Flange

Last updated

A flange is a protruded ridge, lip or rim, either external or internal, that serves to increase strength (as the flange of an iron beam such as an I-beam or a T-beam); for easy attachment/transfer of contact force with another object (as the flange on the end of a pipe, steam cylinder, etc., or on the lens mount of a camera); or for stabilizing and guiding the movements of a machine or its parts (as the inside flange of a rail car or tram wheel, which keep the wheels from running off the rails). Flanges are often attached using bolts in the pattern of a bolt circle. The term "flange" is also used for a kind of tool used to form flanges.

Contents

Plumbing or piping

Surrey flange SurreyFlange.JPG
Surrey flange

A flange can also be a plate or ring to form a rim at the end of a pipe when fastened to the pipe (for example, a closet flange). A blind flange is a plate for covering or closing the end of a pipe. A flange joint is a connection of pipes, where the connecting pieces have flanges by which the parts are bolted together.

Although the word 'flange' generally refers to the actual raised rim or lip of a fitting, many flanged plumbing fittings are themselves known as flanges.

Common flanges used in plumbing are the Surrey flange or Danzey flange, York flange, Sussex flange and Essex flange. Surrey and York flanges fit to the top of the hot water tank allowing all the water to be taken without disturbance to the tank. They are often used to ensure an even flow of water to showers. An Essex flange requires a hole to be drilled in the side of the tank.

There is also a Warix flange which is the same as a York flange but the shower output is on the top of the flange and the vent on the side. The York and Warix flange have female adapters so that they fit onto a male tank, whereas the Surrey flange connects to a female tank.

A closet flange provides the mount for a toilet.

Pipe flanges

Piping components can be bolted together between flanges. Flanges are used to connect pipes with each other, to valves, to fittings, and to specialty items such as strainers and pressure vessels. A cover plate can be connected to create a "blind flange". [1] Flanges are joined by bolting, and sealing is often completed with the use of gaskets or other methods. Mechanical means to mitigate effects of leaks, like spray guards or specific spray flanges, may be included. Industries where flammable, volatile, toxic or corrosive substances are being processed have greater need of special protection at flanged connections. Flange guards can provide that added level of protection to ensure safety. [2]

There are many different flange standards to be found worldwide. To allow easy functionality and interchangeability, these are designed to have standardised dimensions. Common world standards include ASA/ASME (USA), PN/DIN (European), BS10 (British/Australian), and JIS/KS (Japanese/Korean). In the USA, the standard is ASME B16.5 (ANSI stopped publishing B16.5 in 1996). ASME B16.5 covers flanges up to 24 inches size and up to pressure rating of Class 2500. Flanges larger than 24 inches are covered in ASME B16.47.

In most cases, standards are interchangeable, as most local standards have been aligned to ISO standards; however, some local standards still differ. For example, an ASME flange will not mate against an ISO flange.[ citation needed ] Further, many of the flanges in each standard are divided into "pressure classes", allowing flanges to be capable of taking different pressure ratings. Again these are not generally interchangeable (e.g. an ASME 150 will not mate with an ASME 300). [3]

These pressure classes also have differing pressure and temperature ratings for different materials. Unique pressure classes for piping can also be developed for a process plant or power generating station; these may be specific to the corporation, engineering procurement and construction (EPC) contractor, or the process plant owner. The ASME pressure classes for flat-face flanges are Class 125 and Class 250. The classes for ring-joint, tongue and groove, and raised-face flanges are Class 150, Class 300, Class 400 (unusual), Class 600, Class 900, Class 1500, and Class 2500. [3]

The flange faces are also made to standardized dimensions and are typically "flat face", "raised face", "tongue and groove", or "ring joint" styles, although other obscure styles are possible.

Flange designs are available as "weld neck", "slip-on", "lap joint", "socket weld", "threaded", and also "blind". [3]

ASME standards (U.S.)

Two ASME type flanges, bolted together on a gas pipeline Flanschverbindung Gasleitung.jpg
Two ASME type flanges, bolted together on a gas pipeline

Pipe flanges that are made to standards called out by ASME B16.5 or ASME B16.47, and MSS SP-44. They are typically made from forged materials and have machined surfaces. ASME B16.5 refers to nominal pipe sizes (NPS) from 12" to 24". B16.47 covers NPSs from 26" to 60". Each specification further delineates flanges into pressure classes: 150, 300, 400, 600, 900, 1500 and 2500 for B16.5, and B16.47 delineates its flanges into pressure classes 75, 150, 300, 400, 600, 900. However these classes do not correspond to maximum pressures in psi. Instead, the maximum pressure depends on the material of the flange and the temperature. For example, the maximum pressure for a Class 150 flange is 285 psi, and for a Class 300 flange it is 740 psi (both are for ASTM a105 carbon steel and temperatures below 100°F).

