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3 Essential Factors to Consider During Pressure Vessel Modification

October 4, 2019

The construction of pressure vessels used in the US and Canada are stringently monitored by ASME regulations. These vessels are designed for holding gases, as well as toxic and non-toxic fluids at different pressures and temperatures. They are designed to ensure the safety of users and surroundings. However, that doesn’t assure the longevity of these vessels always. Although these vessels are made using robust materials, still they undergo wear and tear over time. These defects demand immediate repair or replacements, owing to the nature of material stored in these vessels. However, there are certain things to be kept in mind while performing repairs and replacement of the vessel parts and components. This post focuses on three such important factors that you need to consider while performing repair or modification of these vessels.

3 Key Factors to Consider For Cost-Effective Pressure Vessel Modification

Before delving into details of repair and modification, it is important to perform these preliminary steps, which will give you an idea of the nature of repair or modification to be performed.

  1. Inspect the Vessel:It is important to conduct an internal and external inspection of vessels, before deciding on the mode of repair and replacements. This inspection must be conducted by a certified expert. While inspecting they must take into consideration two factors – the type of damage and the factor/factors contributing to the damage. They can refer API 572 (American Petroleum Institute) to evaluate the nature of degradation and deciding on the inspection technique. As every vessel design is different, so is each damage cause, and environment of the application. Hence, the inspector must consider all these parameters while deciding on the right technique of inspection. Pressure vessel inspection may involve thickness measurements, as well as external inspection of ladders, platforms, stairways walkways, foundations and supports, anchor bolts, grounding connections, auxiliary equipment, external metal surfaces, external evidence of corrosion, and so on.
  2. Go for Replacement If needed:Any small physical change in a component can affect the performance of the pressure vessel beyond the scope and also endanger its safety. Features such as pumps, valves, as well as other equipment must be inspected on a regular basis to identify potential damages. Many businesses practice “replace when necessary” vs “replace when needed” program. In the first option, the replacement is done only once the part has undergone 75% wear, whereas the second option allows replacement even if the part has undergone 50% wear and tear.


The above steps will help you make the right decision on repair or modification. However, before proceeding with either, it is important to consider the following:

  1. ASME Code Regulations:Repairing or modification is necessary to ensure longevity, safety, and performance of a vessel. As these vessels are subjected to immense pressure in most applications, they can be dangerous, leading to explosions. For this reason, ensuring their safety is important. When performing the modification, it is important to assure that the vessel layout and characteristics are not changed in any way. The repair involves several processes which may alter the process chemistries such as flow rates, temperatures, fluid phase, and characteristics of the vessel. Although these alterations may suffice your purpose, they may have a profound effect on your pressure vessel in the long run.
  2. Material:Material consideration is an important requirement when it comes to pressure vessel repair or modification. It is important to ensure that the materials – metallic and non-metallic are compatible with the existing materials, and chosen in adherence to ASME guidelines. This will help you ensure the safety of vessels in pressurized environments.
  3. In-Depth Understanding of the Process:Repair or modification of pressure vessels are usually performed in phases. They comprise several steps including fabrication, procurement, inspections, tests, examinations, and so on. Each of these steps requires comprehensive preparations. Along with these preparations, it is important to ensure the safety of the vessel and the person working on it. The fabrication must be performed in adherence to guidelines set by ASME. Leak tests are part of pressure vessel repair and modification procedures. There are several types of leak tests including – pneumatic, hydrostatic, sensitive, and in-service. The choice of the right testing procedure is important. Again, it must be performed by certified personnel.


All the outlined key factors will help the manufacturer to safely repair or modify a pressure vessel. It is important to get these repairs and modifications done by an industry expert like BEPeterson. Being one of the leading pressure vessel fabricators in the USA, BEPeterson has been successfully delivered customized stainless steel pressure vessels and storage tanks. The company has set standards for custom metal fabrication. Being ASME and ISO 900:2015 certified, the company is committed towards quality.

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