On integrity and maintenance of sewers

Summary

The issues of the integrity and maintenance of gravity sections of sewers are discussed. The pipelines (water, heat and gas) of the municipal utility infrastructure are characterized by pressure flow of the work product. Depressurization in such pipelines causes failures. Determining the initial stage of a gravity sewer failure is very difficult; therefore minor pipe leakages under small pressure can continue for prolonged periods. This fact requires sewer regular maintenance to ensure its integrity. However, the regulatory documents in many cases do not take into account the operation experience. Main sewer failures are blockages and structural damages. To reduce the number of blockages it is suggested to increase the minimum diameter of outdoor sewer pipes to 200 mm. To improve the conditions for sewer repair draining of pipes is recommended. A layout of installing a permanent bypass for sewer section draining for inspection, maintenance and repairs is suggested. Relatively small length of the drained sections (150–200 m) will provide for laying bypass pipe with significant fall eliminating excess digging in so that high liquid velocities and flows are ensured, and reduced bypass diameter and energy saving are predetermined. Permanent bypasses provide for high quality maintenance that in the long run extends the service life of the facilities.

Key words

reliability , maintenance , gravity sewer , draining , bypass installing , inspection , repair work

The experience of establishing vibration diagnostics laboratory

Summary

The equipment life time includes the stage of maintenance and repair. Maintenance and repair control aims at reducing equipment outage and maintenance expenditures. Very often this stage is vitally important for industrial enterprises since maintenance expenditures are rather high. For the Russian enterprises maintenance and repair expenditures can reach 80% of the profit (the average value in USA and Western Europe is 25–30%). Nevertheless, even with these expenditures the failure rate in industry is too high. All the maintenance and repair expenditures are included into the water and sewerage tariff. Considering the social significance of tariff rates more transparent and reasonable repair process must be worked out. The control philosophy improvement, tools of technical control and diagnostics of the equipment condition provided for enhancing the efficiency of equipment maintenance and repair control. However, the operating experience shows that they did not gain widespread currency at the Russian industrial enterprises. In Tumen Vodokanal a vibration diagnostics laboratory has been established that carries out pumping unit vibration control and alignment at the company facilities. The conducted works ensured reducing pumping unit failures and improving the efficiency of cash flow distribution for the equipment repair.

Key words

rehabilitation , pumping unit , maintenance , vibration diagnostics , alignment , non-destructive control