Technical Services

Installation Steps

Important Notes

What roles do thrust piers, support piers, and anti-slip components play?

Thrust blocks: Used at fittings such as bends, tees with varying diameters, and blind flanges to prevent pipe displacement. Support piers: Provide structural support for components like fire hydrants, water meters, valves, and check valves, ensuring these pipeline accessories don’t sink under their own weight. Anchor piers: Constructed from reinforced concrete to securely encase and stabilize entire sections of piping, often employed in areas where backfilling isn’t possible—such as inside tunnels. Anti-slip piers: Installed in areas with steep slopes; typically required when the slope exceeds 1:6 to prevent pipes from sliding downward.

How are plastic pipes and fittings bonded together?

1. Before bonding pipes and fittings, wipe the socket side and spigot exterior thoroughly with a dry cloth. If there is oil or grease on the surfaces, use acetone to clean them completely. 2. The pipe cut should be smooth, perpendicular to the pipe axis, and chamfered appropriately. Before bonding, mark the insertion depth clearly and perform a trial fit—however, the trial insertion should only reach 1/3 to 1/2 of the intended depth. If the gap exceeds the recommended limit, never proceed with the bonding method. 3. When applying the adhesive, first coat the inside of the socket, then the outside of the spigot. While coating the socket, apply the adhesive evenly from the center outward along the axial direction, ensuring no areas are missed or over-applied (maximum application rate: 200 g/m²). 4. After applying the adhesive, maintain consistent external pressure for up to 1 minute to ensure proper alignment and straightness of the joint. 5. Once bonding is complete, promptly wipe away any excess adhesive that squeezes out. Avoid applying any additional force or loading the joint during the curing period. 6. Bonded joints must not be installed in rainy or wet conditions, nor should they be used at temperatures below 5°C. 7. Installation procedure: Preparation → Clean the working surface → Trial fitting → Apply adhesive → Bonding → Curing.

Under what circumstances can rubber seals still leak?

During pressure testing or water filling of pipelines, rubber-ring joints occasionally experience leaks. Upon analysis, the main reasons typically fall into the following categories: 1. **Rubber Ring Overturned**: This is the most common issue. During installation, unevenness in the trench bottom, improper alignment of pipe insertion angles, inadequate beveling of pipe edges, or incorrect positioning of the rubber ring can cause the ring to shift forward. Unfortunately, once installation is complete, operators may fail to carefully check with a feeler gauge, leading to the ring being pushed out of the expansion groove. 2. **Substandard Rubber Ring Quality**: Defects such as air bubbles, cracks, or seams in the rubber ring—often resulting from improper vulcanization time—can compromise the ring’s elasticity, rendering it less effective for sealing. 3. **Expansion Groove Too Deep**: If the expansion groove is excessively deep, and equipment malfunctions during the expansion process, the rubber ring might end up not only failing to protrude above the groove surface but instead sinking below it. As a result, the ring cannot properly seal, negating its intended function.

What are the key considerations when bonding or butt-fusing plastic flanges?

In construction, plastic pipes are often connected to cast iron flanges, iron valves, and other pipe fittings using plastic flanges. There are primarily two types of flanges: one is the injection-molded flange for diameters up to φ315 (available in socket and adhesive versions), and the other is the socket-type flange made from various specifications through welding or fiberglass-reinforced composite materials. When connecting these flanges, it’s crucial to first ensure that the standards followed by both the plastic and cast iron flanges match, as well as whether their pressure ratings are identical. Currently, the most commonly applied standard is the national code, though users may occasionally opt for flanges adhering to standards set by the Ministry of Metallurgy or other industry-specific guidelines. Common pressure ratings include 1.0 MPa, 1.25 MPa, and 1.6 MPa. Only when flanges with identical standards and pressure ratings are used can their external dimensions—such as outer diameter and hole spacing—be properly aligned and matched during installation.

What are the precautions to keep in mind when installing sludge discharge valves and air vents?

