Helium shortages are making the headlines more often these days. Much of the concern revolves around helium shortages for party planners and their increasingly expensive balloon releases. But the headlines should really shout about the threats a helium shortage will be to our industries including shipbuilding.
Helium is the second lightest of all the elements, only hydrogen is lighter. Our galaxy and the rest of the observable universe is composed of almost 25% helium by mass. It is an abundant element produced by the atomic decay of heavier matter within stars like the sun.
What Helium Shortage?
So why are we talking about a helium shortage when it is of one of the universe’s most common substances?
In our earth’s atmosphere helium accounts for only 0.00052% of the total gas volume. That figure has decreased steadily since the formation of our planet because helium is able to escape into space faster than it is produced within the earth. Extraction of helium from the air is possible by distillation, much like petroleum fractions are separated, but that is an energy intensive and therefore expensive process.
Luckily there are greater concentrations on the planet. Natural gas pockets can contain up to 7% percent helium by volume and are extracted as the gas is refined. Helium occurs in natural gas because of the atomic decay of radioactive elements in the earth’s crust.
The United States has one of the largest reserves of helium in the world. It is stored underground in natural salt domes beneath the bedrock of the Great Plains region.
In 1996 congress decided to phase out the reserve by selling the billion cubic meters of stored gas to relive the 1.4 billion dollar debt of the reserve. A government study in 2000 found that there would be a helium surplus for the foreseeable future. The gas storage area is expected to be empty by 2015.
Slowing the Helium Shortage by Raising Prices
Since the report in 2000 there has been a huge increase in helium use. Medical, aerospace, and electronics industries are major users of the resource. Welding, mostly of aluminum alloys, makes up about 20% of the total use annually.
Shipbuilders and designers are using aluminum in more applications in order to reduce weight and increase speed and efficiency. Improved coatings are making aluminum the material of choice for high performance, low maintenance craft. The new USCG Response Boat Medium and one design of the US Navy Littoral Combat Ship both use significant amounts of welded aluminum construction.
Working with thin financial margins is nothing new for ship builders but a sudden rise in shielding gas prices could make some contracts less profitable or worse, profitless.
Are There Other Options in Case of a Helium Shortage?
Any inert gas can be used to shield molten metal during the welding process. Most welders are familiar with the mixed gasses used to limit oxidation of the weld bead; carbon dioxide, nitrogen, and argon are all commonly used in electric welding processes. Helium and helium mixtures are used in tungsten inert gas welding, or TIG, and for welding some aluminum alloys.
Helium replacements can be used for most aluminum construction and metallurgists will find better solutions as necessity dictates. But between now and then certain situations will need to be addressed.
Certain aluminum alloys are designed to be welded with helium as part of the shielding mixture.
The common name for Aluminum alloy 5083 is Marine Aluminum Alloy which is traditionally shielded with a helium-argon mixture. The introduction of the stronger 5383 alloy in 1995 promised increased strength and lower weight with similar fabrication procedures. The high performance 5059 alloy was introduced in 1999 and remains the strongest aluminum alloy for marine construction.
Each of these alloys can be welded with pure argon shielding in thinner material sizes. The two newer alloys, which are commonly used today, benefit from using a mixture of 75% helium and 25% argon as a shielding gas when joining thicker sections of material. The helium in the mixture allows more heat to be held near the weld bead and reduces the amount of heat dissipated into the surrounding material which increases the integrity of the joint.
Will There be New Specifications in the Age of Helium Shortages?
When shipbuilder bids a job they are building to a specification; design criteria includes materials, procedures, and processes including specific welding techniques. Welding processes are determined by the certifying organization’s guidelines. Each organization could have different requirements for joining the same materials. For example; the USCG might have a different shielding gas requirement than the ABS standard when producing the same part.
A builder cannot simply replace helium-argon with pure argon shielding gas and be adherent to the terms of the specification and contract. Each element of a vessel’s design is conditional to the assumed strength of the underlying elements.
Certifying Bodies Need to Address the Helium Shortages
It is time for certifying bodies to begin the modification of aluminum alloy welding standards. There will be a significant amount of time between action and adoption. New processes must be tested and retested to assure excellent results without the use of helium in fabrication.
The shipbuilding industry does not need another issue to overcome. There are too many other things for builders to be concerned about like fuel efficiency and emissions. Helium shortages and the problems they cause are easily solved compared to other difficulties in the maritime industry. We can have strong, well-built ships that are efficient and innovative without the use of helium if we make changes before the problem becomes more serious.