Identify the type of waterproof casing pipe
1. Rigid or flexible
Choose according to the specific usage scenario. If it is in an environment where the pipe will basically not move, such as the static water supply and drainage pipe on the outer wall of the basement of a general building, the rigid waterproof casing pipe can meet the requirements; if the pipe may move or vibrate, such as passing through the wall of a pool or in an area where settlement is possible, you need to choose a flexible waterproof casing pipe.
2. Other special types
For example, in a chemical environment with special anti-corrosion requirements, you may need to buy waterproof casing pipe with anti-corrosion coating or special materials (such as stainless steel); in occasions with fire protection requirements, consider fireproof waterproof casing pipe.

Check product standards and specifications
1. Compliance with standards
Make sure that the waterproof casing pipe meets the relevant national standards or industry standards. For example, waterproof casing pipe for construction should meet the 02S404 standard, etc. Check the product's quality inspection report, certificate of conformity and other documents to verify whether it has been formally tested.
2. Specification Matching
Carefully check the specifications of the waterproof casing pipe, including nominal diameter (DN), outer diameter, inner diameter, wall thickness and other dimensions. These dimensions should closely match the actual installed pipe size. For example, if the water supply and drainage pipe has a diameter of DN100, it is necessary to select a waterproof casing pipe of the corresponding specification, and pay attention to whether the wall thickness of the casing pipe meets the requirements of waterproofing and pressure resistance.

Material Quality
1. Material Composition
For metal waterproof casing pipes, it is necessary to understand their material composition. For example, for casing pipes made of carbon steel, it is necessary to pay attention to the carbon content and whether it contains other alloy elements, which will affect the strength and corrosion resistance of the casing pipe. For casing pipes made of stainless steel, it is necessary to clarify which specific model is 304, 316, etc. Different models of stainless steel have great differences in corrosion resistance and price.
2. Material Quality Verification
The material quality can be confirmed by checking the material test sheet of the product or asking the supplier to provide material guarantee. For materials with special performance requirements, such as corrosion resistance and high temperature resistance, it is best to have relevant performance test reports.

Factors related to sealing performance
1. Quality of sealing materials
For flexible waterproof casing pipe, the quality of rubber sealing ring is crucial. Check the material, hardness, elasticity and other parameters of rubber. High-quality rubber sealing rings should have good water resistance, aging resistance and elastic recovery ability. For example, sealing rings made of EPDM (ethylene propylene diene monomer rubber) have good aging resistance and water resistance.
2. Sealing structure integrity
Check whether the sealing structure of the waterproof casing pipe is reasonable. For example, whether the water stop wing ring of the rigid waterproof casing pipe is welded firmly and the size meets the standard, whether the pressure plate of the flexible waterproof casing pipe is tightly matched with the casing pipe body, and whether the fastening parts such as bolts can effectively apply pressure to make the sealing material work.

Product appearance and processing quality
1. Appearance inspection
Check whether the surface of the waterproof casing pipe has defects such as cracks, sand holes, rust, etc. For metal casing pipes, the surface should be smooth and flat without obvious unevenness; for plastic casing pipes, there should be no bubbles, impurities and other problems that affect the appearance and performance.
2. Processing accuracy
Check the processing accuracy of the casing pipe, such as the flatness and roundness of the pipe mouth, the dimensional accuracy and position accuracy of the water stop wing ring and other components. High-precision processing can ensure that the casing pipe is better installed and performs its waterproof function.

Supplier reputation and after-sales service
1. Supplier reputation
Choose a supplier with good reputation. You can find out by checking the supplier's customer reviews, industry reputation, etc. Reputable suppliers are more guaranteed in terms of product quality and delivery time.
2. After-sales service
Ask the supplier about the after-sales service content of the product, such as whether the product provides return and exchange services if there are quality problems, whether there is technical support to guide the installation, etc. Good after-sales service can reduce the user's losses when encountering problems.