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| Cement Mortar Lining System For Steel and Cast Iron Piping Time and chemical action can cause problems in your water piping like those in the before and after photos. Dakota Pipelining offers a solution to the problem of corrosion and encrustation in your steel and cast iron piping at a cost significantly lower than the cost of replacement. Your water supply is maintained, your streets are kept open and your customers discover renewed water supply and water quality.
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| Problems |
| Encrustation of pipe inhibits water flow through the system, overworking pumps and increasing energy costs. Low pressure results from the rough or cracked pipe walls, and corrosion internally on cast iron or steel pipe affects water quality and flow. Pitting on pipe surfaces lead to sediment laden water and fouling of the system. Hydraulic losses result in increased pump loads and reduced fire fighting capacity. Chlorination requirements rise steadily as pipes become further contaminated and customer complaints increase as water quality and pressure deteriorate. |
| Results |
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Clean, cement-coated pipe surfaces do not contaminate or impede water flow. Pipes free of
corrosion and encrustation assure increased flow and normal operating pressures. Corrosion
protection, resistant to mechanical and chemical attack, is achieved and fire fighting
capacity is restored to safe levels. Minimal chlorination is required and clean, better
tasting water flow is ensured for years, the result of cement mortar lining treatment,
guarantees customer satisfaction.
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| Cement Mortar Lining…
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| Why The Need? |
| From the early 1900’s to
the late 1950’s, unlined cast iron pipe was the material of choice for
potable water distribution throughout the United States. Since the mid
1950’s, cement-lined cast iron pipe, as well as asbestos cement,
ductile iron and PVC pipe have been introduced as alternatives to cast
iron for smaller sized pipes.
The vast majority of these unlined cast iron watermains have had their carrying capacities greatly reduced by the buildup of tuberculations in combination with mineral deposits known as encrustation. The rate and degree of encrustation varies as the quality of the water varies throughout the country. This buildup reduces the pipes’ carrying capacity while it increases pumping and maintenance costs. Encrustation reduces the capacity of the water system to meet peak water demands and fire protection needs, and it becomes more of a problem to control the growth of bacteria within the system. |
| A Cost Effective Solution |
| A system has been devised to clean and line sound cast iron pipes, returning them to near-original capacity while eliminating future encrustation and tuberculation in the main, generally at 1/3rd to 1/2 the total cost of watermain replacement. The process works this way: |
| Bypass System |
| First, a bypass water system is installed along the curb lines of the area to be cleaned and lined. This bypass system consists of temporary pipe sized to meet the requirements of the area and includes temporary fire hydrants. The residences are connected to the bypass system through their spigots on the outside of the home or at the curb stop during the approximate three-week period that the system is shut down. |
| Access Pits |
| After the bypass system has been completed and sterilized, access pits approximately four feet by eight feet are dug every 300 to 700 feet. A four-foot piece of pipe is cut from the watermain and a cable is inserted in the pipe. |
| The Cleaning Process |
| Scrapers of various sizes are then pulled through the pipe section by winches located at each end of the pipe; these are followed by piston-type rubber squeegees to remove any remaining debris. |
| The Silver Lining |
| The lining unit, which includes a specialized hose combining high pressure cement mortar feed hose, an air pressure hose and a cable, is then pulled through the clean pipe. The lining head, consisting of an air motor and propeller blades, applies the cement mortar to the pipe walls by centrifugal force. The lining thickness is controlled by the pumping rate and the pulling rate of the lining assembly. Stainless steel trowels follow the lining assembly to produce a dense smooth surface. In order to clean water service connections, the service valves are momentarily opened after the concrete has reached its initial set. The cuts in the line are then either repaired or new valves may be installed at the discretion of the local utility. The line is then filled, sanitized and returned to another forty or fifty years of service. |
| The Proven Process |
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Rising material and construction costs have made cement mortar lining very competitive with other lining systems as well as with renewal methods. Generally, Cement mortar linings can save one third to one half over conventional reconstruction or replacement methods. Cement Mortar Lining is cost competitive because of the minimal surface preparation required prior to application, and because of the long life-expectancy of the product. Dakota Pipelining Systems offers two application methods, depending on the size of the pipe. They are the "Drag Trowel Method" and the "Rotary Trowel Method". Drag Trowel Method:
Rotary Trowel Method:
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| Mortar Pumps |
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Dakota Pipelining design and builds a range of pumps specifically for cement mortar lining. These pumps have been developed over many years of field experience. Dakota Pipelining pumps are designed to deliver a continuous calibrated mortar supply to the lining machine heads. Pumping lengths of 1000 feet are achieved. Dakota Pipelining's pumps can operate at high working pressure in the order of 1450 PSI (100 bar), and are designed to handle very stiff mixes. A well-designed pump head with large inlet valves assisted by an auger from the hopper makes it possible to pump two inch (50mm) slumps. |
| Air Liners |
| The air liners, which centrifugally spray the linings onto the pipe walls, are designed to allow side thrust on the rotor bearings resulting in a more reliable machine capable of pulling a drag trowel of up to 24 inches in diameter. The drag trowel method of lining is much simpler than rotary linings, thus giving Dakota Pipelining a decided advantage in the 4 inch (100mm) to 24 inch (600mm) pipe range. |
| Spool Pump |
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This unique machine is designed by Dakota Pipelining for small bore town reticulation systems, and has the ability to line pipes at a rate of over 5000 feet of pipe in a single day. The machine is a single compact unit with a mortar-mixer-pump and reel that will spool up and winch in the mortar hose, air hose and lining cable in one single operation. The mortar hose from the pump is connected to the hose reel via a specially designed high pressure mortar gland. This enables mortar to be pumped into the lining hose while rotating the reel. The hose reel speeds are infinitely variable between maximum forward and maximum reverse via a hydraulic hydrostatic drive. This enables Dakota Pipelining machines to line pipes in the diameter range of four inches (100mm) to 27 inches (685mm) with a lining thickness variation between 1/8th inch (3mm) and 1/2 inch (12mm) over the above diameter range by simply turning the speed control handle of the hydrostatic drive. The incorporation of specially designed mortar pumps enables the placement of linings up to 1000 feet (300m) in length using 1.5 inch diameter mortar hose. Another advantage to this unique spool pump is that there is no preparation of the lining hose as in the orthodox lining method, thus reducing lining time. When a lining is to be placed, the machine is simply parked at the site, leveled by lowering the mechanical and hydraulic control legs, the hose shackled to the pilot line and the prepared lining hose pulled into position by a winch. Mixing can begin with the subsequent pumping and lining operation. There is no need to assemble and disassemble the mortar and air hoses since all these hoses are already on the reel. |
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