HDPE Double-wall Corrugated Pipe (DWCP)

Advantages of Double-Wall Corrugated Pipe

• Lower overall project cost: The pipe material features light self-weight, low transportation and hoisting costs, fast construction speed and greatly shortened construction period, delivering better overall engineering cost performance than cement pipes.

• Excellent sealing performance: socket-and-spigot connection with rubber rings delivers strong joint sealing, effectively preventing sewage leakage and secondary soil pollution.

• Resistance to settlement and deformation: The pipe features high toughness and is not prone to cracking or damage when subjected to uneven foundation settlement and minor geological changes.

• Corrosion-free maintenance: HDPE material resists acid, alkali and sewage corrosion and will not rust. It basically requires no later-stage maintenance when buried underground.

• High drainage efficiency: smooth inner wall with low friction coefficient. Under the same caliber, it delivers better water-passing capacity than concrete pipes and is less prone to sediment accumulation and blockage.

• Wide Application Compatibility: Multiple ring stiffness levels and calibers are available. It supports conventional sewage discharge and perforated infiltration drainage, and is applicable to municipal, real-estate, highway and landscape projects.

• Long service life: When buried underground with standard HDPE raw materials, the designed service life exceeds 50 years.

• Eco-friendly: recyclable, no harmful substances leached, suitable for rain-sewage diversion and rural sewage renovation projects.

Application Scenarios of Double‑Wall Corrugated Pipe

• Municipal Engineering: Urban rain-sewage diversion, municipal sewage discharge, stormwater pipe network, drainage connection for manholes

• Real Estate Communities: Underground sewage and stormwater discharge pipe networks for residential quarters and commercial zones

• Road Traffic: seepage and drainage for highway and railway subgrades, culvert drainage; perforated type for subgrade subsurface drainage

• Garden & sports venues: underground seepage and drainage for parks, football fields and golf courses (perforated DWCP)

• Rural sewage renovation: collection and discharge pipe network for rural domestic sewage

• Industrial Projects: Rainwater and light-duty industrial wastewater discharge for factory premises

• Agricultural farmland: farmland flood drainage, waterlogging reduction and drainage for orchards and woodlands

• Cable Protection: Medium and small-diameter pipes can be used as protective sleeves for power and communication cables

FAQ

Q1:Do HDPE double‑wall corrugated pipes have PN nominal pressure and SDR parameters?

A:No. PN and SDR are parameters for HDPE solid‑wall water supply pipes. Double‑wall corrugated pipes feature a hollow structure. They are non‑pressure gravity drainage pipes that bear no internal water pressure. Their core indicator is ring stiffness SN, which resists loads from overlying soil and vehicle compression.

Q2:How to choose double‑wall corrugated pipes made of PE80 and PE100 raw materials?

A:The PE grade affects the pipe's impact resistance, crack resistance and aging resistance, and does not represent internal pressure‑bearing capacity. PE80 is sufficient for ordinary municipal rainwater and sewage applications; PE100 is preferred for construction sites with soft soil foundations, large settlement or severe cold conditions, as it delivers superior crack‑resistance performance.

Q3:How to select the ring stiffness of SN4, SN8, SN12.5 and SN16?

A:

SN4: Burial depth ≤1.5m, for green belts, sidewalks and shallow‑layer drainage;

SN8: Burial depth 1.5‑3.0m, for residential roads and non‑motor vehicle lanes, most commonly used in municipal engineering;

SN12.5: Burial depth 3‑5m, for municipal main roads and motor vehicle lanes;

SN16: For special working conditions of deep burial, heavy load and high soil cover

The greater the burial depth and the higher the ground load, the higher the required ring‑stiffness grade, and downgraded usage is not permitted.

Q4:Can double‑wall corrugated pipes be joined by hot‑melt butt‑welding or electro‑fusion connection?

A:No. The pipe features a hollow corrugated cavity. The high temperatures from hot‑melt and electro‑fusion welding will damage the corrugated structure, directly resulting in the loss of ring stiffness, and the pipe is highly prone to collapse and deformation after being buried underground. The standard method is socket‑and‑spigot connection with rubber sealing rings. For partial repairs, only heat‑shrinkable tapes may be used for external wrapping and sealing; fusing the pipe body itself is not permitted.

Q5:What are the causes of joint leakage during the pipeline water‑tightness test and how should it be handled?

A:Common causes: damaged, reversely‑installed or distorted rubber rings; unpolished burrs on pipe ends; insufficient socket insertion; displacement caused by rock extrusion during backfilling.

Treatment: Replace with intact original rubber rings, fit them properly into grooves and apply lubricant; trim pipe ends; insert the socket up to the marking line; backfill the joint area with fine sand preferentially; reperform the water‑tightness test.

Q6:What should be done if the laid pipes float upward and shift due to a high groundwater level?

A:HDPE pipes have a density lower than water, and accumulated water in trenches will generate buoyancy. Dewatering shall be carried out before pipe‑laying during construction; dewatering can only be stopped after backfilling is completed; ballast anti‑floating measures shall be adopted for projects with high water levels.

Q7:How to solve the frequent water seepage at the connection between pipes and inspection wells?

A:Due to the inconsistent settlement between plastic pipes and inspection well masonry, direct rigid sealing is highly prone to cracking and water leakage. Where the pipe extends into the well, a flexible transition intermediate layer shall be constructed at the joint position in accordance with specifications, and rigid sealing with mortar shall not be adopted directly.

Q8:Can double‑wall corrugated pipes be stacked outdoors for a long time?

A:It is not recommended. Pipes have poor UV‑resistance, and long‑term exposure to open‑air sunlight will accelerate aging and brittleness. Store them indoors or under cover whenever possible; open‑air storage is recommended for no more than 6 months.

Q9:Can double‑wall corrugated pipes be used for siphon drainage and pressure water conveyance?

A:No. This pipe is only suitable for gravity‑flow rainwater and sewage discharge and has no pressure‑bearing capacity. It will be flattened under negative‑pressure siphon conditions, and it is strictly prohibited to be used as a water supply pipe or siphon pipe.

Q10:What are the mandatory requirements for backfilling?

A:Lay fine sand for the pipe‑base bedding; backfill symmetrically on both sides of the pipeline and compact in layers with a single‑layer thickness of 250‑300 mm; no stones or construction waste are allowed within 500 mm above the pipe top, and direct compaction by heavy‑duty road rollers is prohibited; qualified native soil may be used for backfilling above 500 mm of the pipe top.

Q11:How to distinguish between the inner‑diameter series DN/ID and the outer‑diameter series DN/OD?

A:DN/ID stands for nominal inner diameter, which is widely used in domestic municipal projects; DN/OD stands for nominal outer diameter. The series must be specified when placing purchase orders to avoid connection failures caused by mismatched dimensions.