flange connection – ZECO Valve

Valve Connection Type and Classification of Flanges

Jerry — Tue, 04 Jan 2022 16:26:14 +0000

What are we talking about when we talk valve connections? Today’s topic is about some common valve connection types, including flange (RF, FF, RTJ), Screw (NPT, BSPT), Weld (Butt Weld, Socket Weld), and some codes and standards for these connections.

Valve Connection Type

Flange Connection

Flange connection type is the easiest connection to be installed or uninstalled from a pipeline. Arguably these are the most commonly used end connections at present.

Raised Face Flange – RF

The most common type used in process plant applications are the Raised Face flanges. This flange is preferred because of its raised gasket surfaces above the bolting circle face. This design allows the use of a wide combination of gasket designs, including flat ring sheet types and metallic composites such as spiral wound and double jacketed types.

Flat Face Flange – FF

The Flat Face – FF flange has a gasket surface that is in the same plane as the bolting circle face. Applications using flat face flanges are frequently those in which the mating flange or flanged fitting is made from a casting (e.g. bronze and iron valves). Additionally, according to ASME B31.1, when connecting flat face cast iron flanges to carbon steel flanges, the raised face on the carbon steel flange must be removed, and a full face gasket is required.

Ring-Type Joint Flange – RTJ

A Ring-Type Joint can also have a raised gasket face with the difference being the ring groove machined in this face. This groove will accommodate a steel ring gasket for flange mating

Screw Connection

Threaded connections are very common. They provide a compact and streamlined connection between the valve and pipe.

NPT – National Pipe Taper Threads

This is a U.S. standard for tapered threads used on threaded pipes and fittings. In contrast to straight threads like those that are found on a bolt, a taper thread will pull tight and therefore make a fluid-tight seal. Pipe tape or pipe compound should be used on the threads to ensure a fluid-tight seal.

BSPT – British Standard Pipe Taper Threads

This standard is similar to NPT, where the threaded portions of the connection are tapered. The only difference is the angle of the thread flanks. The angle from root to crest on BSPT threads is 55° as opposed to 60° for NPT. It is possible for a male NPT to fit into a female BSPT, but due to the difference in the thread angle, a fluid-tight seal will not be made.

BSPP – British Standard Parallel Pipe Threads

This type of thread does NOT form a fluid-tight seal as the tapered threads do. The use of a soft seal is required to do so. These threads will pull the 2 mating parts together, and compress the soft seal between flat surfaces on each component.

Welded End Connection

Welded connections are used where zero leakage is important to the system. This is typically in high-temperature and high-pressure piping systems. It is also common to use welded connections with chemically dangerous fluids. Trained professionals should carry out welded connections. They are a permanent type of connection. There are two main types of welded connections for valves:

Socket Welded Connections

This type of welded connection has a valve diameter larger than the pipe’s diameter, such that the pipe can fit into the valve socket end. The weld is done around the rim of the valve end that is connected to the pipe.

Butt-Welded Connections

In this welded connection, the valve ends and the pipe ends have the same diameter. The connection ends are placed against each other and grooved to create a space for the weld. The weld is done around the rims of the connection. Butt welding is common for smaller pipe sizes.

Classification of Flanges

The new standard flange connection is an important connection for pipeline construction. Using bolts to connect two pipelines, fittings or equipment together is called flange connection, also between these two flanges, you need to add flange gaskets to fasten the connection. Some fittings and equipment which already have flange plates themselves also belong to flange connection.

The new standard flange can be divided into a screw connection flange and welded flange. Low pressure and small diameter situation is suitable for wire flange while welded flange is more often used in high/low pressure and large diameter situation. Flanges with different pressure will have different thicknesses, as well as the diameter and quantity of connecting bolts. Depending on the level of pressure, flange gaskets will also have various materials, such as low-pressure asbestos gaskets, high-pressure asbestos gaskets, metal gaskets, and so on. Available to withstand great pressure, flange connection is easy to use.

The new standard flange connection has a wide application in the industrial pipeline. Within the family, it is not possible to see the flange connection because of the small pipe diameter and low pressure. But if you are in a boiler room or production site, flanged pipes and equipment will be scattered everywhere.

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News – Difference Between Flange Connection, Threaded Connection And Welded Connection | API approved valve manufacturer

Jerry — Thu, 30 Dec 2021 07:24:24 +0000

Valves have various types of connections like threaded, flanged, welded, tri-clamp, double union, and so on. In this article, we will share the details about flanged, threaded, and welded.

Flanged Connection Valve —Looking for a flanged valve?

Flanged valves are easy to install and disassemble, but flanged valves are bulkier and more expensive than threaded valves, so they are suitable for pipe connections of all sizes and pressures. Large-size pipelines usually uses the flanged connection.

Flanged ball valves and flanged butterfly valves are widely used in wastewater treatment, paper and pulp, shipyard, and other applications which require a flanged connection.

What is flanged end valve?

Most flanged end connections adhere to an industry standard. These standards define certain criteria that must be met to facilitate the use of products from various manufacturers.

