Flange

Materials

Carbon Steel:
ASTM A105 – Standard specification for forged carbon steel piping components
ASTM A350 LF2 – For low‑temperature service (down to –50°C)

Stainless Steel (ASTM A182):
F304 / F304L
F316 / F316L
F321 (equivalent to GB/T S32168)
F347

Alloy Steel (ASTM A182): F1, F5a, F9, F11, F12, F22, F91.

Chinese Standard Materials (GB/T)

20# steel – equivalent to ASTM A105
Q355 – replaces 16Mn
S32168 – replaces 1Cr18Ni9Ti and 0Cr18Ni9Ti

Pressure Ratings & Size Ranges

We produce flanges in both PN (European) and Class (American) systems.
Class Series (per ASME B16.5 / B16.47): Class 150, 300, 400, 600, 900, 1500, 2500.
PN Series (per EN 1092‑1 / HG/T 20592): PN2.5, PN6, PN10, PN16, PN25, PN40, PN63, PN100, PN160, PN250, PN320, PN400.

Available Sizes by Standard

ASME B16.5: NPS ½" – 24" (DN15 – DN600) – for all five flange types listed above.
ASME B16.47: NPS 26" – 60" (DN650 – DN1500) – available for Blind flanges only (Series A or B).

Manufacturing Standards

We produce flanges to the following specifications:

ASME B16.5 – Pipe Flanges and Flanged Fittings (NPS ½ – 24)
ASME B16.47 – Large Diameter Steel Flanges (NPS 26 – 60) – Series A & B (for Blind flanges)
EN 1092‑1 – European standard for PN flanges (replaces most DIN standards)
HG/T 20592 – PN series (European system)
HG/T 20615 – Class series (American system)
JIS B2220, BS 4504, SABS 1123, UNI, AS 2129, GOST 12820 – available on request

Note: DIN standards are largely superseded by EN 1092‑1; we can supply either standard as required.

Detailed Descriptions of Each Flange Type

1. Slip‑On Flange (SO)

Slides over the pipe; fillet‑welded both inside and outside

Easier to align and less expensive than Weld Neck flanges, but lower fatigue strength

Suitable for general service, low‑ to medium‑pressure applications

Pressure classes: 150 – 600 only

No pipe schedule required – bore size is typically 1/16" larger than pipe OD

Standards: ASME B16.5, EN 1092‑1, HG/T

2. Blind Flange (BL)

Solid disc with bolt holes but no centre opening

Used to seal the end of a pipe, valve, or pressure vessel opening

Withstands high internal pressure and provides easy access for inspection

Pressure classes: 150 – 2500

Standards: ASME B16.5, B16.47 (large diameter), EN 1092‑1, HG/T

3. Socket Welding Flange (SW)

Socket Welded Flange Face TypesPipe inserted into socket; fillet‑welded around the top

Used for small diameters (NPS ½ – 4) and high‑pressure systems

Provides good leakage resistance and fatigue strength

Pressure classes: 150 – 600

Standards: ASME B16.5 (up to NPS 4), HG/T 20592/20615

T&G (Tongue and Groove Face)

4. Threaded Flange (TH)

Internal threads (NPT or BSP) allow connection to threaded pipes without welding

Ideal for galvanized piping or where welding is not permitted (e.g., explosive environments)

Not recommended for severe temperature cycling or high vibration

Pressure classes: 150 – 600

Standards: ASME B16.5, EN 1092‑1, HG/T

5. Lap Joint Flange (LJ / LJO)

Specification of Lap Joint FlangesUsed with a stub end (lap joint stub); flange rotates freely, facilitating bolt alignment

Lower cost because the flange material need not contact the process fluid

Typically used in low‑pressure, non‑critical services where frequent dismantling is required

Pressure classes: 150 – 600

Standards: ASME B16.5, EN 1092‑1, HG/T
Alloy Steel Flange: ASTM A182 F1, F5a, F9, F11, F12, F22, F91, A182F12, A182F11, 16MnR, Cr5Mo, 12Cr1MoV, 15CrMo, 12Cr2Mo1, A335P22, St45.8/Ⅲ;

Differenet faceing on flange

Raised Face Flange (RF)

Flat Face Flange (FF)

Ring Type Joint (RTJ)

Tongue and Groove (T/G)

Usage of pipe flange

For pipe connection
Pipe flanges are used to connect a series of pipes for water system.

For connecting valve
Pipe flanges are used to connect valves to control the flow within a water system.

To conect pump

To integrate pump to power the flow of water in line.

Packaging & Marking

Each flange is clearly marked per MSS SP‑25 with:

Manufacturer name or trademark;
Material grade (e.g., A105, F316L);
Nominal size (NPS or DN);
Pressure class (e.g., Class 150, PN16);
Standard conformance (e.g., ASME B16.5);
Heat number (for traceability);
Packaging: Wooden crates or pallets, with rust‑proof wrapping suitable for sea freight.



Custom Orders

We welcome custom designs – including non‑standard sizes, special materials, or unusual facing requirements. Please send your detailed drawings or specifications, and our engineers will provide a prompt quotation.