용접플랜지를 올바르게 사용하는 방법

Welding flanges are widely used in piping systems across industries such as oil and gas, 석유화학, 발전, 수처리, 조선업. They provide a reliable connection between pipes, 밸브, 및 장비, ensuring mechanical strength and leak-free performance. 하지만, to achieve these benefits, welding flanges must be used correctly. Improper handling, 용접, or installation can lead to joint failure, 누출, or reduced service life.

This article explains how to use welding flanges correctly, covering preparation, welding techniques, 점검, and maintenance to ensure long-term reliability and compliance with industry standards.

What Is a Welding Flange

A welding flange is a type of pipe flange designed to be permanently attached to the pipe by welding. The two most common types are:

용접 목 플랜지 (WN) – Features a long tapered hub for butt welding to the pipe, offering superior strength and stress distribution.
슬립온 플랜지 (그래서) – Fits over the pipe end and is fillet welded both inside and outside, easier to install but suitable for lower-pressure service.

~에 SASAFLANGE, welding flanges are manufactured to meet ASME, EN, DIN, and other international standards, ensuring compatibility and performance in various industrial applications.

Step-by-Step Guide to Using Welding Flanges Correctly

1. Select the Right Welding Flange

재료 호환성 – Match flange material to the pipe material to avoid galvanic corrosion and ensure weld quality.
압력 등급 – Choose according to system pressure (예를 들어, 수업 150, 수업 300, 수업 600).
플랜지 유형 – Weld neck for high-pressure/high-temperature systems, slip-on for low-to-medium pressure systems.
Standard Compliance – Follow ASME B16.5, ASME B16.47, EN 1092-1, or other applicable standards.

2. Prepare the Pipe and Flange

Check Dimensions – Ensure bore size, outer diameter, and bolt holes match the mating flange.
표면 청소 – Remove rust, 기름, 유지, and dirt from both the pipe and flange.
Bevel the Pipe End – For weld neck flanges, bevel the pipe to the correct angle for butt welding.
Inspect for Defects – Ensure there are no cracks, 찌그러짐, or other defects on the flange sealing face.

3. Align the Flange and Pipe

Proper Alignment – Misalignment can cause stress concentration, 누출, and premature failure.
Use Alignment Tools – Spacers, jigs, or pipe alignment clamps help maintain accuracy.
Match Bolt Holes – Ensure the bolt holes are in the correct orientation before welding.

4. Welding Procedure

Qualified Welders – Only certified welders should perform welding according to WPS (용접 절차 사양).
Preheating – Some materials, such as alloy steels, require preheating to prevent cracking.
Weld Type:
- Butt Weld for weld neck flanges – Provides a smooth internal bore for fluid flow.
- Fillet Weld for slip-on flanges – Requires welding on both the inside and outside.
Multiple Pass Welding – For thicker flanges, apply multiple passes to ensure complete penetration.
Avoid Overheating – Excess heat can distort the flange or damage sealing surfaces.

5. Post-Weld Inspection

육안검사 – Check for cracks, undercut, porosity, or incomplete fusion.
비파괴 테스트 (NDT) – Use ultrasonic testing (유타), magnetic particle testing (MT), or liquid penetrant testing (PT) as required by the project specification.
Dimensional Check – Verify that the flange remains within tolerance after welding.

6. Gasket Installation and Bolt Tightening

개스킷 선택 – Choose the correct gasket type (spiral wound, 링형 조인트, soft gasket) for the service condition.
Bolt Lubrication – Apply approved lubricant to threads and nut faces for accurate torque.
Tightening Pattern – Use a cross or star pattern in multiple passes to ensure even compression.
토크 제어 – Follow specified torque values for the bolt size, 재료, 개스킷 종류.

7. 압력 테스트

수압 테스트 – Checks for leaks at a pressure higher than operating pressure.
Pneumatic Testing – Used for low-pressure systems or where water is unsuitable.
Safety Precautions – Always follow safety standards when performing pressure tests.

8. 유지보수 및 검사

Regular Checks – Inspect bolts, 틈 메우는 물건, and sealing surfaces periodically.
Corrosion Prevention – Apply protective coatings or anti-corrosion tape if exposed to harsh environments.
Re-Torque Bolts – For systems subject to vibration or thermal cycling, bolts may need re-tightening during initial operation.

Common Mistakes to Avoid When Using Welding Flanges

Incorrect Material Selection – Leads to corrosion or thermal expansion mismatch.
Poor Alignment – Causes leakage and uneven gasket compression.
Over-Tightening Bolts – Damages gaskets and sealing surfaces.
Skipping NDT – Increases the risk of undetected weld defects.
Inadequate Cleaning – Oil, 녹, or debris can compromise weld quality and sealing.

Advantages of Correct Welding Flange Usage

Leak-Free Connections – Proper welding and bolt tightening ensure tight seals.
Extended Service Life – Minimizes wear and corrosion.
고강도 – Welding creates a permanent, strong bond between pipe and flange.
다재 – Suitable for various pressure classes, 온도, and environments.

결론

Using welding flanges correctly involves more than just attaching them to a pipe. From selecting the right flange type and material to proper welding, 점검, 및 유지 보수, every step must follow strict industry standards and best practices. When installed and maintained correctly, welding flanges deliver excellent sealing performance, 구조적 완전성, and long service life in industrial piping systems.

With expertise in manufacturing high-quality welding flanges and providing technical guidance, SASAFLANGE ensures that customers get reliable, 준수, and durable flange connections for even the most demanding applications.