DOT supersede the laws of the U.S.  

UN markings replace DOT 

Although relatively unnoticed, this situation has been in effect for some time, and has affected cardboard boxes, steel drums, and other containers used for shipping. If you look closely on any of these containers, you will note the “UN” markings, but there is no reference to DOT.  

A major change that will affect the compressed gas industry is that the aforementioned DOT cylinders no longer are recognized as the “official” cylinders of the United States. These formerly “official” cylinders are still “authorized” to the extent that they can still be made and, for the time being, sold for use in the United States. The “official” U.S. cylinder is really the UN cylinder.  

If you read the 49 CFR very carefully, you will find several new paragraphs that have been added. For example, 173.301b and 173.302b specifically address only UN cylinders. Another major change is that the construction specifications are now ISO standards, not the specifications found in 49 CFR. 

Not all valves are created equal 

One significant difference between the UN and U.S. cylinders, that could affect you, is that the taper on the valve threads (between the cylinder valve and the cylinder itself) is different on valves made for current DOT cylinders and valves made for UN specification cylinders. Since several of the valve diameters are the same, valves can inadvertently be intermixed. If a valve made for a UN cylinder is threaded onto a DOT cylinder, there will be only one thread of engagement – not a very desirable condition. 

The ISO system, as incorporated by the DOT for UN cylinders, mandates that both the cylinder and the valve be marked with a code that makes it possible for the user to ensure that the correct combination of valve and cylinder has been used. This check can be made even after the cylinder is valved since both the valve and cylinder codes must be identical.  

This is unlike the current U.S. system, which makes it possible for a post medical valve to be inserted into an “E”-sized gas cylinder threaded for tapered valves. In such cases, since there is no U.S. marking system in place, the error can be detected only if gas is leaking and is detected or if the valve is ejected by the force of the compressed gas.  

CGA spots potential problem, offers solution 

Once this potential problem was recognized, the CGA (Compressed Gas Association) wrote a new update to its standard CGA V-9 Compressed Gas Association Standard for Compressed Gas Cylinder Valves. It is expected that the DOT will (when the standard is submitted to it) incorporate it by reference into 49 CFR.  

That V-9 standard has a valve thread coding system that mandates that all new valves be marked using it. Although current DOT cylinders are not required to be marked with the tread codes, we can assume that all current DOT cylinders would need the U.S. coded valves,  

It is hoped that at some future date, the U.S. DOT cylinder industry will begin to use and mark the U.S. codes. Note that the CGA standard V-9 contains a grandfather clause that covers valves currently in service or in inventory. So you will probably be seeing V-9 compliant valves (marked V-9 and with the tread code) when you buy new valves. Valves that are properly marked are currently available from most valve vendors, but if you don’t ask for them, you could be getting old stock.  

DOT cylinders lack UN requirements 

Also, you should be aware that the UN cylinders are required to use valves that meet the current ISO valve standard, which includes minimum pressure and cycle life requirements. DOT cylinders in the United States have no such requirements. The only existing requirement is that the cylinder valve or closure not leak when shipped. This means that you can literally use a water faucet on a cylinder and still meet the current requirements.  

This is another part of CGA V-9 that is badly needed, and will be addressed when V-9 is incorporated by reference. As I have said often, “When you are dealing with the U.S. DOT, you are in fact literally dealing with possibly the only government agency that when they say ‘I’m from the government and I’m here to help you’, that they mean it.” 

Cylinders improperly used threaten re-fillers 

One of the real dangers in the use of compressed gas cylinders does not necessarily affect the using public; the greater danger is to the cylinder filler. The problem related here arises when the user does something improper to the cylinder or adds some foreign substance into the cylinder. When that cylinder is returned to the filling company, the cylinder filler is at risk. (See Safety Alert on page 8, in North America News Section.)  

One of the worst accidents in the cylinder business occurred at Gollob Analytical Services in March 1968, when a cylinder there exploded. A customer of a gas company accidently back-filled an oxidizing gas into a pryroforic flammable gas mixture. It didn’t cause an explosion at that time, but during remediation (as the cylinder was being blown down) the mixtures exploded, killing three employees.

Several years later, an employee at another location died when he blew down a cylinder that had been used by a customer to mix insecticide.  

Over the years, there have been a number of near misses reported, and probably some incidents that never made the headlines. One new cause for concern results from people brewing methamphetamines in home laboratories. Some of the manufacturing methods use pure ammonia, a chemical that is used for everything from air-conditioning to farm fertilizer. Since ammonia is often stored in very large storage tanks, perps stealing ammonia often use propane cylinders as the carrying container. Those cylinders are readily available since they are used widely for gas grills and home heating. The problem is created because the valves in those cylinders are made of brass, and brass is a material that should not come in contact with ammonia. The issue has become significant enough that the National Propane Gas Association has set up a web site with information. Everyone interested in the subject should visit the NPGA web site that has pictures and information on the subject – (http://npga.org/i4a/pages/index.cfm?pageid=529)

But the bottom line here is that your employees have to be trained to closely check all incoming, supposedly empty, cylinders. If there is writing on the outside of the cylinder, inscribed with a Sharpie pen, or a tag that indicates some different use has been made of the cylinder – be careful. Also, be suspicious of any cylinder being returned from the petrochemical industry or college and university laboratories. The life you save could be your own.