Liner application for waste chute repair


Impregnated needle felt hose liners have long been regarded as a standard means of rehab­ilitating sewers and pipes. However, they are usually used in the horizontal. The vertical application of such liners is a rare event in practice, but nevertheless feasible – as convincingly demonstrated by the rehabilitation of a waste chute in an apartment block in Gibraltar with Konudur HL needle felt hose from MC.
A waste chute has to deal with tremendous loads of rubbish – in the truest sense. In an apartment block in Gibraltar, the concrete of the building’s waste chute had significantly degraded over the years and therefore needed to be repaired in order to return it to functional integrity.  The sewer and pipe renovation company, Enviroflow, based in Gibraltar was duly awarded the job. This specialist firm has been working with MC products for many years and is very familiar with their capabilities. They therefore recommended that the 30 metre long chute be repaired using a needle felt liner impregnated with Konudur 160 PL-XL, a resin system from MC. This, they felt, would ensure a fast, cost-efficient and durable repair.

The access to the waste chute on the roof of the apartment block (left). Once it had been impregnated, the liner was inverted for installation.
The access to the waste chute on the roof of the apartment block (left). Once it had been impregnated, the liner was inverted for installation.
© MC-Bauchemie 2014

A tricky task for both material and contractor

The vertical arrangement of the chute and the high temperatures involved were the biggest hurdles. The liner also had to be inserted from the top, that is to say from the flat roof, into the chute. Moreover, the needle felt hose had to be impregnated on the roof immediately prior to installation. Enviroflow opted for the solvent-free epoxy resin Konudur 160 PL-XL as this offered very good adhesion to the concrete substrate, would not shrink and would achieve a high-strength finish; importantly, it also would not create unpleasant resin smells in the building. Konudur 160 PL-XL cures under ambient conditions, i.e. without any heat input, and exhibits shorter pot times than other systems. In order to avoid Gibraltar’s high temperatures, wetting out of the liner began at sunrise while work could still be carried out in the relative cool. Immediately before inversion into the chute, the needle felt was impregnated with the epoxy resin and then rolled to ensure that the resin was evenly distributed. The installation technique involved using a slug of water of no more than 50-100 litres to invert the liner. This small volume was sufficient in order to carry the end of the hose to the bottom of the chute without overloading or overstretching it. Once the water had been released, the liner was inflated with a little compressed air so that it was firmly pressed against the chute walls. The system was then allowed to cure with the compressed air still being applied. The following day, the top and tail were trimmed, and the access points at each floor level were reinstated and finished off. The waste chute was then put back into service.
Major experience with liners

Short liners or patch liners from MC are generally recognised in the UK as products rehabilitators can rely on. MC offers extensive experience there in the use of long and short Konudur liners with diameters ranging from 100 to 1000 mm. “Each month around 500-800 sewers and ducts are repaired with it,” says MC employee Kenneth MacLeod, “and wherever you are in the UK, you will probably be no more than a few kilometres away from an MC liner installation.”

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