Spectacle Blind Flange

Spectacle Blind Flange

A Spectacle Blind Flange is a pressure-retaining plate with one solid end and one open end connected with a web or tie bar.

  • Size: 1/2" to 60", DN 12mm to DN 1500mm
  • Pressure class: Class 150 to Class 2,500, PN 2.5 to PN 250
  • Facing: RF / RTJ

A spectacle flange is a specialty flange made of two metal discs attached in the middle by a small section of steel. Spectable flanges get their name because they look like a pair of reading glasses, or spectacles. Spectacle flanges, also known as spectacle blind flanges, are most commonly used on piping systems that need to be separated regularly or where the flow through the systems is regularly stopped. One end of the spectacle flange is solid, while the other end has a hole in the center. The spectacle flange can be rotated to place either the solid or hollow end within the pipe system, thereby opening or closing the flow.

Spectacle Blind Flange
Spectacle Blind Flange
Spectacle Blind Flange

Advantages of Spectacle Flanges

For pipe Flanges-regularly seperated for isolation, maintenance or reasons, a spectacle extrudes Solution. Typically, spec blinds was mounted in the open position so-your flow pipe operates and is normally. Blinds is mounted onto one of the $number so is need to isolate a, it ' s easy!

Spectacle blind flange

Dimensions of spectacle blinds according to ASME B16.48

Flange spades and ring spacers, as separate products, are used when the rotation of a spectacle blind would be difficult due to space constraints. ASME B16.48 covers the dimensions and specifications of these isolation devices.

  1. Spectacle blind
  2. Flanges
  3. Gaskets
  4. Stud bolts

Spectacle blind types

There are three types of spectacle blinds:

Flat face spectacle blind (FF)

Flat face spectacle blind (FF)

similar to a flat face flange, the surface of the disc is flat (suited for flat face gaskets, for low-pressure applications).

Raised face spectacle blind

Raised face spectacle blind (RF)

likewise raised face flanges, there is an additional thickness on the surface of the disc. This type fits semi-metallic gaskets, as the spiral wound type.

Ring joint face spectacle blind

Ring joint face spectacle blind (RTJ)

a groove is inscribed on the surface of the disc. This type is used in conjunction with ring joint gaskets.

Flange spade vs Spectacle blinds

A spectacle blind combines a flange spade and a ring spacer in a single device (this is the reason why flange spades are called “single-blinds” or “blanks”). The difference is that spectacle blinds may need some space to be rotated, and this space is not always available due to the routing of the piping system. This is when two separate devices are used, as they do not require rotation to be installed.

Spades, ring spacers, and spectacle blinds are available in multiple sizes (from 1/2 inch to 24 inches, and pressure rating from 150 to 2500#) and material grades (the same available for standard flanges) depending on the fluid conveyed by the pipeline.

The difference between spades/ring spacers and spectacle blinds is shown in the image:

Flat face spectacle blind (FF)

Flange spade vs Spectacle blinds:

A spectacle blind combines a flange spade and a ring spacer in a single device (this is the reason why flange spades are called “single-blinds” or “blanks”). The difference is that spectacle blinds may need some space to be rotated, and this space is not always available due to the routing of the piping system. This is when two separate devices are used, as they do not require rotation to be installed.

Spades, ring spacers, and spectacle blinds are available in multiple sizes (from 1/2 inch to 24 inches, and pressure rating from 150 to 2500#) and material grades (the same available for standard flanges) depending on the fluid conveyed by the pipeline.

Ring spacer

Ring spacers are bored to the matching pipe id and are the same thickness as the “single blind” that it replaces. When removing a “single blind”, either the flange and associated piping must be pulled together to seal the line, or a “ring spacer” must be installed to fill the gap. Thick single blinds or rigid piping systems normally require ring spacers.

Single/ line blind or blank

A positive shut-off device normally installed adjacent to, or in conjunction with, a valve. Their purpose is to prevent accidental flow through a pipeline to a vessel. With the exception of cast iron, plastic, or fiberglass services, they are not drilled with bolt holes, but fit inside the bolt circle of mating flanges. Pipeline blinds or blanks are not the same as bolting blind flanges. Single blinds use standard gaskets.

A combination of a “single blind’ and a “ring spacer” can be fabricated for field convenience as a single unit. Weight consideration and the associated difficulty of handling heavy pieces in the field are a primary consideration in specifying a “spectacle blind” or a combination of blinds. Spectacle blinds are meant to be rotated to change blind/spacer orientation.

Spectacle blind

A spec blind is a combination of a ring spacer and single blind. They are usually permanently installed in a piping system and rotated as needed.

Test blank

A test blank is specially designed blank used for hydrostatic or other incompressible fluid testing purposes only. Their advantage is cost and weight savings since higher allowable stress values (or lower safety factors) are used in their design.

