Thin-Walled Stainless Steel Pipe Press-Fit Construction Specifications: Detailed Installation Key Points for DN15-DN100

Thin-Walled Stainless Steel Pipe Press-Fit Construction Specifications: Detailed Installation Key Points for DN15-DN100

In modern building piping systems, thin-walled stainless steel pipes are increasingly favored due to their corrosion resistance, long lifespan, and excellent hygiene. Among them, press-fit technology has become the mainstream connection method due to its advantages such as quick installation, reliable sealing, and the absence of open flames.

In modern building piping systems, thin-walled stainless steel pipes are increasingly favored due to their corrosion resistance, long lifespan, and excellent hygiene. Among them, press-fit technology has become the mainstream connection method due to its advantages such as quick installation, reliable sealing, and the absence of open flames. This article will detail the construction specifications and installation key points for press-fit connections for DN15-DN100 thin-walled stainless steel pipes.

01 Basic Principles and Advantages of Press-Fit Connections

A press-fit connection uses a dedicated pressing tool to simultaneously contract and deform the stainless steel fitting and the pipe material, compressing the sealing ring at the end of the fitting to create a multiple-seal connection.

Additionally, the hexagonal locking structure formed at the press-fit point provides mechanical fixation, ensuring a secure connection. This connection method requires no welding, threading, or hot-melt processing, making it particularly suitable for thin-walled stainless steel pipe systems.

Key Advantages:

Efficient and Fast: The single-point crimping operation is typically completed in seconds.

Safe and Reliable: The crimping point creates a permanent connection that is resistant to vibration and pullout.

Environmentally Friendly and Healthy: No heat is required, which does not affect the pipe's inner wall properties and ensures water quality.

Economical and Reasonable: No special skills are required, reducing labor costs.

02 Pre-Construction Preparation

Material Acceptance and Management

Before construction, all pipes and fittings must comply with design requirements and relevant product standards (such as GB/T 19228.2) and possess factory certificates of conformity and quality certificates.

The appearance of pipes and fittings should be inspected on-site to ensure they are free of cracks, dents, rust, and obvious scratches. Sealing rings should be made of food-grade rubber (such as EPDM or NBR), free of signs of aging or damage, and sized to fit the fitting's sealing groove.

Special Tool Preparation

"If you want to do your job well, you must first sharpen your tools." The following special tools are required for press-fit connections:

Tube cutter: A rotary pipe cutter that produces minimal burrs and cuts.

Deburring tool: A dedicated hair remover or file (must be stainless steel-specific to avoid cross-contamination).

Scriber: Used to mark the insertion depth on the pipe end.

Crimp tool: Select a manual, electric, or hydraulic crimping pliers suitable for the pipe diameter (pressure must be calibrated in advance).

Gauge: A hexagonal gauge used to verify the crimping dimensions.

03 Key Points for DN15-DN100 Pipe Press Installation

1. Pipe Cutting and End Preparation

When cutting pipe, the cut should be perpendicular to the pipe axis, with a deviation of ≤1°. It is recommended to use a rotary pipe cutter that produces minimal burrs and cuts. Avoid using tools that generate high temperatures, such as grinders, to prevent changes in material properties.

After cutting, use specialized tools to thoroughly remove burrs from the pipe end, both inside and outside, and chamfer the end appropriately (usually 15-30°). This step is crucial, as burrs and sharp edges can easily damage the sealing ring during insertion, causing leaks in the connection.

2. Marking and Insertion Depth Control

Use a scriber or marker to mark a line around the pipe end to clearly indicate the required insertion depth. Different pipe diameters have different insertion depth requirements, which must be met.

Insert the pipe straight into the fitting socket until the pipe end meets the fitting's stopper. Verify the distance between the fitting end and the marked line (usually within 2-3mm). This will effectively prevent the pipe from coming loose.