For long-distance water pipelines, it's essential to install air vents and sludge valves. When installing these valves, keep the following key points in mind: Air vents should be positioned at high points and installed vertically. For underground pipelines, air vents must be placed inside manholes and insulated to prevent freezing. Additionally, on long-distance water lines, an air vent should be strategically located every 500–1000 meters along the route. As for sludge valves, ensure there’s adequate space for removing sediment buildup inside the pipeline and for safely draining contaminants during maintenance or inspection. The sludge valve should be installed at the lowest point of the original pipeline, ideally using a sludge tee that aligns tangentially with the flow of wastewater. Also, account for potential erosion caused by the discharge flow when flushing the system, and make sure to close the valve promptly after installation is complete. Since the branch pipe of the sludge valve can discharge either on the left or right side of the main pipeline, it’s crucial to clearly specify the discharge direction—particularly the orientation of the main pipeline’s socket—in the contract you sign with the customer for customizing the sludge valve.

What are the current national regulations regarding the hygiene and physical properties of rubber sealing rings?

The rubber rings used for potable water supply pipes must be made of food-grade rubber, and their hygiene standards should comply with the "Hygiene Standards for Rubber Products Used in Food Contact," GB4806-94. The rubber rings must be free from air bubbles, cracks, laps, and seams. Their physical properties are as follows: 1. Shore hardness: 45–55 degrees 2. Tensile strength ≥ 16 MPa 3. Elongation at break ≥ 500% 4. Deformation ≤ 20% 5. Aging coefficient > 0.8 (at 70°C, 144 hours)

How do you estimate the amount of adhesive needed when bonding pipes and fittings?

When bonding pipes and fittings, the adhesive is typically applied at a rate of 200 g/㎡. However, account for an estimated 10% wastage. To calculate the required adhesive area, first determine the insertion depth and pipe diameter, then compute the total bonding surface. According to relevant regulations, the insertion depth of the fitting must be at least half the fitting’s diameter plus 6 mm. For example, for a fitting with a diameter of 200 mm, the minimum insertion depth would be ≥ (200 ÷ 2) + 6 mm = 106 mm = 0.106 m.

What are the nominal pressure, working pressure, and design pressure of a pipe?

Nominal pressure refers to the working pressure of water conveyed through the pipe at 20°C. If the water temperature falls between 25°C and 45°C, the working pressure should be adjusted according to a specific temperature correction factor. Working pressure is defined as the continuous operating pressure exerted on the inner wall of the water supply pipeline under normal service conditions—this excludes any fluctuating pressures caused by water flow variations.

Can a significant drop in the drainage pipe of a high-rise building damage the PVC pipe?

Indoors, full-water conditions inside drain pipes are rare, so pressure typically doesn’t build up. However, if a blockage occurs within the pipe, it can lead to full-pipe pressure, potentially damaging the piping material. For high-rise buildings, drainage pipe fittings should be made from materials capable of withstanding pressures of at least 0.3 MPa. At Olive Pipe Industry, our drainage pipes and fittings are manufactured in strict compliance with relevant standards and have successfully passed comprehensive testing, easily meeting or exceeding the 0.3-MPa pressure requirement—making them fully suitable for use. Additionally, in high-rise buildings, elbows are installed at the outlets of floor-level drain pipes. To ensure these elbows have sufficient support and stability, their bases and outer surfaces must be securely anchored with concrete, significantly enhancing their resistance to impact forces.

How do you calculate the expansion length of plastic pipes? What precautions should be taken during construction?

