SRX Instructions (New Version)

METU-FORM SRX Joining Clips Instructions (new SRX version)

METU-FORM Unloading Operations and Checks

The installation of an oil-tight ventilation system requires much care. Oil penetrates into the smallest cracks and pores of any material. Even by minimal leakages a drop is formed as oil, unlike water, does not evaporate easily. Because of the oil‘s relatively thick consistency, several months could pass by till the first drop falls.

The manufacturer is responsible for delivering the ordered components.

In order to guarantee the oil-tightness, the installer‘s responsibility is to make sure that:
-    the duct elements are not damaged,
-    the assembly (and especially the connections) is done properly.

It is therefore important to read the relevant instructions before starting assembling the ducts.
Should you have any quetions please do not hesitate to contact us.

Unloading Operations

Always unload in presence of the lorry driver.

During unloading, the parts and the quantities should be compared with the delivery slip.

Make sure that all relevant documents are duly signed (name also in plain writing) by the person in charge.

Any discrepancies or damaged parts should be noted in the delivery slip and the relevant paperwork. Any claims must be sent to us in writing within three (3) days.

We should also be notified immediately per phone as well in order to react promptly and avoid unnecessary delays.

Please make sure that the goods are discharged carefully from the lorry, as the unloading operations are legally part of the assembly.

Handling and stocking on Site

Do not drag the upright ducts or fittings on the floor, as this might damage the flanges and the zinc coating. Always use adequate transport equipment which minimizes the risk of damages. As a rule never stock the goods outside, as white rust might occur.

Ducts should be stored in an upright position in order to avoid indents or deformations due to their own weight. Do not place ducts and fittings directly on the floor, but always on an adequate support such as wood.

Visual Control
In order to avoid indents or scratches which could lead to leakages, it is important to check the ducts and fittings (particularly the formed-on flanges) twice before assembling them:
-    when the goods are unloaded (liability transfer), and
-    just before the assembly of every single component.

Appearance of the Flanges

Looking for distortions, damages, specks of dirt on the formed-on flanges which could lead to leakages:

  1. Parallel Flange
  2. Any deformations of the tension surfaces of the flange would negatively affect the centering of the flanges
  3. Any distortions, jags, accumulation of dirt on the indicated surfaces would hinder the effectiveness of the gasket.
  4. Any deformations or dirt accumulation could affect the centering of the flanges.

Looking for distortions, damages, and uneven flange surfaces:

Any deviations would increase the squeezing effect of the SRX joining clips, thus jamming the flanges which would no longer be able to align themselves freely:


Checking the roundness by determining if there are any deviations from the standard Ø through deformations: 

A:  Minimal-Ø
B:  Maximal-Ø
C:  Nominal-Inside-Ø


The SRX Joining Clips are only able to cover small Ø deviations and still center the flanges properly. The SRX Joining Clips can be used as long as these Ø deviations do not exceed 2% of the nominal diameter. 

Max. allowed deviation for a 1000 mm Duct-Ø = ± 20 mm
Max. allowed deviation for a 200 mm Duct-Ø = ± 4 mm

What to do when Damages are detected?

Small indents and slight duct damages have generally no consequences as long as they are not near or on the parallel flanges. Assuming that the ducts must not fulfill any aesthetic requirements, as it is the case for apparent ducts (stainless steel is easily scratched), there is no reason to replace them. With a little skill such minor damages can be fixed on site. Exceptions are ducts which must be subjected to higher negative pressures and when the damages are near the welds.

Should you detect any damages, deformations and irregularities on the parallel flanges, these are on most cases beyond repair! One must take into consideration that a leakage at a later stage would prove much more expensive than the immediate replacement of the damaged parts. This is why damaged ducts should never be used!

Should the decision be taken to still use these damaged ducts, an adequate and oil-resistant sealant should be applied between the parallel flanges as an additional security. After that the flanges can be connected normally using the SRX Joining Clips. The above measure should be used anytime there are concerns about the accuracy and the air-tightness of the duct connections.

Repairing deformations or damages of the parallel flanges on site are out of the question. The only exception is when the duct or fitting are slightly oval (max. +/- 10%). In this case these could eventually be corrected on site, making sure that the deviation from the standard diameter is within the allowed limits (please refer to the „Visual Control“ section above).

Deformed or damaged SRX Joining Clips should not be used. Should the gasket have fallen, it is possible to put it back in place. To achieve this it is recommended to take an original SRX Joining Clip with the gasket properly mounted as a reference. A gasket not correctly positioned might lead to leakages. Gaskets should never be glued into the SRX Joining Clips, as they need to be able to slide during the tightening operations.


SRX 12 (Ø 80 to 180 mm) : SW = 4 mm
SRX 13 (Ø 200 to 450 mm) : SW = 6 mm
SRX 19 (Ø 500 to 1000 mm) : SW = 8 mm

Ajust to low torque


Open Joining Clip

The SRX Joining Clip is normally delivered in the fully open position (A). Should not that be the case, please open it as depicted below:

There are different SRX Joining Clip designs; the tightening principle remains practically the same:


Gasket Check

The gasket should be positioned inside the SRX Joining Clip groove, and should not sag at any point around the entire circumference:

Cleaning the flanges

Clean and check the formed-on flanges. In case of damaged flanges the part duct or fitting must be replaced!


Hang the SRX Joining Clip on the formed-on „Parallel“ flange

The duct weld and the Joining Clip must be aligned, and both must be placed on top of the duct or sideways:

The area of the joining clip with the tightening device must rest on the formed-on flange. Pressure in that area should be applied during the tightening process in order to prevent the gasket from slipping away. The above must also be practiced if the ducts are installed vertically:

Insert the second duct section into the lower part of the joining clip and let it rest at the bottom of the joining clip. The weld must be located on top:

Tighten the SRX joining clip until both ends meet. The ducts are automatically aligned when the joining clip is tightened. For the installation an impact wrench can be used:

Closed joining clip:
Should you experience difficulties tightening the SRX Joining Clip, this is an indication that the flanges did not align themselves correctly. The cause should be clarified before continuing the installation:



  1. SRX Joining Clip
  2. Parallel-Flanges
  3. Duct wall
  4. This height must be checked along the entire circumference.

A constant distance (4) between the top of the SRX Joining Clip and the surface of the duct, as indicated below, indicates a correct centering. This distance must be checked along the entire circumference of the SRX Joining Clip and on both sides:

SRX Ø 80 to 180 mm :  ≈ 6,0 mm
SRX Ø 200 to 450 mm :  ≈ 12,5 mm
SRX Ø 500 to 1000 mm :  ≈ 18,0 mm

The gasket is not glued inside the SRX Joining Clip, as it must be able to slide along during the tightening process. The illustration below shows a faulty installation.

When dismantling the SRX joining clips,
we recommend to always replace the gasket.

Should the Parts be Pre-assembled on the Ground?

It is up to the installer to decide how many parts should be pre-assembled on the floor before being suspended at their definitive location. The decision largely depends on the duct diameters and the available lifting equipment. It is to be noted that too long pre-assembled sections might put excessive stress on the connections when lifted. These might deform, thus leading to potential leakages. 

Another concern is that the increased weight can lead to deformations when the pre-assembled duct section is placed on the lifting equipment. Should these deformations occur in the vicinity of the duct ends and/or a parallel flange, leakages might also occur.

Quality is everyone's concern

Discharging operations carried out with care.


Assembly of METU-FORM oil-tight ducts

NBR Gasket



SRX Equipotential Bonding