As a pharma, biopharma or biotech manufacturer, if you care about the safety of your people and environment, one of the most important decisions that you will make will be your choice of pressure vessel.
Often, when starting out with a new project, there is a lot of room for improvement; errors occur, and we learn from them. But pressure vessels can be dangerous if not of the very best quality. So when choosing a pressure vessel, it is important to get things right the first time around. Are you worried? Don’t be – this article is your one-stop solution, a comprehensive guide to making the right decision when it comes to selecting your very first pressure vessel. With this guide in your arsenal of decision-making tools, you’ll have all the information you need to ask your pressure vessel manufacturers the questions that matter – the answers to which can make all the difference between risk and safety, between resource wastage and efficient production.
What is a pressure vessel?
A pressure vessel is any container which is closed, leak-proof, and engineered to operate at pressures much higher than ambient pressure – usually at pressures greater than 15 psig. Ordinarily, pressure vessels hold substances that are in the liquid or gaseous state. They may look like any other process vessels, but these special features, as well as the design features mentioned below, set them apart from your other holding tanks or compounding vessels.
What are the components of a well-designed pressure vessel?
If well-considered and designed by skilled pressure vessel manufacturers, a pressure vessel comprises a shell, internals, nozzles, gaskets, flanges, a skirt, and a baseplate. It should also have ladders and platforms for easy and safe access for use and maintenance. Regardless of their specific application or industry of use, pressure vessels are equipped with mechanisms to remove or introduce heat because temperature and pressure control never occur in isolation; they always go hand-in-hand. Further, given the high pressures they operate at, pressure vessels always have mechanisms in place to be closed completely and securely; any compromise in this department – even a small leak and tiny damage to the vessel – can have disastrous effects on the health and safety of the people in the vicinity of the machine as well as on the efficacy of the machine itself.
How are pressure vessels constructed?
Skilled pressure vessel manufacturers use durable, high-quality metals to produce pressure vessels. The construction material should withstand the harsh temperatures and pressures the machine will be exposed to when in use. The best options for pharma-grade pressure vessels are stainless steel and carbon steel, but in certain situations, aluminium, copper, and sometimes non-metallic substances could also be used. Be certain to ask your pressure vessel manufacturers about their choice of construction material and the rationale behind it.
Categorising pressure vessels
Pressure vessels can be classified on the basis of application, industry, installation, construction, and shape. Apart from application, let’s take a look at the two main ways in which the industry usually categorises these pieces of equipment.
Construction technique
As we’ve mentioned earlier, safety is an absolute non-negotiable when it comes to pressure vessels. To comply with the high demands for safe systems, pressure vessels must be constructed to be entirely leak-proof. There must be no errors or vulnerabilities in design or fabrication. On the one hand, a pressure vessel may have welded construction – this is an approach in which different metal components are welded together; though such construction can only withstand medium pressure, it is definitely more economical than the alternative. The alternative is forged pressure vessels – these are constructed from a single piece of metal, forced into its ultimate shape under high-pressure conditions. This second kind is what you would need if your pressure vessel needs to tolerate extremely high-pressure use cases. A less common technique in the pharma industry, brazing is used for pressure vessel construction in the air conditioning or refrigeration industries.
Shape
The other main method to distinguish pressure vessels is based on their shape. You have cylindrical pressure vessels with flat or dished heads. This shape is the go-to one when making compounding/manufacturing vessels and storage/holding vessels for pharma and biopharma. You also have spherical pressure vessels for use cases that require uniform stress distribution. Not as common in pharma as cylindrical pressure vessels, spherical ones are more likely to be seen in liquified petroleum gas storage and the aerospace industry. Finally, there are also rectangular pressure vessels, but these aren’t commonly found. This rare shape is usually only employed when there are severe space constraints, as it allows for optimal space usage.
Where are pressure vessels used?
Pressure vessel manufacturers find customers in the power, petrochemical, and oil and gas industries. And, of course, in the pharmaceutical industry.
In the pharmaceutical manufacturing industry, boilers, bioreactors, chemical reactors, heat exchangers, distillation columns, and some compounding and holding vessels are designed as pressure vessels. It is important to note, however, that they do not need to be pressure vessels. For example, it’s possible that a holding vessel need only store a substance at atmospheric pressure, in which case it isn’t a pressure vessel. You can find more detailed information about each type here in our guide to different pressure vessels.
What could go wrong?
When it comes to pressure vessels, a lot. This is why you need pressure vessel manufacturers who prioritise safety over all else.
By virtue of holding so much pressure, all pressure vessels bear an inherent risk. These risks are posed to not only the people who operate the systems in your facility but also the environment, the surrounding community, and your facility itself. You can make absolutely no allowance for mistakes – no damages, no cracks, no crevices. Such lapses could result in toxic substances entering your facility. Worse still, they can cause explosions, poisonings, fires, and suffocations. In case of a lapse, the damage will be severe and irreversible. So be it a heat exchanger, a holding vessel, a bioreactor, or a pure steam generator, make sure you choose equipment that meets the highest standards.
Standards
Speaking of standards, it is often difficult to know which particular standards your equipment needs to match up to. It takes a lot of research, and when it comes to pressure vessels, a good place to start is the guidelines of the American Society of Mechanical Engineers, or ASME.
The ASME Boiler and Pressure Vessel Code is regarded as the gold standard for pressure vessel manufacturing. Make sure you refer to Sections II, V, VIII, and IX for standards concerning construction materials, design, engineering, and welding. You can also refer to the EN 13445, API 510, and AD Merkblätter to guide your process as you embark on understanding the construction, piping, inspection, design, repair and maintenance of your pressure vessels. Ultimately, as we’ve said time and again – safety and efficacy are the two guiding principles that should inform all your pressure vessel-related decisions. Without safety mechanisms in place, you might end up harming people’s health and lives rather than helping them. Without efficacious systems, all your investment into your pressure vessels will be for nothing.