Vapor blind

Similar to a “single blind”, but thinner, normally 1/8″ (3mm) to 5/16″ (8mm) thick. These are positive sealing devices intended to prevent accidental flow or leakage of vapors into a pipeline or vessel, usually while the system is in service.

One end of the blind will have an opening to allow flow through the pipe during operation and the other end is solid to block flow during maintenance.

Spec Blind – line open

Line open

Spec Blind – line close

Line close

Spectacle blind datasheets

Standards

Materials

Pipe flanges are manufactured in all the different materials like stainless steel, cast iron, aluminium, brass, bronze, plastic etc. but the most used material is forged carbon steel and have machined surfaces.

Flanges are welded to pipe and equipment nozzle. Accordingly, it is manufactured from the following materials;

The list of materials used in manufacturing is covered in ASME B16.5 & B16.47.

Commonly used Forged material grads are

Frequently used astm grades

Material Fittings Flanges Valves Bolts & Nuts
Carbon Steel A234 Gr WPA A105 A216 Gr WCB A193 Gr B7
A194 Gr 2H
A234 Gr WPB A105 A216 Gr WCB
A234 Gr WPC A105 A216 Gr WCB
Carbon Steel
Alloy
High-Temp
A234 Gr WP1 A182 Gr F1 A217 Gr WC1 A193 Gr B7
A194 Gr 2H
A234 Gr WP11 A182 Gr F11 A217 Gr WC6
A234 Gr WP12 A182 Gr F12 A217 Gr WC6
A234 Gr WP22 A182 Gr F22 A217 Gr WC9
A234 Gr WP5 A182 Gr F5 A217 Gr C5
A234 Gr WP9 A182 Gr F9 A217 Gr C12
Carbon Steel
Alloy Low-Temp
A420 Gr WPL6 A350 Gr LF2 A352 Gr LCB A320 Gr L7
A194 Gr 7
A420 Gr WPL3 A350 Gr LF3 A352 Gr LC3
Austenitic Stainless Steel A403 Gr WP304 A182 Gr F304 A182 Gr F304 A193 Gr B8
A194 Gr 8
A403 Gr WP316 A182 Gr F316 A182 Gr F316
A403 Gr WP321 A182 Gr F321 A182 Gr F321
A403 Gr WP347 A182 Gr F347 A182 Gr F347

ASTM standards define the specific manufacturing process of the material and determine the exact chemical composition of pipes, fittings and flanges, through percentages of the permitted quantities of carbon, magnesium, nickel, etc., and are indicated by "Grade".

The usual materials of flanges include stainless steel, carbon steel, aluminum and plastic. The choice of the material largely depends on the purpose of the flange. For example, stainless steel is more durable and is necessary for heavy use. On the other hand, plastic is more feasible for use in the home because of its reasonable price and easy installation. The materials used for flanges are under the designation of the American Society of Mechanical Engineers.

Flange materials acc. to ASTM

The most common materials for pipe flanges (forged grades) are: ASTM A105 (carbon steel high temperature to match A53/A106/API 5L pipes), A350 Grades LF1/2/3 (carbon steel low temperature to match A333 pipes), A694 Grades F42 to F80 (high yield carbon steel to match API 5L pipe grades), ASTM A182 Grades F5 to F91 (alloy steel flanges to match A335 pipes), A182 Grade F304/316 (stainless steel flanges to match A312 SS pipes), A182 Gr. F44/F51/F53/F55 (duplex and super duplex to match A790/A928 pipes) and various nickel alloy grades (Inconel, Incoloy, Hastelloy, Monel).

The material qualities for these flanges are defined in the ASTM standards.

What are ASTM Grades?

For example, a carbon steel pipe can be identified with Grade A or B, a stainless-steel pipe with Grade TP304 or Grade TP321, a carbon steel fitting with Grade WPB etc.

Standard

Pipe Flange Standards mainly include three systems in the world, ANSI/ASME flange system(American), DIN flange system(European system), JIS flange system, other system made according to this three systems, like GB flange standard, which mainly made according to ANSI/ASME and DIN flange standard, Duwa Piping supplies those flanges with top quality and soonest delivery time.

ASME standards

ASTM standards

AWWA standards

ISO standards

MSS standards

Application of flanges

Applications

A flange is a method of connecting pipes, valves, pumps, and other equipment to form a piping system. It also provides easy access for cleaning, inspection, or modification.

When a piping joint requires to be dismantled, flanges are being used. These are primarily used on equipment, valves, and specialty items. Breakout flanges are provided at predetermined intervals in certain pipelines where maintenance is a regular occurrence. The flanges, gaskets, and bolting make up a flanged joint, which is made up of three separate but interconnected components. To achieve a leak-proof joint, special controls are required in the selection and application of all of these elements.

