Steel cages are manufactured using two fully automatic cage machines. At the beginning the cage diameter, height and pitch are specified on the computer screen and then the cage is manufactured automatically. After the cage is finished the Q.C Supervising Engineer shall check that the diameter of cage and spacing has been manufactured in accordance with the manufacturing drawings.
Most pipes have double cages as reinforcement. In this stage the internal and external cages are being assembled together using stirrups to be moved to the casting yard as one unit.
PCCP type with high pressure must contain a steel cylinder embedded in the concrete core. This cylinder is manufactured, welded and tested before it is introduced to the casting mold.
After the cages are put in the vertical molds, they are closed hydraulically to start casting. Concrete is transferred from the fully computerized batching plant to the mold using electric shuttle. A steel cone fitted on the mold ensures the even distribution of concrete on the entire circumference to ensure homogeneous casting. Concrete is well compacted during pouring using pneumatic vibrators fitted on the internal and external molds.
After initial set of concrete in the mold, low pressure steem is injected within the internal mold to gradually raise the temperature of concrete to accelerate curing. Steam curing is maintained for a minimum of six hours after which the pipe is demolded and put in a curing basin where it is kept in a moist condition for 72 hours prior to turning horizontally and being placed in the open storage area.
High tensile steel wire is wound under tension on the concrete core with steel cylinder embedded inside, allowing concrete pipe to resist high internal pressure.
A layer of concrete coating covers the pipe to protect the steel wires wound on the concrete core.
pipes are being coated according to contract specs internally and externally. Q.C Supervising Engineer shall check the proper application of protective coating and thickness required.
Prior to shipment of any pipe, the Q.C Supervising Engineer shall visually inspect and confirm that the pipe has been manufactured in accordance with standards. If the pipe is acceptable it shall be marked and permitted to leave the factory.