A mixture of cement mortar is typically used as protective interior lining of steel pipe. Applied centrifugally, cement mortar lining provides a smooth dense finish that protects the steel pipe from tuberculation and also affords a measure of corrosion resistance. Additionally, the smooth interior surface of cement mortar lining provides a high flow coefficient, which is generally maintained for a long period of time.

Cement mortar-lined steel water pipe is durable, easily handled in the field, and can be repaired with minimal difficulty.

Raw Materials

Equipment

Batching plant, mortar mixer, buggy with lancing boom, pipe rotators, EOT.

Steam Curing – Steam can be used as a means of accelerating the curing process of the cement mortar lining. For this process, the following items are used:

• Boiler

• Permanent system of steam lines mounted on floor with outlets

• Flexible steam hoses fro insertion into pipe

Wash Down Area – High pressure water-pumping equipment is used in cleaning of batch-preparation equipment, pipe interiors and work areas. The cement mortar lining area is configured with floor troughs and holing ponds so that water used in this process can be recycled.

Specials – For the application of cement mortar lining to pipe miter pieces, angles, bends, reducers and other special sections, hand application is required. Such fittings are generally fabricated from previously lined straight sections of pipe, and thus minimal handwork is required.

For hand lining, the following equipment is used:

• Hand cement mortar mixer

• Welding station for the purpose of attaching reinforcing wire where required

Raw Materials

Copon Hycote 162 HB or paint as per specifications

Cleaning Operation – The first step in internal field coating system, is to re-clean the internal cut-back area after the root pass and hot bead. Attached to the internal line-up clamp is a highspeed brush machine that impinges the weld to remove soot, dust and slag created by the welding process.

The brush machine is centered on the weld and activated for a pre-determined cycle. Upon completion of the cleaning cycle, the brush machine is pulled forward slowly while the vacuum machine travels over the weld to remove all contaminants.

The resulting weld area is now prepared for the completion of the weld, X-ray and coating. Attached to the stern side of the vacuum unit is the cable that travels down the pipe, through other internal machines and connects to a stop trolley or buckle detector.

Coating Application – The internal coating machine is connected to a battery-powered tractor that travels through the pipe without umbilical cables. All operations of the machine are controlled by a programmable microprocessor built with military precision.

The coating machine is centered at the weld area while the weld is induction heated from the outside to approximately 463 degrees F (239 deg C ). Once the weld is to temperature, the technician removes the external control isotope which signal the internal coater to go into a coating cycle. The epoxy powder will be fluidized and blown through the rotating spray head.

The spray head will rotate a pre-determined, but adjustable number of times to deposit the specified width and thickness of coating. The parent coating will be overlapped to ensure an effective and continuous coating. The internal coating machine must be removed from the pipe for servicing and refilling at regular intervals, depending on pipe diameter.

Weld Inspection – A unique video system allows for each coated weld to be visually inspected for acceptance. A two-way communication link is used to connect the external monitor and tape deck with the internal video camera, in real time. The untethered video tractor can transmit several miles into a pipeline and provide clear pictures.