Factory-direct forged slip-on, weld neck, blind, and custom flange solutions engineered for critical piping networks.
A definitive guide for procurement directors, piping engineers, and global EPC contractors navigating Japanese Industrial Standard (JIS) flange dimensional requirements, pressure ratings, and metallurgical selections.
Widely specified in JIS B2220 piping. The pipe slips inside the flange hub and is secured via internal and external fillet welds. Provides superior resistance to bending stress compared to plate-type flanges.
Designed with a long tapered hub that transitions smooth stress distribution into the pipe wall. Critical for high-pressure JIS 20K, 30K, and 40K severe cyclic, high-temperature, or sub-zero cryogenic systems.
Solid disc forgings without a center bore, manufactured to JIS B2220 parameters for sealing pressure vessel nozzles, pipe ends, or future tie-in points during hydrostatic pressure testing.
Standard engineering dimensional specifications for JIS 10K and 20K Slip-On Hubbed (SOH) and Blind (BL) forged steel flanges. Critical for pipe fitters and structural drafting.
| Nominal Size (DN) | Nominal Size (Inch) | Outer Diam (D) [mm] | 10K PCD (C) [mm] | 10K Bolt Holes (n × d) | 20K PCD (C) [mm] | 20K Bolt Holes (n × d) | Thickness (t) [mm] |
|---|---|---|---|---|---|---|---|
| DN15 | 1/2" | 95 | 70 | 4 × 15 | 75 | 4 × 15 | 12 / 14 |
| DN20 | 3/4" | 100 | 75 | 4 × 15 | 80 | 4 × 15 | 14 / 16 |
| DN25 | 1" | 125 | 90 | 4 × 19 | 95 | 4 × 19 | 14 / 16 |
| DN40 | 1-1/2" | 140 | 105 | 4 × 19 | 105 | 4 × 19 | 16 / 18 |
| DN50 | 2" | 155 | 120 | 4 × 19 | 120 | 8 × 19 | 16 / 18 |
| DN80 | 3" | 185 | 150 | 8 × 19 | 160 | 8 × 23 | 18 / 20 |
| DN100 | 4" | 210 | 175 | 8 × 19 | 185 | 8 × 23 | 18 / 22 |
| DN150 | 6" | 280 | 240 | 8 × 23 | 260 | 12 × 25 | 22 / 26 |
| DN200 | 8" | 330 | 290 | 12 × 23 | 305 | 12 × 25 | 22 / 28 |
| DN250 | 10" | 400 | 355 | 12 × 25 | 380 | 12 × 27 | 24 / 30 |
| DN300 | 12" | 445 | 400 | 16 × 25 | 430 | 16 × 27 | 24 / 32 |
| DN500 | 20" | 675 | 620 | 20 × 27 | 650 | 20 × 33 | 30 / 42 |
Analyzing macroeconomic factors, regional engineering adoption, and procurement intents driving global supply chains in 2025 and beyond.
With East Asia controlling over 80% of global commercial shipbuilding (Japan, South Korea, and China), JIS flange specifications (JIS B2220 / JIS F7805) remain mandatory across marine ballast water treatment system (BWTS), fuel line skids, and LNG dual-fuel engine retrofits. Procurement officers require Class NK, ABS, and DNV certified forgings to ensure vessel class compliance.
South East Asian refiners and Middle Eastern EPC contractors building Japanese-designed chemical complexes require heavy-duty JIS 20K and 30K high-integrity forged flanges. Procurement intent has shifted heavily toward verified low-temperature toughness (V-notch impact tested at -46°C) and corrosion-resistant alloys like duplex SUS318LN (S31803) and austenitic SUS316L.
Strict environmental standards (ISO 15848-1 fugitive emission compliance) mean buyers no longer accept cheap cast or low-grade forged alternatives. Modern buyers prioritize suppliers who provide computerized 3D coordinate checking, full mill traceability back to steel billets, and zero-defect raised face (RF) serration profiles.
How modern Chinese forged flange facilities leverage automated hydraulic forging, digital twin quality tracking, and localized raw material access to offer unmatched cost-performance metrics.
Eliminating human tolerance variations, multi-axis CNC vertical lathes machine flange faces, gasket grooves (RTJ/Tongue & Groove), and bolt hole patterns (PCD) to sub-millimeter tolerances (ISO 2768-m compliance), ensuring 100% plug-and-play fitment on job sites.
From direct-reading spectrometer (PMI) raw material validation to automatic ultrasonic flaw detection (UT) and magnetic particle testing (MT), every batch of forged JIS steel flanges is linked to a permanent heat number and detailed EN 10204 3.1 inspection certificate.
Direct integration with premier domestic steel mills (Baosteel, TISCO) combined with localized heat treatment furnaces drastically cuts production lead times. Global buyers achieve 15% to 30% total cost reduction compared to European or Japanese domestic sourcing without compromising material density or strength.
Real-world deployment of JIS flange configurations across offshore marine vessels, municipal power infrastructure, and chemical plants.
Challenge: Retitting a Japanese-built Floating Production Storage and Offloading (FPSO) vessel required replacement of corroded seawater cooling lines within a tight 21-day drydock window.
Solution: Rapid manufacture and air-freight delivery of 450 pcs of JIS 10K & 20K SUS316L Slip-On Hubbed (SOH) flanges with anti-pitting solution treatment and Class NK witness testing. Zero field re-works recorded.