ANSI is the American National Standards Institute. Together with the ASME (American Society of Mechanical Engineers), they have developed and published a standard for flange connections. That standard is ASME/ANSI B16.5.

There is also a European standard that is similar, but NOT THE SAME. That standard is DIN, which is an acronym for the german translation of “German Institute for Standardization.” The specific standard for pipe flanges is DIN EN 1092-1. This standard is also recognized by ISO (International Standards Organization) under ISO 7005.

SAE is the Society for Automotive Engineers. They have also developed a standard for flange type connections where the flange is separate from the components that it holds together. That standard is SAE J518. This standard is also recognized by ISO under ISO 6162.

Types of Flange Connection

Flat Face (FF)

As the name suggests, flat face flanges feature a flat, even surface combined with a full face gasket that contacts most of the flange surface.

Raised Face (RF)

These flanges feature a small raised section around the bore with an inside bore circle gasket.

Ring Joint Face (RTJ)

Used in high-pressure and high-temperature processes, this face type features a groove in which a metal gasket sits to maintain the seal.

Tongue and Groove (T&G)

These flanges feature matching grooves and raised sections. This aids in installation as the design helps the flanges to self-align and provides a reservoir for gasket adhesive.

Male & Female (M&F)

Similar to tongue and groove flanges, these flanges use a matching pair of grooves and raised sections to secure the gasket. However, unlike tongue and groove flanges, these retain the gasket on the female face, providing more accurate placement and increased gasket material options.

A Look at Flange Connection Dimensions

Apart from the functional design of a flange, flange dimensions are the most likely factor to impact flange choices when designing, maintaining, or updating a piping system.

However, you must consider how the flange interfaces with the pipe and the gaskets in use to ensure proper sizing.

Common considerations include:

Outside diameter: The distance between two opposing edges of the flange face
Thickness: A measure of the thickness of the outer attaching rim
Bolt circle diameter: The distance between opposing bolt holes when measured from center to centre
Pipe size: A designation of the pipe size with which the flange corresponds
Nominal bore size: A measurement of the flange connectors inner diameter

Threaded Connection Valve —Looking for a threaded valve?

The threaded connection is generally used for pipes less than 50mm. If it is larger than 50mm, we would recommend using flanges and other connection methods.

The threaded connection is divided into G, NPT, BSPP, and BSP standards, as well as female and male threads.

Types of Threaded Connection

NPT – National Pipe Thread Tapered

NPT is defined by ANSI/ASME standard B1.20.1.
There are 25 sizes defined from 1/16″ to 24″, (see a chart with sizes and dimensions) however typically valves over 4″ will use flanged connections rather than threaded.

NPT threads are specified using the size in inches followed by “NPT”.

BSPT – British Standard Pipe Taper Threads

This standard is similar to NPT, where the threaded portions of the connection are tapered. The only difference is the angle of the thread flanks. The angle from root to crest on BSPT threads is 55° as opposed to 60° for NPT. A male NPT can fit into a female BSPT, but due to the difference in the thread angle, a fluid tight seal will not be made.

BSPT threads are defined by ISO 7 and/or EN 10226-1, BS 21.

BSPT threads are specified using the letter “R” followed by the size in inches. R stands for “rohr” which is german for the pipe.

BSPP – British Standard Parallel Pipe Threads

This type of thread does NOT form a fluid tight seal as the tapered threads do. The use of a soft seal is required to do so. These threads will pull the 2 mating parts together, and compress the soft seal between flat surfaces on each component.

BSPP threads are defined by ISO 228-1:2000 (Dimensions, tolerances, and designation) and ISO 228-2:1987.

BSPP threads are specified using the letter “G” followed by the size in inches. G stands for “gas”.

The threaded connection is suitable for low-pressure pipelines. Lower price.

Welded Joint Valve —Looking for a welded valve?

Welding connection refers to welding the valve and the pipe together.

Suitable for pipelines that require zero leakage, such as high temperature and high-pressure pipelines. Welding is divided into socket welding and butt welding.

Socket Weld

The valve simply has a socket with an inner diameter that is ever so slightly larger than the pipe’s outer diameter. The pipe is inserted into the socket and is welded around the rim as shown here. Socket weld connections are usually reserved for smaller sizes, typically 2″ and below. They are permanent connections that are reliably leak-free. This example includes “heat sink” fins which help dissipate heat to protect the seals during welding. Valves with this feature are often referred to as “weld-in-place.”

Note: These welds should be performed by a trained professional. Care must be taken to avoid damaging the seats and seals with excessive heat.

Butt Weld

The valve end and the pipe end are of equal diameters. The outer edge of each is chamfered to create a “valley” to be filled with welding material. The two pieces are welded around the rims as shown in the illustration. Butt weld connections are usually reserved for smaller sizes, typically 2″ and below. The example shown here also includes the heat sink fins.

Note: These welds should be performed by a trained professional. Care must be taken to avoid damaging the seats and seals with excessive heat.

PS: Welding requires professionals to operate.

All of the threaded, flanged, and welded valve with ISO5211 mounting standards for electric actuators and pneumatic actuators.

Don’t figure out which connection should use? Contact us and we will help you to choose the suitable one.

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