The gasket type and bolt type are generally specified by the standard(s); however, sometimes the standards refer to the ASME Boiler and Pressure Vessel Code (B&PVC) for details (see ASME Code Section VIII Division 1 – Appendix 2). These flanges are recognized by ASME Pipe Codes such as ASME B31.1 Power Piping, and ASME B31.3 Process Piping.

Materials for flanges are usually under ASME designation: SA-105 (Specification for Carbon Steel Forgings for Piping Applications), SA-266 (Specification for Carbon Steel Forgings for Pressure Vessel Components), or SA-182 (Specification for Forged or Rolled Alloy-Steel Pipe Flanges, Forged Fittings, and Valves and Parts for High-Temperature Service). In addition, there are many "industry standard" flanges that in some circumstance may be used on ASME work.

The product range includes SORF, SOFF, BLRF, BLFF, WNRF (XS, XXS, STD and Schedule 20, 40, 80), WNFF (XS, XXS, STD and Schedule 20, 40, 80), SWRF (XS and STD), SWFF (XS and STD), Threaded RF, Threaded FF and LJ, with sizes from 1/2" to 16". The bolting material used for flange connection is stud bolts mated with two nut (washer when required). In petrochemical industries, ASTM A193 B7 STUD and ASTM A193 B16 stud bolts are used as these have high tensile strength.

European dimensions (EN / DIN)

Most countries in Europe mainly install flanges according to standard DIN EN 1092-1 (forged stainless or steel flanges). Similar to the ASME flange standard, the EN 1092-1 standard has the basic flange forms, such as weld neck flange, blind flange, lapped flange, threaded flange (thread ISO7-1 instead of NPT), weld on collar, pressed collars, and adapter flange such as flange coupling GD press fittings. The different forms of flanges within the EN 1092-1 (European Norm/Euronorm) is indicated within the flange name through the type.

DesignAccording to EN typeAccording to DIN
Weld-neck flangeType 11DIN 2627 – DIN 2638
Blind flangeType 05DIN 2527
Threaded flangeType 12DIN 2558, DIN 2565 – DIN 2569
Flat flangeType 01DIN 2573, DIN 2576
Lapped flangeType 02 and Type 04DIN 2641, DIN 2642, DIN 2655, DIN 2656

Similar to ASME flanges, EN1092-1 steel and stainless flanges, have several different versions of raised or none raised faces. According to the European form the seals are indicated by different form:

Form: types of contact facesDIN EN 1092-1
Without raised faceForm A
Raised face (Rz = 160 mechanical turned)Form B1
Raised race (Rz = 40 mechanical turned)Form B1
Raised face (Rz = 16 mechanical turned)Form B2
Tongue according to DIN2512Form C
Groove according to DIN 2512Form D
Male according to DIN 2513Form E
Female according to DIN 2513Form F
Female according to DIN 2514Form G
Male according to DIN 2514Form H

Other countries

Flanges in the rest of the world are manufactured according to the ISO standards for materials, pressure ratings, etc. to which local standards including DIN, BS, IS, JIS [4] and others, have been aligned.

Compact flanges

As the size of a compact flange increases it becomes relatively increasingly heavy and complex resulting in high procurement, installation and maintenance costs. Large flange diameters in particular are difficult to work with, and inevitably require more space and have a more challenging handling and installation procedure, particularly on remote installations such as oil rigs.

The design of the flange face includes two independent seals. The first seal is created by application of seal seating stress at the flange heel, but it is not straight forward to ensure the function of this seal.

Theoretically, the heel contact will be maintained for pressure values up to 1.8 times the flange rating at room temperature.

Theoretically, the flange also remains in contact along its outer circumference at the flange faces for all allowable load levels that it is designed for.

The main seal is the IX seal ring. The seal ring force is provided by the elastic stored energy in the stressed seal ring. Any heel leakage will give internal pressure acting on the seal ring inside intensifying the sealing action. This however requires the IX ring to be retained in the theoretical location in the ring groove which is difficult to ensure and verify during installation.

The design aims at preventing exposure to oxygen and other corrosive agents. Thus, this prevents corrosion of the flange faces, the stressed length of the bolts and the seal ring. This however depends on the outer dust rim to remain in satisfactory contact and that the inside fluid is not corrosive in case of leaking into the bolt circle void.

Applications of compact flanges

The initial cost of the theoretical higher performance compact flange is inevitably higher than a regular flange due to the closer tolerances and significantly more sophisticated design and installation requirements. By way of example, compact flanges are often used across the following applications: subsea oil and gas or riser, cold work and cryogenics, gas injection, high temperature, and nuclear applications.

