How to Choose the Right Size and Shape of Your Stainless Steel Manway


Many industries need solid storage tanks, and a stainless steel manway is a vital part of nearly every tank. But, as it turns out, it is not that difficult to make a mistake and choose the wrong system. Consequences can be significant. In this article, we will explain what to consider while choosing steel manways for tanks.

Understanding the Purpose and Function of a Manway

Whenever a pressure container or a storage tank is used, it needs to have a reliable opening system. This might seem as something uncomplicated, but reality proves otherwise. Depending on a storage unit and its purpose, different manways need to be applied to inspect the interior of this unit. Therefore, the properties of a stainless steel manway must be carefully selected if it is to be useful and most of all – safe. A round manway is a common choice, and good examples of such products can be found here:

Factors to Consider When Selecting the Size of Your Manway

Stainless steel manways for tanks come in many sizes. There are a few important factors to include in your decision-making process before rendering a choice. The purpose of the container is crucial, but clearance diameter must be considered as well. In most industrial projects, a standard diameter is enough. This property is represented by a symbol DN300 that can get as high as DN500. Obviously, there are smaller diameters for pressure manways, but larger ones are also available. They are required in situations when additional inspection window is necessary. Such products can have the clearance diameter as wide as DN1400.

Evaluating the Shape of Your Manway: Round vs. Rectangular

Industrial manways are available in 2 basic shapes. As we mentioned before, round manways are very common. They serve well in most circumstances and can be manufactured in dozens of design patterns containing different variations of locking mechanisms. They are usually placed on the top of the tank, but that is not the rule. Rectangular manways are more suitable for side openings, though. They are less resistant to pressure (0.5-2.5 bar) which makes them a comfortable option for an inspection element used with low-pressure tanks or silos. If you are interested in such solutions, please visit

Common Mistakes to Avoid When Selecting Your Manway

The first mistake refers to clearance diameter. In many projects, it can be too big, but it most definitely shouldn’t be too small. The second mistake is about pressure. A rectangular manway can’t work well in a high-pressure environment. Establishing pressure requirements is therefore important before delivering a decision about a stainless steel manway that needs to be installed on a particular tank.