JIS Flanges
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A flange is a method of connecting valves, pipes, pumps or other system equipment to form a piping line. Flanges provide easy access for cleaning, maintenance, inspection or modification. There are many different standards flange being made. These flanges are designed to have standardized dimensions to allow easy interchangeability and functionality.
Flange is made for welding or screw end. Flange connection are made by bolting together two flanges with a gasket in between to provide reliable sealing. Pipe flanges are made in different materials such as carbon steel, stainless steel or brass. |
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Size |
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Material |
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Working Pressure |
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Connection Type |
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JIS Flanges Catalogue
| JIS Flanges.pdf |
What are JIS Flanges
1. What are flanges used for?
The most common material is forged carbon steel and it is available in galvanised and non-galvanised surface coating. The material of a flange is basically set according to the choice of pipe. The most common flange types are:
The most common material is forged carbon steel and it is available in galvanised and non-galvanised surface coating. The material of a flange is basically set according to the choice of pipe. The most common flange types are:
- Weld neck flange
- Slip on flange
- Socket weld flange
- Lap joint flange
- Threaded flange
- Blind flange
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All flanges in each different standard are manufactured into variety of class pressure and it allows the flanges to be capable in taking different working pressure. The common standard includes: .
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Different standard has its own table dimensions and it is not generally interchangeable. Example, ASME 150# will not match with a JIS 10K flange standard. These class pressures have different working pressure and temperature rating according to different material grade.
Flange Standard |
Class Pressure |
American National Standards Institute (ANSI) |
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Deutsches Institut für Normung (DIN) |
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Japanese Industrial Standard (JIS) |
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2. What is slip on flat face flange?
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Slip on flanges are the most popular flange type option of pipe flange designed to insert pipe into the bore hole centre of the flange for welding purposes around both the outer diameter of the pipe. The slip on flange is a simple alternative to a weld on the neck as it does not have a weld bevelled end. Therefore, it allows pipe to be adjusted in length relative to its position of the flange. The bore of the slip on will give an ample amount of space for the matching pipe and it can create some working space for the welder or fabricator to make the connection.
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This flange design is easier to be found in lower pressure assemblies and become less utilized when a high stress service calls for a superior connection to the piping line assembly. The reason is that a slip on style flange will accept a pipe with a fillet weld connection while a weld neck flange will have a reinforced hub at the case which forms a weld bevelled end connection directly to the butt weld piping end connection. The tapered hub allows for a stronger service in mechanical stress environment. Slip on flange has a lower material cost compared to the cost of a weld neck flange.
3. What is the difference between flat face and raised face flange?
Flat face flanges have a contact surface that is same height thickness as the bolting line of the flange. The whole surface is flat and a soft type full face gasket is being used between two flat face flanges. The gasket is typically made from non-metallic material such as Viton or EPDM. The purpose of using a flat face flange is to avoid the bending moment that is put on the flange as the bolts are torque. Some flange material can be easily broken and flat face flange can eliminate this material issue.
The main difference between flat face and raised face flange is that the raised area which surrounds the pipe bore and the flat face flange does not have. A flat face flange cannot be assembled with a raised face flange as this would result in leakage.
Flat face flanges have a contact surface that is same height thickness as the bolting line of the flange. The whole surface is flat and a soft type full face gasket is being used between two flat face flanges. The gasket is typically made from non-metallic material such as Viton or EPDM. The purpose of using a flat face flange is to avoid the bending moment that is put on the flange as the bolts are torque. Some flange material can be easily broken and flat face flange can eliminate this material issue.
The main difference between flat face and raised face flange is that the raised area which surrounds the pipe bore and the flat face flange does not have. A flat face flange cannot be assembled with a raised face flange as this would result in leakage.
4. What is a blind flange?
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A blind flange is a round plate that comes with bolt hole and it has a solid surface to block off a pipeline or to create the end flow. There are commonly used in petrochemical, public services, pipe engineering and water works application. The blind flange is inserted in the middle between two open flanges to block off the liquid flow through a pipeline.
Without the blind flange, it would be challenging to perform maintenance or repairing jobs on a pipeline. As the flow needs to be cut off in the pipeline upon maintenance and the nearest valve might be miles away from the repair area. Therefore, installation of a blind flange is much more cost efficient for a piping line. |
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5. Flange to flange assembly components
- Step 1: Ensure flange faces are cleaned without score marks or debris that could affect the sealing quality. Place the gasket on the flange and ensure the holes are evenly aligned to the other side.
- Step 2: Align the flange and gasket evenly and insert the bolts and washers through the gasket and flange. Place a washer and follow by the nut on each bolt from the other side. Make sure all bolting body is clean and then insert 4 bolt sets at approximately 90-degree apart and finger tighten them. Check and ensure correct alignment of the flange joint and insert the remaining bolt and finger tighten it once alignment is met.
- Step 3: Tighten the nuts and bolts as per the standard tightening sequence. Recommended tightening in four steps and there are 20%, 50%, 75% and 100% of recommended tightening torque.
JIS Flanges Catalogue
| JIS Flanges.pdf |