Train wheels

Railway wheel flange (left)
Tram wheel flange (right) TreinTramwielprofiel.svg
  • Railway wheel flange (left)
  • Tram wheel flange (right)
Flanged railway wheel Flanged wheel.jpg
Flanged railway wheel

Trains and trams stay on their tracks primarily due to the conical geometry of their wheels. They also have a flange on one side to keep the wheels, and hence the train, running on the rails, when the limits of the geometry based alignment are reached, e.g. due to some emergency or defect.

Vacuum flanges

A vacuum flange is a flange at the end of a tube used to connect vacuum chambers, tubing and vacuum pumps to each other.

Form factor of PDR and CBR flanges. Pdr-cbr-flange.jpg
Form factor of PDR and CBR flanges.

Microwave

In microwave telecommunications, a flange is a type of cable joint which allows different types of waveguide to connect.

Several different microwave RF flange types exist, such as CAR, CBR, OPC, PAR, PBJ, PBR, PDR, UAR, UBR, UDR, icp and UPX.

Ski boots

The extensions at the toe and heel of this ski boot produce flanges used to clip into the ski bindings. Salomon Divine RS CF.JPG
The extensions at the toe and heel of this ski boot produce flanges used to clip into the ski bindings.

Ski boots use flanges at the toe or heel to connect to the binding of the ski. The size and shape for flanges on alpine skiing boots is standardized in ISO 5355. Traditional telemark and cross country boots use the 75 mm Nordic Norm, but the toe flange is informally known as the "duckbill". New cross country bindings eliminate the flange entirely and use a steel bar embedded within the sole instead.

See also

Related Research Articles

<span class="mw-page-title-main">Plumbing</span> Systems for conveying fluids

Plumbing is any system that conveys fluids for a wide range of applications. Plumbing uses pipes, valves, plumbing fixtures, tanks, and other apparatuses to convey fluids. Heating and cooling (HVAC), waste removal, and potable water delivery are among the most common uses for plumbing, but it is not limited to these applications. The word derives from the Latin for lead, plumbum, as the first effective pipes used in the Roman era were lead pipes.

<span class="mw-page-title-main">Gasket</span> Type of mechanical seal

A gasket is a mechanical seal which fills the space between two or more mating surfaces, generally to prevent leakage from or into the joined objects while under compression. It is a deformable material that is used to create a static seal and maintain that seal under various operating conditions in a mechanical assembly.

A gate valve, also known as a sluice valve, is a valve that opens by lifting a barrier (gate) out of the path of the fluid. Gate valves require very little space along the pipe axis and hardly restrict the flow of fluid when the gate is fully opened. The gate faces can be parallel but are most commonly wedge-shaped.

<span class="mw-page-title-main">Pressure vessel</span> Vessel for pressurised gases or liquids

A pressure vessel is a container designed to hold gases or liquids at a pressure substantially different from the ambient pressure.

<span class="mw-page-title-main">Piping</span> System of pipes used to transport fluids

Within industry, piping is a system of pipes used to convey fluids from one location to another. The engineering discipline of piping design studies the efficient transport of fluid.

<span class="mw-page-title-main">National pipe thread</span>

American National Standard Pipe Thread standards, often called national pipe thread standards for short, are U.S. national technical standards for screw threads used on threaded pipes and pipe fittings. They include both tapered and straight thread series for various purposes, including rigidity, pressure-tight sealing, or both. The types are named with a symbol and a full name. Examples of the symbols include NPT, NPS, NPTF, NPSC.

<span class="mw-page-title-main">Compression fitting</span>

A compression fitting is a fitting used in plumbing and electrical conduit systems to join two tubes or thin-walled pipes together. In instances where two pipes made of dissimilar materials are to be joined, the fittings will be made of one or more compatible materials appropriate for the connection. Compression fittings for attaching tubing (piping) commonly have ferrules in them, and are sometimes referred to as flareless fittings. There are also flare fittings that do not require ferrules/olives.

<span class="mw-page-title-main">Nipple (plumbing)</span>

In plumbing and piping, a nipple is a fitting, consisting of a short piece of pipe, usually provided with a male pipe thread at each end, for connecting two other fittings.

<span class="mw-page-title-main">Pipe (fluid conveyance)</span> Tubular section or hollow cylinder

A pipe is a tubular section or hollow cylinder, usually but not necessarily of circular cross-section, used mainly to convey substances which can flow — liquids and gases (fluids), slurries, powders and masses of small solids. It can also be used for structural applications; hollow pipe is far stiffer per unit weight than solid members.

