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Tips For Selecting Appropriate Flanges for Your Work

Oil and gas plants are massive, complicated settings with thousands of miles of interconnecting pipe. Choosing the right sort of flange for the purpose is critical for any flange or product to work properly. To work effectively, the flange must fit exactly into the pipe joint. A little error in flange selection can have a significant impact on an application, resulting in a costly error.


Factors associated with selecting the suitable flange for the correct application are as follows:

Types of Pipe Flanges:

The design of the flange type may usually be used to identify it. First, determine if the flanges have a socket weld, flat flange, lap joint, threaded bore, welded neck, groove, or tongue flange. The bottoms are then recognized by determining whether they have a flat face, which is entirely flat, or a raised face, which is a little raised area on the face of the flange. All of this information is normally determined by the stamping on the outer diameter of the flange, assuming it hasn’t been painted over. It is critical to retain an archive of your assembly parts for future reference and repair.

Weld neck flanges: –

These flanges are butt-welded to the pipe’s end, likely to result in a flange that can withstand high temperatures and pressures.

Threaded flange: –

It has an internal thread through which a threaded pipe is screwed. This is easily installed, but it is not suitable for high pressure or temperature.

Socket-welded flanges: –

A plain hole with a shoulder at the bottom characterizes these socket welded flanges. The pipe is implanted into the hole and welded into place with a fillet weld along the outside to butt against the shoulder. This is used for low-pressure pipes with small diameters.

Slip-on flanges: –

There seems to be a plain hole on these flanges as well, however, there is no shoulder. Both side of flanges fillet welds are used.

Lapped flanges: –

There are two parts to the flanges: a stubend and a backing flange. The pipe’s end is butt-welded to the subend, which has a small flange with no holes. The backing flange slides over the shaft and has holes for bolting to another flange. This design allows for disassembly in tight spaces.

Blind flanges: –

Blind flanges are a type of blanking plate that is bolted to another pipe flange in order to isolate or terminate a section of piping. Before you select any flanges for your Industrial Piping System always remember particular factors that you need to focus on. Given below are some of the highlighted factors to make note on.

Size of Flanges

The flange size is determined by several factors, including the standard (JIS – Japanese International Standard, ANSI – American National Standards Institute, and DIN – Deutsches Institut für Normung / European), the pressure level required, and the actual overall outside diameter and thickness of the flange. The number of bolt holes, inside diameter, outside diameter, bolt circle, and bolt hole diameter are all variables in determining the total call-out, but the nominal pipe size is usually uniform.

  1. Outside diameter
  2. Nominal bore size
  3. Inner diameter
  4. Bolt circle diameter
  5. Thickness
  6. Pipe size
  7. These dimensional factors may come in handy when updating, maintaining, or updating piping systems.

Bolt Holes

Bolt holes assist in determining flange size and pressure class. Three parameters must be considered: the actual size of the bolt holes, the pitch circle diameter, and the number of bolt holes on the flange. Higher pressure capabilities are frequently associated with stronger and thicker bolts.

Material Of Flanges

It is important to select the appropriate material for a flange. This requires an understanding and use of the parts in a pipe system application. The most commonly used materials include chrome, nickel, carbon steel, duplex steel, stainless steel, and so on. The most common type of pipe flange on the market is forged carbon steel pipe flanges. Flanges made of stainless steel, aluminum, cast iron, and bronze are available as well. Flanges made of specialty metals like chrome-moly, Inconel, and Monel are also available. The material used is determined by the industrial application as well as the piping systems. This ensures that they will be strong and durable in the long run. In most cases, however, the flange is made of the same material as the pipes.

Classification Of Flanges

All flanges are categorized by ASME or ASTM standards into one of several categories. The characteristics of a particular flange type will have a significant impact on how it performs in a variety of industrial settings. Steel pipes come in a wide range of styles and pressure ratings. Metal flanges are rated from 150 to 2500 pounds per square inch. The following are some of the most common classifications used in the petrochemical industry:

  • 150
  • 300
  • 600
  • 900
  • 1500
  • 2500

There are a few important techniques for selecting flanges:

Define your Requirements and Standards

Pipe flanges are available in standard blind, threaded, and weld neck types. Oilfield dimensions are becoming important for functional interchangeability as fittings become standard. All materials have the same standard dimensions. The requirements, on the other hand, are updated regularly, extended, and modified.Flanges can be chosen from a number of industry-defined standards. As a result, flanges aid in product selection depending on standards and applications. It is compatible with the three basic standards previously mentioned, namely JIS – Japanese International Standard, ANSI – American National Standards Institute, and DIN – Deutsches Institut für Normung / European.

Determine Flange Facing

Among the first steps in buying industrial pipe fittings is specifying the face of your flange. The flange face works as the sealing surface. The following are the most common types of flange faces:

  • Full face
  • Flat face
  • Ring-type face
  • Large female and male
  • Lap joint
  • Raised face

Select and Use the Correct Pressure Class

The pressure class denotes the maximum pressure at which the flange can work and sustain itself safely. Each standard has a range of pressure levels specified, ranging from high pressure to low-pressure tolerance. The pressure levels of products attached to flanges must be the same as those of in-service valves and pipes. The current ASME 150# per B16 standard is the most widely used industry pressure class. The dimensions of the flange standard are determined by its pressure class. The pressure class ratings can range from 125 to 900 psi. Within the oil and gas industry, four elements determine the pressure limits of the flange:

  • Sizes of flanges
  • Materials used
  • Both external and internal temperatures
  • Bolt size, number, thickness, and dimensions

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