Flanges: A Comprehensive Guide for Buyers in 2025


Flanges are essential components in piping systems, used to connect pipes, valves, pumps, and other equipment. Whether you're in construction, oil & gas, or manufacturing, understanding flanges can help you make informed purchasing decisions. This guide will walk you through the types, features, and buying considerations for flanges in 2025.


How to Find Reliable Flanges from China in 2025


China remains a top supplier of flanges due to competitive pricing and advanced manufacturing capabilities. To find reliable suppliers:

  • Check certifications like ISO 9001 and API 6A
  • Review supplier history and customer feedback on platforms like Alibaba
  • Request material test reports for quality assurance
  • Consider manufacturers with in-house testing facilities

What Buyers Should Know Before Buying Flanges from China


When sourcing flanges from China, pay attention to:

  • Material grades (carbon steel, stainless steel, alloy)
  • Pressure ratings (150# to 2500#)
  • Surface treatments (anti-corrosion coatings)
  • Lead times and minimum order quantities

Types of Flanges


Common flange types include:

  • Weld Neck Flanges: Best for high-pressure applications
  • Slip-On Flanges: Easier installation for low-pressure systems
  • Blind Flanges: Used to seal pipe ends
  • Threaded Flanges: For small diameter, low-pressure pipes

Functions and features of Flanges


Key functions include:

  • Connecting piping systems without welding
  • Allowing easy maintenance and inspection access
  • Providing leak-proof connections with proper gaskets

Scenarios of Flanges


Flanges are used in:

  • Oil and gas pipelines
  • Chemical processing plants
  • Water treatment facilities
  • HVAC systems

How to Choose Flanges


Selection factors:

  1. Determine operating pressure and temperature
  2. Select appropriate material for your medium
  3. Choose the right facing type (RF, FF, RTJ)
  4. Consider corrosion resistance needs

Flanges Q & A


Q: What's the difference between ANSI and DIN flanges?
A: ANSI follows US standards while DIN follows German/European standards, with different dimensions and pressure ratings.


Q: How often should flanges be inspected?
A: Annual visual inspections are recommended, with more frequent checks in high-pressure systems.


Q: Can different flange types be connected?
A: Yes, with proper adapters, but matching types is preferred for safety.


Q: What causes flange leaks?
A: Improper bolt tightening, damaged gaskets, or misalignment are common causes.


Q: How to prevent flange corrosion?
A: Use corrosion-resistant materials or apply protective coatings based on environment.