Here are the details of Flanges about their advantages and their applications.

Advantages of Flanges

Pipes, valves, pumps, and other parts are connected with flanges to form a piping system. Generally, flanges are welded or screwed together. The use of flanges makes pipe system maintenance and repair a breeze. Instead of taking the entire pipe for inspection, a small section of the pipe can be carefully investigated to use a flange to locate the fault.

The following are the five most important benefits of The following are the five most important benefits of flanges:

  • Easy assembly in tight spaces where wrenches may not have clearance if traditional flange fittings are used. With moderate torque, they’re easier to put together.
  • In hard-to-reach areas where flexibility is required, adapters in the hose line, pipe, or tube can be removed.
  • Pipe connections, tubes, or large hose links with high pressure, vibration, or shock pressures that could damage traditional large hydraulic fittings more easily.
  • In rigid lines such as metal tubes or continuous pipes, making connections allows for easy maintenance.
  • In demanding hydraulic applications, reduce the chance of components becoming loose.

A flange is a method of connecting pipes, valves, pumps, and other equipment to form a piping system. It also provides easy access for cleaning, inspection, or modification. Flanges are usually welded or screwed.

In many applications, engineers need to find a way to close off a chamber or cylinder in a very secure fashion, usually because the substance inside must differ from the substance outside in composition or pressure.

They do this by fastening two pieces of metal or other material together with a circle of bolts on a lip. This “lip” is a flange.

Plumbing

You can connect two sections of metal piping by soldering or welding them together, but pipes connected in this way are very susceptible to bursting at high pressures. A way of connecting two sections of pipe more securely is by having flanged ends that you can connect with bolts. This way, even if gases or liquids build up to high pressures inside the pipe, it will often hold with no problem.

Mechanics

In order to connect two sections of a large, enclosed area, it is often best to used flanges and bolts. An example of this is the connection between the engine and the transmission in an automobile. In this case, both the engine and the transmission contain a number of moving parts that can easily get damaged if they get dust or other small objects inside of them. By connecting the outer casings of the engine and transmission in this way, engineers protect the inner workings of both.

Electronics

Flanges have a specific purpose in cameras and other electronic devices. Though flanges in such items do not usually have to sustain high pressures, they do have to hold tight so they can keep out harmful particles. These flanges are usually found connecting two different materials, such as the glass of a lens and the rest of the body of the camera.

FAQ FAQ

The most frequently asked questions regarding flanges and flange fittings have to do with how flanges fit on specific steel tube and steel pipe ends.

How flanges operate?

Flange process

Flanges have flat or flush surfaces that are vertical to the pipe to which they are attached. The attachment process involves mechanically joining two or more faces using bolts, adhesives, collars, or welds. Due to the attachment requirements, a flange must fit the equipment or pipe that it’s designed. That’s why it’s necessary to check all the possible specifications and dimensions to ascertain that it’s of the right size, type, and material.

What are the three parts of a flanged connection?

Pipe flanges, gaskets, and bolts are the three parts that comprise a flanged connection. Gaskets and bolts are typically made of the same flange materials or a material approved for the pipe components. Each component comes in various materials that suit specific applications and must be matched correctly for proper functioning. The gaskets come in two conventional types: full-face gaskets and ring gaskets. Full-face gaskets have the bolt holes visible and pair up with raised-face gaskets. Ring gaskets tend to be smaller rings minus the bolt holes and pair up with flat-faced flanges. Securing the flange components requires matching the surfaces evenly and plumb, adjusting as needed for a uniform fit. Once all surfaces match, bring the flanges together and secure at least two of the bolts. Refine the alignment, so the remaining bolt holes match and their corresponding bolts are tightly secured.

How do I properly size a flange for pipe use?

Properly sizing a flange for pipe use depends not only on the type of flange but its compatible piping. The pipe must slip into the flange’s inside diameter easily and securely, and the outside diameter should cover wall holes. Once you determine the specific flange type and material you need for the job, you’ll need to take several measurements. The four measurements you’ll need are the inside diameter, outside diameter, bolt hole count, and bolt hole center. You’ll need to align each of these measurements from opposing bolt holes to get the most accurate readings. Take all measurements from edge to edge and try to get as precise as possible to match the correct product. Round up bolt diameter to the next half or whole step since bolts measure half or whole inches. Once you have all four measurements, check them against the manufacturer’s table to find the correct flange. Most manufacturers list these specifications on their websites for easy reference.

Flange Inspection

Before dispatching from manufacture each flange is inspected to ensure quality. During an inspection you have to check the following;

ASME B16.5 and B16.47 standards cover permissible tolerances for inspection.