△L = △T × L × α Where: - △L: Expansion/contraction length (mm) - △T: Calculated temperature difference (℃) - L: Pipe length (m) - α: Linear expansion coefficient (mm/m·℃), typically taken as 0.07 For example, in the Xinjiang desert, if the temperature rises to 45°C during the day and drops to 30°C at night, with a pipe length of 6 meters, the calculation would be: △L = (45 - 30) × 6 × 0.07 = 6.3 mm At first glance, a 6.3-mm contraction in a 6-meter-long pipe might seem insignificant for R-R connected systems. However, even a small discrepancy can add up quickly—30 pipes, each shortened by 6.3 mm, would collectively result in a total shrinkage of 189 mm. In practice, these tiny contractions rarely distribute evenly across every joint; instead, they may concentrate into one or a few critical areas, causing sudden gaps at specific connections. This could lead to sections of pipe unexpectedly pulling apart within an already assembled system—a phenomenon that absolutely cannot be overlooked. To address this issue in the Xinjiang desert, where temperature fluctuations are extreme due to time differences, installation is carefully timed for after 4 p.m. in the morning and afternoon. Additionally, timely backfilling is carried out immediately after installation, effectively mitigating the effects of pipe contraction and ensuring a stable, secure pipeline system.

What preparations should be made before conducting a pipeline pressure test?

1. A written hydrostatic test plan must be developed, with clearly defined roles and responsibilities for each team member. 2. All pipeline nodes at both ends and along the route—including support piers for blocking plates and thrust blocks—must be securely anchored and meet the design strength requirements. Valves are strictly prohibited from being used as substitutes for pipe blocking plates. 3. Water should be slowly introduced from lower to higher points until the pipeline is fully filled, ensuring all air is completely expelled. The pressure gauge must be calibrated in advance and must have an accuracy class of at least 1.5. Its measurement range is recommended to be 1.3 to 1.5 times the test pressure, and the gauge’s nominal diameter should not be less than 150 mm. If possible, pressure gauges should be installed at both ends of the pipeline. 4. Backfilling above the pipe top must be completed to a height of at least 0.5 meters, and the pipeline must remain submerged for a minimum of 12 hours before proceeding with further testing or installation.

What method should be used to install plastic pipes when crossing a river?

When plastic pipes cross rivers, it’s essential to first determine the riverbed’s geological structure—specifically, whether there’s an impact from river pebbles—and decide if protective walls are needed. Crossing should ideally be done during winter when water levels are low. Common methods include the cofferdam method, pipe jacking, and the float-and-sink technique. Among these, the cofferdam method is widely used. Here’s how it works: A cofferdam is constructed to block about two-thirds of the river’s width at one end of the crossing point. Water inside the cofferdam is then pumped out completely. Once the area is clear, a trench is dug within the cofferdam, and the pipe is laid. To prevent sewage from entering, the pipe openings are sealed promptly. After backfilling is complete, the adjacent cofferdam section is re-established, and the process of pumping, trenching, connecting, and backfilling is repeated until the entire crossing is finished.

According to the Integrated Wastewater Discharge Standards, is a PVC-U drainage pipe suitable for discharge requirements?

According to the Integrated Wastewater Discharge Standard GB 8978-88 and the Water Quality Standard for Wastewater Discharged into Urban Sewer Systems GJ 18-86, graded standards have been established for wastewater discharge, along with detailed specifications outlining the maximum allowable concentrations of pollutants. PVC-U pipes stand out due to their exceptional corrosion resistance and hygienic properties—they are immune to corrosive effects from pollutants, ensuring that the pipes never scale up during water transport. Additionally, PVC-U pipes feature a low roughness coefficient, allowing for high flow velocities and optimal full-flow capacity. Their lightweight design also makes them easy to install and maintain, effortlessly meeting the minimum slope requirements mandated by drainage pipe standards. For these reasons, PVC-U pipes are perfectly suited to meet national wastewater discharge standards and represent one of the most practical and widely used materials for sewer systems today.

What are the common methods for connecting plastic pipes?

1. Flexible connection (R-R interface); 2. Rigid connection (T-S interface); 3. Flanged connection—commonly used for joining plastic pipes with other types of piping; 4. Plastic welding—employed for chemical pipelines that operate under low or no pressure.

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