Horizontal-Pipe- Relining

Pipe relining of a 120/160cm ovoid cross-section sewer.

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One day, Philippe Henaut, called us for help.

We drove to the client’s place and found ourselves solving a crisis with 1” and 1¹/₂” hoses.

The mortar pump was finding it impossible to flush out a 20m long 1” hose with water. 2 men were clouting the hoses with club hammers in order to soften the mortar. It all came back to me: I’d so often had that sort of experience before.  Two other men were trying to do the same thing to another hose connected to the Kärcher high pressure pump. The HP safety valve blew at 20 bar. Philippe turned up the pressure, but there was a leak in the pressure gauge. The HP pump built up pressure to about 30 bar then broke down. Neither of the hoses could be saved.

We realised our help was needed. We told the crew we’d fetch some 35mm hoses and a few small parts, e.g. a female/female connector for the mortar hose male attachment. The rinsing hose has a male connector and so the mortar hose can only be connected in one direction. Using this coupling the hose can be turned round, which is often a way to save the mortar hose in an emergency. Otherwise flushing the centrifuge motor pipe would badly damage it and it would have to be changed.

No sooner said than done.  We were back on site in about an hour with tools and all the necessary parts. We were eagerly awaited: the crew were inexperienced and the site manager had never had to coat a 1m60 high ovoid cross-section sewer before.

We changed the centrifuge pipe, installed the centrifuge spray-head, and the crew got everything into the sewer. The hoses were connected to the pump and they were all eager to go. They thought everything was OK! BUT… Never trust those who ask you for help. First we instructed them to check the rotor/stator pressure. Philippe attached his test valve and we started to pump water through. To the crew’s surprise, we couldn’t build up any pressure.  We tightened connections as far as they would go and reached perhaps 5 bar. Philippe pointed out that hardly any water was being pumped from the pump.

We changed the stator. One of the operators showed me the rotor – I was speechless. I had never seen such a worn rotor – or rather, only once many years previously.  There were deep grooves in the steel, probably because of hours of grinding with water and sand.  Anyway, we changed the complete rotor/stator assembly and adjusted the water pressure at 35 bar. Then we mixed up cement slurry and pumped about 10 litres of slurry into the hoses. Next we started up the M-Coating continuous flow mixer and began on the coating. Along a 45 metre hose, with the M-Coating pump on position 2, that gave about 28 bar. The mixer delivered about 13 litres per min and we were pumping 6 to 7 litres per min. After a short time the word came back from the sewer that everything was looking good. In this way, we slowly sprayed mortar onto the 120/160cm ovoid cross-section sewer. Everything was working fine. The ERGELIT-KS1 was being mixed in a continuous, even flow.

Once the first 20 m of hose came back out of the sewer, we stopped the pump, disconnected the hose and continued coating. We flushed the mortar hose with a sponge ball and water from the HP pump. Meanwhile the crew had established that not enough water was getting to the HP pump and the pump’s low water pressure switch was then shutting the pump off. The work continued with the remaining hose, at a rate of about 9-10 litres and about 18-20 bar. The coating array proceeded centimetre by centimetre. About an hour-and-a-half and many little tips and explanations later, we took our leave. The coating was still going on. The site manager and his team were relieved. They’d be able to complete the coating of another 40 metres of sewer that day. The manager came over to the car and thanked us again and again for our help.

 

As the rescue team, the two of us were glad to have been able to carry out a successful assignment. It doesn’t always go so smoothly and we can’t always say “ We came, we saw, we conquered.” But this time we’d spotted all the problems and solved them.  That sort of work is fun. This is what we’re all about!  It shows the client how good we are – and that we’re a hard act to follow.

It’s a pleasure to work with ERGELIT-KS1, the premier specialised sewer rehabilitation mortar.  

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