3. Sealing Ring Inspection and Lubrication

Before insertion, ensure that the sealing ring is properly seated in the fitting's U-shaped groove, without any distortion or loss. The sealing ring is crucial for a secure seal and must be free of sand, oil, or damage.

If the insertion is too tight, moisten the pipe and fitting with clean water. Do not use grease or oil-based lubricants. Grease can degrade and ineffectively damage the rubber seal and may contaminate drinking water.

4. Crimping Operation

Mold Selection and Positioning: Align the annular recess of the crimping tool's jaws with the annular protrusion of the rubber ring inside the fitting's end. The tool jaws must be perpendicular to the pipe.

Performing the Crimping: Activate the crimping tool and apply steady pressure until the upper and lower jaws engage or the hydraulic tool automatically releases pressure. The crimping process should be completed in one go; repeated crimping is prohibited.

Pressure Requirements for Different Pipe Diameters: The crimping pressure should be adjusted according to the pipe diameter and should be based on the pressure reference chart provided by the manufacturer.

5. Quality Inspection (Critical Step)

After crimping, immediately inspect the crimping tool with a hexagonal gauge. The gauge should fit fully into the crimping area without any looseness, indicating the correct dimensions and a satisfactory connection. If the gauge does not fit, re-criminate or cut it off and reinstall.

In addition, visually inspect the clamping area. The indentations should be uniform and continuous, free of cracks or indentations.

04 Special Considerations for Different Pipe Diameters (DN15-DN100)

While the basic compression joint process remains the same, there are subtle differences in operation for different pipe diameters:

DN15-DN25 (small pipe diameters): The operation is relatively easy, and manual compression tools can be used. Plastic clamps can be used for securing, but when using metal clamps or hangers, soft spacers such as plastic tape or rubber are required.

DN32-DN50 (medium pipe diameters): Ensure adequate support is provided, and the spacing between fixing brackets should not exceed 15 meters. Tools with higher output power (such as electric or hydraulic pliers) may be required for compression.

DN65-DN100 (larger pipe diameters): Due to the increased weight and rigidity of the pipe, secure the brackets during installation. It may be necessary to apply pressure in stages (first on one side, then on the other), and ensure that the clamping pliers' die size exactly matches the pipe diameter to ensure even pressure distribution. Additional personnel are required during operation to ensure the pipe remains straight during insertion.

05 Hydrostatic Test and Final Acceptance

After the piping system is installed, a hydrostatic test must be conducted to verify the tightness and strength of the entire system.

Test pressure: Generally 1.5 times the piping system's operating pressure, and must not be less than 0.6 MPa.

Test procedure: Slowly inject water to expel all air → Slowly increase pressure (pressurization time ≥ 10 minutes) → Raise to test pressure and stabilize for 10 minutes (pressure drop ≤ 0.02 MPa is acceptable) → Reduce to working pressure and conduct a visual inspection (acceptance is determined by no leakage).

During final acceptance, focus on inspecting the cleanliness, firmness, and tightness of connection points, as well as the installation position and firmness of pipe supports and clamps.

06 Common Problems and Safety Precautions

Lack of tight clamps or missed inspections: Check frequently during construction, using a hexagonal gauge to confirm. No missed clamps or missed inspections are permitted.

If the crimping tool still fails after multiple attempts: Check the crimping tool for integrity and wear. Do not use unqualified tools.

Threaded adapters: Tighten the threads before crimping. Otherwise, the crimping joint may loosen and cause leakage.

Correcting pipe bends: If a pipe bend is detected, correct it at the straight pipe section, not at the fitting, to prevent the crimping joint from loosening.

Safety precautions: Operators should wear a hard hat, protective gloves, and goggles (especially when cutting). Sufficient firefighting equipment should be available on site.

Adhering to correct crimping joint construction practices is the cornerstone of ensuring the safe, reliable, and long-lasting operation of thin-wall stainless steel piping systems. Remember: meticulous preparation, precise operation, and rigorous inspection are the keys to a leak-proof piping system.