Nominal Pipe Size (NPS) is a North American set of standard sizes for pipes used for high or low pressures and temperatures. "Nominal" refers to pipe in non-specific terms and identifies the diameter of the hole with a non-dimensional number. Specific pipe is identified by pipe diameter and another non-dimensional number for wall thickness referred to as the Schedule. NPS is often incorrectly called National Pipe Size, due to confusion with the American standard for pipe threads, "national pipe straight", which also abbreviates as "NPS". The European and international designation equivalent to NPS is DN, in which sizes are measured in millimetres, see ISO 6708. The term NB is also frequently used interchangeably with DN.

British Standard Pipe (BSP) is a set of technical standards for screw threads that has been adopted internationally for interconnecting and sealing pipes and fittings by mating an external (male) thread with an internal (female) thread. It has been adopted as standard in plumbing and pipe fitting, except in North America, where NPT and related threads are used.

Threaded pipe

A threaded pipe is a pipe with screw-threaded ends for assembly.

A vacuum flange is a flange at the end of a tube used to connect vacuum chambers, tubing and vacuum pumps to each other. Vacuum flanges are used for scientific and industrial applications to allow various pieces of equipment to interact via physical connections and for vacuum maintenance, monitoring, and manipulation from outside a vacuum's chamber. Several flange standards exist with differences in ultimate attainable pressure, size, and ease of attachment.

<span class="mw-page-title-main">Piping and plumbing fitting</span>

A fitting or adapter is used in pipe systems to connect straight sections of pipe or tube, adapt to different sizes or shapes, and for other purposes such as regulating fluid flow. These fittings are used in plumbing to manipulate the conveyance of water, gas, or liquid waste in domestic or commercial environments, within a system of pipes or tubes.

A back-up ring is a rigid ring that holds an elastomeric seal or plastic connection to its designed shape and in its correct place. Back up rings are commonly used with O-rings, lip seals, and as reciprocating shaft seals. They are also used for piping connections joining two different materials - typically one flexible and one rigid.

<span class="mw-page-title-main">Plastic pipework</span> Tubular section or hollow cylinder made of plastic

Plastic pipe is a tubular section, or hollow cylinder, made of plastic. It is usually, but not necessarily, of circular cross-section, used mainly to convey substances which can flow—liquids and gases (fluids), slurries, powders and masses of small solids. It can also be used for structural applications; hollow pipes are far stiffer per unit weight than solid members.

<span class="mw-page-title-main">Ductile iron pipe</span>

Ductile iron pipe is pipe made of ductile cast iron commonly used for potable water transmission and distribution. This type of pipe is a direct development of earlier cast iron pipe, which it has superseded. The ductile iron used to manufacture the pipe is characterized by the spheroidal or nodular nature of the graphite within the iron. Typically, the pipe is manufactured using centrifugal casting in metal or resin lined moulds. Protective internal linings and external coatings are often applied to ductile iron pipes to inhibit corrosion: the standard internal lining is cement mortar and standard external coatings include bonded zinc, asphalt or water-based paint. In highly corrosive environments loose polyethylene sleeving (LPS) to encase the pipe may also be used. Life expectancy of unprotected ductile iron pipes depends on the corrosiveness of soil present and tends to be shorter where soil is highly corrosive. However, a lifespan in excess of 100 years has been estimated for ductile iron pipelines installed using "evolved laying practices", including use of properly installed LPS. Studies of ductile iron pipe's environmental impact have differing findings regarding emissions and energy consumed. Ductile iron pipe manufactured in the United States has been certified as a sustainable product by the Institute for Market Transformation to Sustainability.

ISO 2852Stainless steel clamp pipe couplings for the food industry was an international standard that defines a non-permanent sanitary food-grade piping interconnect method, commonly used in the food processing industry and with dairy farm equipment.

<span class="mw-page-title-main">Parflange F37</span>

The Parflange F37 system is a technology from the hydraulic area of Parker-Hannifin, which allows a non welded flange connection of hydraulic tubes and pipes.

ASME is a non-profit organization that continues to develop and maintains nearly 600 codes and standards in a wide range of disciplines. Some of which includes the Boiler and Pressure Vessel Code (BPVC), Elevators and Escalators, Piping and Pipelines, Bioprocessing Equipment (BPE), Nuclear Facility Applications (NQA), Process Performance Test Codes (PTC), and Valves, Flanges, Fittings and Gaskets (B16).

References

  1. "Piping Flanges – Types of Flanges in Piping Systems". www.piping-world.com.
  2. "Flange Guards Safety Spray Shields For Pipe | Valve Cover & Guard". Indana Steel.
  3. 1 2 3 ASME B16.5
  4. "Slip on Flange | ASME B16.5 Slip on Flange at best price". 21 February 2022.

Further reading