Flange material standards

Flanges are used to connect pipes or other equipment components in various industries, and they come in a variety of materials and sizes. Flange material standards are developed by standard-setting organizations and describe the properties and characteristics of different materials that can be used to make flanges. Some examples of commonly used flange material standards include:

  1. ASTM A105: This standard covers forged carbon steel piping components, including flanges, that are suitable for use in high-pressure applications.
  2. ASTM A182: This standard covers forged or rolled alloy steel pipe flanges, forged fittings, and valves and parts intended for high-temperature service.
  3. ANSI B16.5: This standard specifies the dimensions, tolerances, and markings for steel pipe flanges and flanged fittings.
  4. DIN 2632-2638: This standard defines the dimensions and tolerances for flanges made from steel, including carbon steel, stainless steel, and other alloys.
  5. ASME B16.47: This standard covers large diameter steel flanges, typically used in high-pressure applications where larger bore sizes are needed.
  6. BS 4504: This British standard covers circular flanges for pipes, valves, and fittings, with nominal sizes ranging from 15 to 600 mm.

The choice of flange material standard will depend on various factors such as the application, the environment, the fluid being transported, and the required performance characteristics. For example, high-pressure applications may require flanges made from materials with high strength and durability, while corrosive environments may require flanges made from materials with good resistance to corrosion.

Flanged connection

Flanged connection

There are many ways to connect flanges, including threading, welding or bolting. The threaded flange is best for low pressure or smaller pipelines because it can maintain its seal. When your pipeline is larger or high pressure, then the welded flange is preferable. A boiler room is one place where welded blind flanges might be used, due to the high pressure involved.

Flanged joints: flanges, bolts and nuts and gaskets

A flange is a external rib at the end of pipes, valves and other flow devices to assemble them.

Dimensions of the flanges are up to specific Standards : DIN, ANSI, AS, BS, JIS

A flanged connection requires two flanges (the “main” and the “companion”), a set of bolts and nuts (whose number depends on the flange diameter and class) and two sealing gaskets. Flanged connections have to be executed and supervised by trained personnel, as the quality of the joint has a critical impact on the performance of the piping system / pipeline (the standard TSE – TS EN 1591 Part 1-4, “Flanges and their joints”, defines a number of requirements for the execution of proper flanged connections). Whereas all elements of the joint are critical, experience shows most leaks are originated by the improper installation of the sealing elements, i.e. the gaskets.

The typical pipe to flange connections are welded or threaded. Welded flanges are used for pipelines and piping systems with high pressures and temperatures, and with diameters above 2 inches.

Threaded connections are instead used for installations of smaller diameter and not subject to severe mechanical forces such as expansion, vibration, contraction, oscillation (forces that would crack the threaded joint). In all these critical cases, butt weld connections are recommended.

Delivery

Steel flanges must be packed with seaworthy packing method then delivery to customers, usually the packing way include wooden box, wooden pallet, iron & steel cage, iron & steel pallet etc.

Flange Marking

Flange Marking

Flange markings are governed by ANSI ASME codes. Flange marking includes;

  • Manufacturer logo
  • ASTM material code
  • Material Grade
  • Service rating (Pressure-temperature Class))
  • Size
  • Thickness (Schedule)
  • Heat No
  • Special marking if any QT (Quenched and tempered) or W (Repair by welding)

PMI-raw material inspection

Flange raw material PMI
Flange raw material PMI
Flange raw material PMI

Size inspection

ASME B16.5 and B16.47 standards cover permissible tolerances for inspection.

Flange size inspection
Flange size inspection
Flange size inspection
Flange size inspection
Flange size inspection
Flange size inspection

Packing

Because of the normal wooden boxes or wooden pallets have to do fumigation treatment, we usually use plywood pallet or plywood case or box to pack steel flanges without fumigation treatment.

Flange size inspection
Flange size inspection
Flange size inspection
Flange size inspection
Flange size inspection
Flange size inspection

【H】 Ceramic lined pipe

Ceramic lined pipe is made through self-propagating high-temperature synthesis (SHS) technique.

【H】 Cast basalt lined steel pipe

Cast basalt lined steel pipe is composed by lined with cast basalt pipe, outside steel pipe and cement mortar filling between the two layers.

【H】 Ceramic Tile Lined Pipes

Ceramic tile lined pipes have very uniform coating of specially formulated ceramic material that is affixed to the inner of the pipe.

【H】 Rare earth alloy wear-resistant pipe

The material of the rare earth alloy wear-resistant pipe is ZG40CrMnMoNiSiRe, which is also the grade of rare earth alloy steel.

【H】 Tubes Erosion Shields

Tubes Erosion Shields are used to protect boiler tubing from the highly erosive effects of high temperatures and pressures thereby greatly extending tube life.

【H】 ASTM A213 T91 Alloy Tube

The ASTM A213 T91 seamless tubes are primarily used for boiler, superheater, and heat-exchanger.