Flange Fixing Technology

Mating flange

The fixing of the penetration seal needs to be performed in keeping with specific rules in order to assure reliable sealing of the flange connection. Ideally full face rubber flanges shall be clamped to flat face pipe flanges.

It is essentially required that any recess or raised face of pipe flanges must be equalized in order to avoid damaging of the rubber flange surface. If the recess or raised face is specified in advance ditec can offer to integrate the negative of the recess or raised face into the rubber flange. Then no extra measurements such as separate steel plates or additional rubber gaskets to flatten the surface need to be taken onsite.

Penetration seals for large GRP pipelines require a laminated flange on the outside with enclosed bolts to seal the inner rubber flange of the penetration seal securely. In the best case, the wall pipe is given a flange that projects beyond the wall, which facilitates the installation of the wall duct expansion joint. In order to simplify the formwork for concreting the wall, the wall pipe flange should often be flush with the wall. This requires special design measures on the flange, such as welded-in cap nuts.

Alternatively penetration seals can be clamped to the cylindrical end of the wall pipe and onto the outer diameter of the pipeline using clamping clips. These joints are designed to slip over the straight ends of the open pipe and be held securely in place with clamps. This type of joint is recommended only for low pressure and vacuum service because of the difficulty of obtaining adequate clamp sealing. At higher pressures (1 bar) and greater nominal diameters (> NB 500), the fixing of a sleeve expansion joint may lead to sealing problems. There is also the risk that the expansion joint will be pulled off the wall pipe end. For this reason, we recommend that you attach a welding bead or a wire to the end. Depending on pressure and the nominal diameter, endless clamp belt, screw thread belt, small clamps or hinge bolt clamps are to be applied. At higher pressures, 2 adjacent clamps per fastening side are recommended. 

We can manufacture all our slip-on sleeve rubber expansion joint types exactly customized to the requested outer diameter of the wall pipe and piping. Slip-on sleeve rubber expansion joints are self-sealing. So an additional separate gasket is not required.

Flange Fixing Illustrations

Backing flange construction

The backing flanges are designed as flat press-on flanges with or without support collars. The manufacturing process is economical for very large diameters also. For transport reasons, the backing flanges can also be delivered in a split construction. Hereto special measurements such as cutting through the holes or end plates to connect the backing flange parts to form an integral flange on-site need to be taken.