As a manufacturer specializing in the production of drainage pipes, in addition to hdpe pipes for drainage, we can also provide Krah pipes. Compared with double-wall corrugated pipes, this product is slightly less used, but its performance is better. Next, I will introduce Krah pipes to customers. The relevant knowledge, including the technical characteristics of Krah pipe, the quality control of Krah pipe, the construction and acceptance of Krah pipe.

Technical characteristics of Krah pipe

Krah pipe is a special structural wall pipe with high resistance to external pressure made of high-density polyethylene resin as the main raw material, using hot winding molding technology, and polypropylene (PP) single-wall corrugated pipe as the auxiliary support structure.

The Krah pipe has superior technical characteristics:

1. Krah pipe adopts a hot winding molding production process with high melt quality. The 190°C flat material tape and U-shaped material tape extruded from the die of the extruder are evenly wound on the heated roller mold according to the predetermined position. The quality of the weld seam of the structural wall pipe is guaranteed. Especially in the structural design, the welding seam of the flat strip is covered by the cladding support tube, which improves the overall external pressure resistance of the tube.

2. Krah pipe installation performance is excellent. The pipe connection adopts the socket electric fusion connection technology of pre-embedded electric fuse in the same material, the connection quality is high, and the interface has zero leakage, which ensures the safety of the entire pipeline system operation. Moreover, the Krah pipe is light in weight and easy to transport; the amount of excavation of the trench is small, no concrete cushion and concrete pipe foundation are required, and the pipe can be laid directly after the groove is qualified, and it can be excavated, piped down and backfilled at the same time , greatly shortening the construction period, especially to alleviate the traffic congestion caused by urban municipal engineering construction, and the social and economic benefits are obvious.

3. The inner wall of Krah pipe has low roughness and large water delivery capacity. The roughness n of the inner wall of Krah pipe products is 0.009, and the specific frictional resistance is small when transporting fluids. Therefore, Krah pipes with smaller inner diameters can be used to replace cement pipes with larger inner diameters; and the flow rate is fast, and it is not easy to deposit silt, which saves maintenance costs.

4. Krah pipe has good flexibility. Based on the principle of pipe-soil interaction, it has a strong ability to withstand external loads. The pipe has good flexibility. When geological activities such as earthquakes and uneven ground settlement occur, the damage loss of the pipe can be minimized. Thereby improving the ability of public facilities to resist earthquakes and reduce disasters. In addition, Krah pipe also has the properties of anti-corrosion, anti-aging and long service life, especially suitable for chemical drainage and wharf drainage pipeline projects where the groundwater is seawater.

Quality control of Krah pipe

The production of Krah pipe has established a relatively complete quality and environmental management system according to the international standards of Is09001 and Is014001, so as to control the quality of the whole process of product manufacturing and use, specifically:

(1) For product design and selection control, refer to the above content.

(2) Raw material control: The main raw material is 6100M from Beijing Yanshan Petrochemical, and the incoming inspection is carried out according to the standard requirements.

(3) Processing technology control: In the process of product processing, the overlapping quality of the welded seam and the coating quality of the PP pipe are especially controlled to ensure the quality of the welded seam and prevent side exposure.

(4) Carry out factory inspection and type inspection according to national standards.

Construction and acceptance of Krah pipe

After years of application, Krah pipes have accumulated rich experience in installation and construction. The construction technology and acceptance of Krah pipes will be introduced below.

Introduction to the construction process of Krah pipe

1. Tube down: After the acceptance of the pipe groove, pipes with a diameter less than DN1200 can be manually down piped, and pipes with a diameter over DN12cHD are recommended to be hoisted and down piped by mechanical means. When lowering the pipe, the two lifting points of the Krah pipe should be balanced, and the Krah pipe should be placed in the groove smoothly, with the direction that the socket is above the water flow.

2. Pipeline docking and straightening: Before docking, adjust the tap position of the electric fuse of the pipe to the top, and the docking personnel should carefully check whether the electric fuse is intact, and use a dust-free cloth ( Colorless, lint-free cotton cloth) to ensure that the work surface is dry and clean. Use a chain hoist and two soft ropes to complete the docking, straighten the pipe, and adjust the centerline of the two pipes to coincide with the design centerline to ensure that the entire pipeline is consistent with the design direction.

3. Pipeline welding: Pipeline welding is a key process in the entire electrofusion welding process. This process is monitored by professional operators throughout the process. Use a special electric fusion welding machine and other auxiliary fixtures to complete. For pipes of different diameters, adjust the working time and welding current of the electric fusion welding machine. When the temperature changes greatly in winter and summer, the welding time can be adjusted appropriately ( increase or decrease), to meet the process requirements. When the surface temperature of the pipe interface is lower than 60 degrees, the locking fixture (steel belt and support ring) can be removed for the following work.

4. The quality of the backfill of Krah pipe is a key part of the project, so the construction should be implemented in strict accordance with the requirements of the design documents and relevant specifications.

Pipeline Acceptance

There are two test methods of air-tightness or water-tightness to test the tightness of pipelines. In the northern water-scarce areas, the tightness test of pipelines generally adopts the air-tight test, and in the southern regions, the closed-water test is generally used. The above two methods have their own advantages and disadvantages. We recommend the air-holding test. Therefore, the air-holding test does not require water and does not require 24 hours of soaking time. The cost is low and the progress is fast.

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