Q1: What types of stainless steel flanges do you offer?

A: We supply a full range of stainless steel flanges, including Weld Neck (WN) for high-pressure systems, Slip-On (SO) for general low-pressure applications, Blind (BL) for sealing pipe ends, Socket Weld (SW) for small diameters, Threaded (TH) for non-welded connections, and Lap Joint (LJ) with stub ends for easy dismantling. Please contact us with your specific needs for recommendations.

Q2: What is the difference between 304 and 316 stainless steel flanges?

A: 304 stainless steel (ASTM A182 F304) offers good general corrosion resistance and is cost-effective, suitable for food processing and general industrial use. 316 stainless steel (ASTM A182 F316) contains molybdenum, providing superior resistance to chlorides, pitting, and crevice corrosion, making it ideal for marine, chemical, and pharmaceutical environments.

Q3: What is the difference between Weld Neck and Slip-On flanges?

A: Weld Neck Flanges (WN) have a long tapered hub for stress distribution and are suitable for high-pressure, high-temperature critical applications. 

Slip-On Flanges (SO) are slid over the pipe and welded both inside and outside, offering easier alignment and lower cost, but are generally used for low-pressure, less critical systems.

Q4: What pressure ratings and facing types do you offer?

A: Our flanges are available in Class 150 / 300 / 600 / 900 / 1500 / 2500 (ASME) and PN6 ~ PN100 (EN). Facing options include Flat Face (FF) for low pressure, Raised Face (RF) as standard, Ring Type Joint (RTJ) for high-pressure/high-temperature, and Tongue & Groove (T&G) or Male & Female (M&F) for critical sealing applications.

Q5: What is the difference between Duplex 2205 and 316 stainless steel flanges?

A: Duplex 2205 (ASTM A182 F51) offers approximately double the yield strength of 316 (450 MPa vs 205 MPa) and provides superior resistance to chloride stress corrosion cracking and pitting. It is preferred for offshore platforms, chemical tankers, and high-stress chloride environments. 316 stainless steel is more cost-effective for most marine and chemical applications.

Q6: What is passivation and why is it important?

A: Passivation is a chemical treatment that removes free iron and surface contaminants from stainless steel, restoring the natural corrosion-resistant oxide layer. It improves corrosion resistance, prevents rust staining, and creates a clean surface suitable for food, pharmaceutical, and sanitary applications. Passivation per ASTM A967 is available upon request.

Q7: What is the difference between pickling and passivation?

A: Pickling is an acid bath treatment that removes heavy scale, welding discoloration, and surface impurities, resulting in a matte grey finish. It is used to clean the surface after welding or heat treatment. Passivation is a milder chemical treatment that removes free iron and restores the oxide layer for enhanced corrosion resistance — it is the final step for surface protection.

Q8: What is your minimum order quantity (MOQ) and delivery time?

A: For trial orders, our MOQ is 10 pcs per size. For bulk orders, MOQ is flexible. 

Delivery time is 7-15 days for standard sizes in stock after payment confirmation. Custom orders typically require 20-30 days, depending on specifications.

Q9: How do you control quality?

A: We implement strict 3-stage quality control: raw material verification by spectrometer, production dimensional checks during forging and machining, and final inspection covering dimensions, bolt hole alignment, facing finish, hardness, PMI (positive material identification), and surface condition. A Mill Test Certificate (EN 10204 Type 3.1) is provided with every shipment.

Q10: Do you accept OEM or custom orders?

A: Yes, we accept custom orders based on your drawings, specifications, or samples. We can also apply your logo on products and packaging. 

Our engineering team will review your requirements and provide a solution within 24 hours.