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Guide to Properly Measure Flanges

Flanges are the best and easiest way to connect pipes, pumps, and valves. They come in different types and shapes. Flanges are in high demand and are the most convenient and cost-effective components in the piping system.

Flanges and their Advantages:

Flanges are ring-shaped devices designed to substitute for welding in various piping system components. A flange is integrated into the piping system either by welding or screwing.

Flanges are highly flexible and can be easily fixed or removed if any modification is required. So the industries that require frequent maintenance rely on this piping system component.

While purchasing flanges, make sure they possess high-pressure ratings and a good capacity to tolerate extreme temperatures if your application requires this.

Flange Faces and Its Types:

Before moving on to the different flange types, it will be productive to know about the different flange facings.

Flat face

Raised face

Ring-type joint face

Pipe flanges are made up of materials like stainless steel, cast iron, aluminum, bronze, brass, and even plastic. The most preferred material is the forged carbon steel. Each flange is different and has different characteristics, and so when choosing a flange, always double-check to make sure that it meets the specific requirements.

Flanges are available in different types, and so it is easy to choose according to your specific needs. Most commonly they are blind flanges, slip-on flanges, and welding neck flanges, and less often they are socket welding flanges, threaded flanges, lap joint flanges, and custom. Among these, welding neck flange is preferred in piping systems of a more complex nature.

How to Find Out the Right Flange Dimensions?

It is common knowledge that flanges can join the pipes to other parts of your assembly or vessel, but to get the best out of flanges, you must ensure that the flanges are correctly measured. Only then, the rest of the process can be done smoothly. Finding the apt flange dimensions is the primary and essential step.

A few efforts are required to get the right flange dims. The right measurement is completely dependent on understanding the accurate pressure ratings and the size of the corresponding pipe.

First, to measure the standard pipe flanges, measure the outer diameter of the flange (O.D.). It can be achieved by measuring from the outer edge of the flange to the opposite outer edge and then measuring the flange’s inner diameter from these two outer reference points.

Similarly, while taking flange dimensions, you should consider the flange base thickness too. For this task, you only need to analyze the thickness of the attaching outer rim (the base where the bolt pattern is located).

Calculating the Flanges Weight:

While calculating the weight, it is necessary to understand that the construction of pipe flanges is directly connected to the material grade and the pressure it can handle.

The weight calculation of pipe flanges is based on the model of the flange. Now calculating the flange weight is pretty simple as most of the manufacturers have provisions for this.

Just providing a few details like outside diameter and inside diameter, the thickness of the base, the number of drill holes, the diameter of the holes, and the chamfer can easily help calculate the flange weight in seconds.

Measuring Flange Thickness:

Flange thickness calculation can be achieved through some techniques. In standard flanges, by understanding the design conditions, especially the pressure and temperature of the piping system and the kind of piping material, the thickness can be found.

In this situation, no calculations are required to find the flange dims. All you need is to check the ASME pressure vessel design calculations and determine the ratings that match the design condition. Once you find out the flange rating (class), it is easy to find the standard flange dimensions from the ASME B16.5 table.

Flange Specifications:

Many standard flange specifications are available depending on the variety of industries. Flange specifications indeed vary according to the industries and their applications.

Most of the standard manufacturers offer popular flange specifications like ASME/ANSI flanges, DIN flanges, API flanges, and AWWA flanges. ANSI stands out as the best and most popularly used among the various flange specifications because of its ubiquitous mechanical designs amongst ASME engineers.

ANSI Flange and its Dimensions:

ANSI (or the American National Standards Institute) is the most standard flange specification and the most preferred flange in various industries. The standardized ANSI flange dimensions are 150, 300, 400, 600, 900, 1500, and 2500, in sizes NPS 1/2 through NPS 24. Furthermore, ANSI B16.47 covers pressure classes ranging from 75 to 900.

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