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Rubber/elastomer flexible connectors have been specified and used for many years by consulting engineers, mechanical contractors, pressure vessel designers, plant engineers and turn-key construction firms. They are installed to accommodate movement in piping runs, protect piping from expansion and contraction.

Rubber/elastomer flexible connectors provide efficient but economic ways to accommodate pressure loads, relieve movement stress, reduce noise, isolate vibration, compensate for misalignment after plants go on stream, and prolong life of motive equipment. Special built-in features will also eliminate electrolysis, counter expansion and contraction against start up surge forces.


Tozen rubber/elastomer flexible connectors are widely used in piping and pumping application in the following industries:

Suction and delivery pumping lines for air-conditioning, ventilation system and chilled water installation.

Cooling tower and fan coil unit piping lines.

Fire fighting and sanitary system.

Pollution control system for sewerage and water treatment.

Piping systems in general factories.

Power generation plan, marine cooling system, ballast lines, pulp and paper industry, etc.

Tozen Group has manufactured elastomer flexible connectors for more than 25 years. Producing rubber/elastomer connectors is our real core business. Most of Tozen rubber flexible connectors are manufactured with multiple plies of nylon tire cord fabric and natural or synthetic rubber under our special molding rocess. The available sizes range from the smallest 3/4"(20mm up to 80" 2000mm) in diameters. Available working pressures are from full vacuum up to as high as 40 bar. Inquiries of customized elastomer connectors for specific applications are welcomed.


Product Size (mm) Length(mm) AllowableMovement& Installation Tolerance
Tozenflex (Flange type) 32~400 150~200 see catalog
Twinflex (Flange type) 32~350 175~325 see catalog 
Twinflex 20 (Flange type) 150~300 175~200 see catalog
Twinflex (Screwed Type) 15~50 120~175 see catalog

Handling Manual for Rubber Joint(ref: KZ1-P-E-810d) 

1. Noted of Use:

1) Please check existence of damage on the body before use. If any damages are found out especially on the packing area,inner rubber,etc. do not use the products

2) Please use the products after checking max.working pressure and tempature to be within the working conditions.

3) The products might be damaged by impropre operation like complete shut-off operation,etc. Please check the valve position of 'Open-Close securely when in operation.


2. Noted of Stroage:

1) Pay attention to protect the products from damage during transportation and storage. If damaged,do not use the product.

2) In case of stroage for a long time, avoid the direct rays of the sun and store the products in the cool and dark place.

3) Do not leave the products in the place in more than 40 deg C and excessive moisture for a long time.

4) Protect the products from the fire and heat.

5) Do not lead to the products.


3) Notes of Installation:

1) For the installation of the joints to the pump, refer to the right illustration and install.  When the check valve is installed before the joints from the pump, there is a possibility of some trouble occurrence due to accumulation of weariness by water head pressure always received and receipt of direct water hammer occurs when the pump starts and stops.


2) Install the joints within allowable movements of elongation, compression, eccentricity, angular movement, etc.


3) When the joints are in displacement, note for the joints not to touch the structure and equipment (especially sharp edges) near the installation.

4) Take measurement and make centering correctly not to add unnecessary outer force (compression, tension, torsion, etc.) when connecting the joints to the pipes.

5) When welding or cutting the pipes nearby after installation, protect the joints with a cover like our SPARK GUARD from sparks.  In case of the possibility of heat transmission, take some countermeasure like taking the joints off from the pipe, etc.


6) When installation to the outdoor pipes, make lagging to the joints to prevent the joints body aging.

4) Notes of Connection :

Flange Type Connection

 1) For the rubber flexible joints, the packing face of the joints might be damaged depending on the counter flange shape.

Check the shape of the counter flange with the followings.

The connection to welding neck flanges (comparatively high pressure flange) is ideal because inner diameter of rubber body and counter flange is almost same and pressure force to the packing is enough.
In case of tongue and groove type flanges, do not use them because they have a fault which the packing is damaged easily due to small contact area with a projection and rubber packing sheet and so the unit area load getting bigger.
  In case of slip on counter flanges, it is required for the part of arrow mark to be smoothed or asbestos packing, etc. are required to be used together because the packing will be damaged even though theinner diametre of pipe end is the same as rubber body and if the edge is not smoothed.


2) Fix the installation bolts from the joint body side and tighten the nuts at the counter pipe side. It is more safety for the spring washers to be set to prevent looseness of the bolts. In case of the fully threaded bolt, note of the bolt edge not to protrude extraordinary the joint body side.

