What are the Different Hazard Levels in Pressure Vessels?

December 11, 2018

Pressure vessels must be assigned one of five possible hazard levels. Just as the AS 43434:2014 standards state, these ratings act as essential warnings. They tell everyone who approaches the fluid-charged enclosures that a potential hazard is contained, and it also classifies that hazard. Hazard Level A is the most dangerous, which means Hazard Level E is the least dangerous pressure containment condition.

Pressure Vessel Warnings: Hazard Level Classifications

Again, Hazard Level A is the most dangerous, Hazard Level B the second most dangerous, and so on, until we reach Hazard Level F. Using the criteria covered in the aforementioned AS standards chapter, those letters are preassigned. But what factors influence and affect the levels. That's something every engineer and technician should know, even if they don't have access to a copy of the guidelines and categories.

• Hazard level A - Large pressure vessels
• Hazard level B - Shop manufactured vessels
• Hazard level C and D - Low and extra-low pressures
• Hazard level E - The hazard is negligible

Determining the Hazard-Impacting Factors

For our purposes, design limitations and installation locations influence the various hazard levels. When these thresholds are crossed, disconcerting risk factor are introduced, and we classify them by adding committee-regulated hazard factors. So, back with our five differently labelled pressure containment units, it's the design pressure that slots into the hazard level determination mechanism. It's followed by fluid temperatures, vessel volume, its location, and the properties of the fluid. Combustible fluids are obviously dangerous. But even oxygen, a gas we breathe in small volumes, becomes extraordinarily hazardous when it's stored in massive volumes.

Addressing Legislation Compliance

Clearly, a fabrication service can only go so far, mostly by calculating the vessel volume and its fabrication characteristics. The pressure, as a maximum and minimum threshold, is also easy enough to calculate, but that's where the work stops. The relevant design criteria also come from the installation site, where the fluid type is known and the storage conditions appraised. Knowing all of the above variables, the hazard levels can then be registered and pushed into service with a full array of warning stickers and labels.

Again, the ruling standards are found in the AS 4343:2014 guidelines. Committee audited, those standards must be adhered to by the fabrication service and the installation engineers, plus the site managers. Stamps and labels are assigned with the levels, plus a certification. To deviate from this procedure is to risk a hefty fine. Worse still, though, poorly followed hazard level procedures risk catastrophic incidents.

Contact Details

Fusion - Weld Engineering Pty Ltd
ABN 98 068 987619

1865 Frankston Flinders Road,
Hastings, VIC 3915

Ph: (03) 5909 8218

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