Challenge: High-temperature steam bypass lines operated by a Japanese main EPC required custom forged JIS 30K Weld Neck (WN) flanges made from alloy steel SFV22 (equivalent to ASTM A182 F22).
Solution: Custom closed-die forging, normalized and tempered heat treatment, complete 100% radiography on weld ends, and precision serrated raised face machining (Ra 3.2-6.3 μm).
Challenge: Ultra-high purity (UHP) gas line skid systems required compact, high-integrity JIS 16K Blind and Threaded flanges manufactured from vacuum-melted SUS316Ti stainless steel.
Solution: Internal bore mechanical polishing, degreasing treatment, cleanroom ultrasonic washing, and individual vacuum protective packaging to eliminate hydrocarbon contamination.
Essential technical verification criteria to guarantee metallurgical compliance, mechanical performance, and authentic certification when procuring from overseas manufacturers.
Ensure the manufacturer utilizes solid forged bar stock or rolled rings with a minimum forging reduction ratio of 3:1. Avoid cheap flame-cut steel plate blanks which suffer from laminar inclusions and directional weakness under pressure.
Carbon steel (SF440A / A105) must undergo normalizing to refine grain boundaries. Stainless steel (SUS304 / SUS316L) requires full solution annealing at 1050°C followed by rapid water quenching to prevent chromium carbide precipitation at grain boundaries.
In accordance with JIS B2220 specifications, Stock Finish or Spiral Serrated raised faces (RF) must maintain a roughness between Ra 3.2 to 6.3 μm (125 to 250 AARH) with 45 to 55 grooves per inch to ensure proper gasket compression without tearing soft faces.
Never accept generic unverified mill test reports. Ensure each certificate lists exact heat numbers, chemical composition (C, Mn, Si, P, S, Cr, Ni, Mo), mechanical test results (tensile, yield, elongation, hardness), impact values, and NDT reports.
Expert responses to critical technical, dimensional, and logistics queries encountered by international buyers.
The 'K' in JIS standards stands for "Kgf/cm²" (kilogram-force per square centimeter), which represents nominal working pressure capability at ambient temperatures. For quick engineering conversion: 10K ≈ 10 kgf/cm² ≈ 0.98 MPa ≈ 142.2 PSI ≈ 9.81 Bar. Higher K-ratings (such as 20K, 30K, or 40K) signify thicker flange bodies, larger bolt circle diameters (PCD), and more robust bolting configurations designed for high-stress applications.
No, direct mating is generally impossible without a customized transition flange or adapter spool piece. Although JIS 10K, ASME Class 150, and DIN PN16 operate in similar pressure regimes, their Pitch Circle Diameters (PCD), outer diameters, and bolt hole quantities differ. For example, a DN80 (3") JIS 10K flange has 8 bolt holes on a 150mm PCD, while an ASME Class 150 3" flange has 4 bolt holes on a 152.4mm PCD. Forcing these connections creates severe bending stress on studs and guaranteed gasket seal failure.
Under JIS standards, raw material grades are designated specifically:
• Carbon Steel: SS400 (General structure), SF440A (Forged carbon steel for pressure vessels, equivalent to ASTM A105), S20C/S25C.
• Stainless Steel: SUS304, SUS304L, SUS316, SUS316L, SUS316Ti (High heat/acid applications).
• Alloy Steel: SFV22 (1.25Cr-0.5Mo), SFV3 (equivalent to ASTM A182 F11/F22).
• Duplex Steel: SUS318LN / S31803 (Offshore marine & desalination).
• SOP (Slip-On Plate): Flat plate flange slipped over the pipe and fillet welded. Economical, used in low-pressure (JIS 5K, 10K) utility lines.
• SOH (Slip-On Hubbed): Includes a reinforced forged hub that distributes mechanical stress away from the weld root. standard for medium-pressure piping.
• WN (Welding Neck): Features a long tapered hub butt-welded directly to the pipe. Superior resistance to fatigue, thermal shock, and bending loads.
• BL (Blind): Solid disc used to block off pipe ends or pressure vessel inspection ports.
Our engineering office accepts 3D CAD models (STEP, IGES) and 2D CAD drawings (DWG, PDF). Prior to forging, we perform Finite Element Analysis (FEA) and forging simulation to ensure die fill and grain alignment. Finished custom flanges undergo 100% CMM (Coordinate Measuring Machine) inspection to verify complex bore contours, special gasket tongue/groove tolerances, and PCD alignments before dispatch.
To withstand long sea voyages, we offer:
• Transparent rust-proof oil or light yellow varnish coating.
• Black anti-rust paint or epoxy resin coating.
• Hot-Dip Galvanizing (HDG) per ISO 1461 / JIS H8641 for harsh marine environments.
• Polyethylene end caps and vacuum foil wrapping for high-purity polished stainless steel flanges.
For standard JIS 10K and 20K sizes (DN15 to DN600) held as forged rough blanks in stock, finish machining and export packaging require 7 to 14 business days. Custom forgings or heavy sizes (DN700 to DN1500) typically require 20 to 30 days. We support low MOQ trial orders for distributors and stockists replenishment, as well as full container loads (FCL) for major EPC projects.
Every steel billet entering our plant is stamped with a unique heat code. This code is tracked through shearing, heating, ring rolling, heat treatment, and machining. Before packing, the heat number, brand logo, standard (JIS B2220), size, pressure rating, and material grade are hard-stamped on the flange outer rim, providing 100% material traceability matched to the EN 10204 3.1 Mill Test Certificate.
Complete range of standard and specialized OEM flange components ready for worldwide logistics distribution.