3) Tighten up the installation bolts in even in the diagonal order.  Refer to the following table of the space after tightening of the bolts for each joint.  The abnormal installation like uneven bolts tightening, etc. will be a factor of damage of the joints.



Nominal S = Space after tightening of the bolts (mm)
Diameter(mm) Tozenflex Twinflex Dynaflex 10flex Oflex-H
32A~ 80A 1~2 1~2 1~2 1~2 1~2
100A 1~2 1~2 1~2 0.5~1.5 1~2
125A 1~2 1~2 2~3 1~2 1~2
150A 1~2 1~2 2~3 0~1 1~2
200A 2~3 2~3 2~3 0~1 2~3
250A 2~3 2~3 2~3 1~2 2~3
300A 2~3 2~3 2~3 1~2 2~3
350A 2~3 2~3.5 - - -
400A 2~3 - - - -

* In case the counter flange is FF type 

4) When the pump operation after the joint installation, the installation bolts are possible to loosen due to the pump vibration. In this case, tighten the bolts slightly again in even in the diagonal order.


(Screw Type of Tozenflex and Twinflex)

1) Remove the installation bolts and take off Flange-A and Socket from the joint body. flexible13
2) Set Flange-A to the counter pipe and check the correct direction of Flange-A. flexible14
3) Check smoothness without damage on the thread part of the counter pipe. flexible15
4) Wind a sealing tape (or other sealing material) the thread part of the counter pipe and tighten up Socket by hand up to certain pitch as much as possible, then set a wrench to the edge of Socket to tighten up well also setting a wrench to the counter pipe. flexible16

5) Fix the installation bolts from the joint side and tighten up the nuts from the counter pipe side.

6) Tighten up the bolts in even in the diagonal order avoiding one side tightening. For the space after tightening of the bolts, refer to the following illustration.


7) For the opposite side, set also the same manner as the above 2)-6)

8) When the pump operation after the joint installation, the installation bolts are possible to loosen due to the pump vibration. In this case, tighten up the bolts slightly again in even in the diagonal order.

5. Noted of Pipe fixing:

There is reaction force from rubber joints due to the load of the internal pressure,so during the installation of rubber joints,please use the metal fittings to fix the pipe tightly to assure the products work efficiently.



Twinflex is twin sphere rubber connectors. Twinflex is made of neoprene and available from size 15mm to 300mm. For screwed end connection, available sizes are 15mm to 50mm and designed for 10 bar working pressure. For flanged end connections, working pressure shall be 20 bars for size 32mm to 150mm, and 16 bars for size 200mm to 300mm. FCD ANSI 150 and JIS10K floating flanges are standard connectors to Twinflex. Other materials and drilling standards of floating flanges can be supplied upon request. In general, Twinflex provide higher vibration and movement absorption capability than Tozenflex.





It is a twin sphere rubber connector made of EPDM. Available sizes are 150mm to 300mm. Working pressure is 20 bar for all sizes. Tie-rod integrated type floating FCD flange is the standard flange, and a set of tie rods are supplied as standard package. Ordinary FCD floating flange is also available. JIS10K and ANSI 150 are our standard flange drillings. Other material and drilling standard of flanges can be supplied upon request. In general, Twiflex 20 has higher pressure resistance and shorter face to face length than Twinflex


Tozenflex is single sphere type rubber connectors, and made of EPDM. Available sizes are from 40mm to 300mm. Maximum working pressure is 16 bar for all sizes. FCD ANSI 150 and JIS 10K floating flanges are standard onnectors to Tozenflex. Other materials and drilling standards of floating flanges can be supplied upon request. Tozenflex is commonly suggested for piping systems in general building and industrial services.


PT-LS is a spool type rubber flexible connectors (or rubber expansion join). Since

PT-LS is made by hand-made process, customization is available to fulfill specific/special requirements of sizes (up to 2000mm available), lengths, working pressure (max: 40 bars for small sizes), movements, and connections. Flanged ends, beveled ends, insertion end are available for different pipe connection. PT-LS can be produced for above-ground and underground applications. Standard material is neoprene and EPDM is optional. PT-LS is widely used in general piping systems requiring higher pressure resistance and movement absorption capability where other models are not suitable. PT-LS is popularly used in large-sized piping systems of public waterworks and wastewater projects to solve differential settlement problems (land sinking). images3


Flexidrain is a spool type rubber flexible connector for underground drainpipes. Both flanged type and insertion are available. Flexidrain is made of natural rubber and available from 25 mm to 250 mm. The maximum working pressure is 1 bar.