FAQ

Yes, we are a stainless steel flange manufacturer. Long'an Flange specializes in manufacturing various types of stainless steel flanges and customizing non-standard products.

Our pricing is based on quality advantages at the same price point.

Yes, we provide certifications. We have obtained many domestic and international certifications, including CE, Quality Management System, and Environmental Management System certifications.

We accept Letter of Credit (L/C), Telegraphic Transfer (T/T), and Document against Payment (D/P) as payment methods.

When you buy forged flange parts, you don't have to buy a certain amount. But if you want a length that's more than 2 meters, you'll need to buy at least 10 pieces.

It usually takes us 2 to 4 weeks to make your order, but it depends on how complicated it is and how busy we are.

Yes, we offer OEM services as an experienced stainless steel flange manufacturer, specializing in customized non-standard flanges.

We package our big, heavy flanges in wooden crates and the small, light ones in cardboard boxes. The choice depends on what kind of flange it is, its size, weight, and how far it needs to be transported.

We offer many ways to ship your items, like by truck or boat. We'll find the best way for you based on your needs.

As a stainless steel flange manufacturer, we mainly produce flanges from stainless steel grades such as 304, 304L, 316L, duplex 2205, and super duplex 2507. We can also work with other special materials based on application requirements and customer specifications.

Longan Flange produces approximately 10,000 tons of stainless steel flanges per year. Our facility operates 160 high-precision machining centers and 150 testing instruments, enabling Longan Flange to handle both large-volume orders and single-piece custom projects with consistent quality.

Longan Flange was founded in 2011 in Wenzhou, Zhejiang Province, China. As a dedicated stainless steel flange manufacturer with over 13 years of experience, Longan Flange serves EPC contractors, wholesalers, and OEM buyers across 50+ countries worldwide.

Yes. As a vertically integrated stainless steel flange manufacturer, Longan Flange performs all forging, machining, and inspection under one roof at our Wenzhou facility. We do not outsource any production step, which gives Longan Flange full traceability from raw billet to finished product and complete control over quality and delivery.

Longan Flange is a stainless steel flange manufacturer in China, with its factory located at 620 Kongo Mingzhu Road, Yongxing Street, Longwan District, Wenzhou City, Zhejiang Province, China. Longan Flange welcomes factory visits and on-site audits by appointment.

As a full-range stainless steel flange manufacturer, Longan Flange produces all major flange types, including Weld Neck (WN), Slip-On (SO), Blind (BL), Threaded (TH), Socket Weld (SW), Lap Joint, and Plate (Flat) flanges, as well as custom large-diameter flanges up to DN4000. Longan Flange also produces non-standard products such as tube sheets, filter flanges, pressure vessel flanges, PTFE-lined flanges, and radar-mounting flanges.

Longan Flange's standard grades include SS304, 304L, 316L, duplex 2205 (F51), super duplex 2507 (F53), TP310S, and TP321. For other special material requirements, contact Longan Flange with your specifications and our engineering team will confirm availability.

Longan Flange manufactures flanges to ASME B16.5, DIN, GOST, JIS, GB/T, BS, and API standards. Specific standards include ASME B16.5 (Class 150–2500), GB/T9119, HG/T20592, HG/T20615, DIN 2576, and GOST 12820. Longan Flange's multi-standard capability ensures compatibility with piping systems worldwide.

Longan Flange's standard flanges range from DN15 to DN600. For large-diameter and custom flanges, Longan Flange can manufacture up to DN4000 (4 meters in diameter) — making Longan Flange one of the few stainless steel flange manufacturers capable of this size range.

Longan Flange covers a full range of pressure classes depending on flange type and standard. For ASME B16.5 weld neck flanges: Class 150 through Class 2500. For slip-on flanges: Class 150 through Class 1500. For DIN/GOST plate flanges: PN2.5 through PN25 (PN40 available on request). Contact Longan Flange with your pressure and temperature requirements for specific recommendations.

Every flange produced by Longan Flange goes through a multi-stage inspection process: raw material spectral analysis to verify chemical composition, dimensional measurement during and after machining, hardness testing, pressure testing, and non-destructive testing (NDT). Longan Flange maintains full material traceability from billet to shipment.

Yes. Every flange produced by Longan Flange ships with a material test report documenting chemical composition, mechanical properties, and inspection results. Longan Flange's quality process includes NDT, hardness testing, and full material traceability from raw billet to finished product.

Longan Flange performs Ultrasonic Testing (UT) and Penetrant Testing (PT) as part of our standard quality inspection process. The specific NDT scope is determined based on product type, applicable standard, and customer specifications. Contact Longan Flange to discuss your NDT requirements for a particular order.

Yes. Longan Flange welcomes third-party inspection and has experience coordinating with agencies including SGS and TÜV. Buyers are responsible for inspection fees and can arrange TPI through their preferred agency. Please inform Longan Flange of your TPI requirements when placing the order so we can coordinate the inspection schedule accordingly.

Longan Flange provides quotes within 24 hours from drawing review to pricing, for both standard and custom orders. Simply send your specifications to our sales team and Longan Flange will respond with detailed pricing and lead time.

Longan Flange ships from Shanghai Port and Ningbo Port, two of China's largest and most well-connected shipping hubs. Our logistics team arranges the most efficient route based on your destination and preferred shipping method.

As a stainless steel flange manufacturer serving global markets, Longan Flange's products are widely used in oil & gas, petrochemical, chemical processing, power generation, water treatment, food processing, pharmaceutical, shipbuilding, HVAC, and large infrastructure projects. Longan Flange's product range and multi-standard compliance make us a reliable supplier for EPC projects across all major industrial sectors.

SS304/304L is suitable for general-purpose applications with moderate corrosion resistance. SS316L contains molybdenum, which provides significantly better resistance to chloride corrosion and pitting — making it the preferred choice for chemical plants, marine environments, and applications involving acids or saltwater. Longan Flange recommends 316L for any operating environment involving chlorides or aggressive media. Contact Longan Flange's engineering team for material selection guidance on your specific application.

Duplex 2205 offers roughly twice the yield strength of standard austenitic grades (304/316L) along with superior chloride stress corrosion cracking resistance. It is commonly specified for offshore platforms, desalination plants, and chemical process piping. Super duplex 2507 provides even higher strength and corrosion resistance for the most demanding environments, such as subsea pipelines and high-chloride chemical processing. Longan Flange manufactures both duplex 2205 (F51) and super duplex 2507 (F53) flanges in all major types and sizes.

Forged flanges are made by shaping solid steel under high pressure, resulting in a denser grain structure, higher mechanical strength, and better resistance to fatigue and impact. Cast flanges are poured into molds and may contain porosity or inclusions. All Longan Flange products are forged in-house at our Wenzhou facility, ensuring consistent structural integrity and reliability for critical piping systems.