April 23, 2019
As the post heading implies, there are different types of pressure vessel materials, and they are used in different applications. Destined for a variety of fundamentally contrasting usage domains, it's easy enough to alter the geometry of a pressure vessel or to thicken its walls. Along with those function-specific features, though, a tank-like frame must present a steel-hardened backbone, which can flex but never rupture. Is steel, then, really the ideal choice?
Offshore Pressure Vessels
Unlike the dynamic fluid containment units used in chemical plants, there are fewer transient forces to offset on an offshore site. Therefore, the material planning engineer can focus on containment, on storing the recently extracted crude oil or gas. Beyond such utilitarian concerns, the design engineer is more worried about another material compromising threat. Corrosion is the biggest threat. To eliminate that external menace, oxidization resistant carbon steels are used to construct the vessels. Near rustproof alternative alloys are also an option.
Materials For Chemical Containment
It would be hard to list the different chemical classes and the ways in which they can weaken different alloys. Suffice to say, there's an immense range of different chemicals, so a vessel designer must have foreknowledge about a specific compound or medium before a pressure vessel material can be selected. Stainless steel is always a popular option. If a chemical base is too aggressive, a Hastelloy nickel steel substitute, composed of salts-resisting nickel-molybdenum-chromium, plus tungsten, should prevent a corrosive attack. Again, the chemical reagent must be identified before selecting the pressure vessel alloy.
There Are Alternatives To Steel
Even Hastealloy has a steely backbone. As a matter of fact, all large pressure vessels lean towards steel-reinforced alloys. For smaller variants, there are other options. Polymers operate in beer and beverage containment plants as low tensile storage tanks. Glass fibres further improve their pressure handling capabilities, but they're not nearly as strong as a comparable carbon steel vessel. Titanium, a lightweight but expensive metal, has a gift for rejecting the aggressive chemical reactions that occur when metals contact salt water. Unless that lightweight feature is heavily in demand, however, a similarly featured stainless steel will manage just as well.
Nickel steels tend to enter the material selecting equation often. They alloy easily with chromium when a high degree of heat resistance is required to support the alloy's high-pressure retainment attribute. Ultimately, because of the vast number of materials and the equally vast number of applications, a customer should open a line of communication with a pressure vessel vendor. The design and implementation team can't properly proceed without this important information. But, armed with this data, the optimally sourced alloy partners with the correct welding techniques and machining processes to form the perfect construct.
Fusion - Weld Engineering Pty Ltd
ABN 98 068 987619
1865 Frankston Flinders Road,
Hastings, VIC 3915
Ph: (03) 5909 8218
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