Plate Flat-Weld Flange engineering specification

Plate Flat-Weld Flanges (PL) are flat-disc pipe connectors without a hub, used for low-pressure utility service. As a Chinese plate flange manufacturer and supplier, we produce PL flanges to GB/T 17241.6 (China national), HG/T 20592-2009 PN 6 to PN 25 (1.5 to 6.5 bar), GOST 12820 (Russia), and JB/T 81 (Chinese machinery). EN 1092-1 Type 01 (Plate flange) is the European equivalent.

Plate flanges are the simplest and most economical flange type. They have no hub (flat disk) and are fillet-welded to the pipe at the outside diameter only. Plate flanges are produced from hot-rolled or cold-rolled steel plate by flame or plasma cutting, then machined on the gasket face and bolt circle.

Plate flanges are limited to PN 6 – PN 25 (Class 150 equivalent) and temperatures up to 200°C. For higher pressure or temperature, Slip-On (SO) or Weld Neck (WN) flanges are preferred due to better hub stress distribution. ASME B16.5 does not have a "Plate flange" type, the closest equivalent is a flat-face Slip-On flange.

Common applications: water treatment, HVAC, building services, low-pressure chemical lines, agricultural irrigation, fire-protection mains, utility water distribution. Plate flanges are the standard specification for low-pressure utility and HVAC piping in Asia and the Middle East.

Materials: Q235A Chinese carbon steel (default), 20# carbon steel, 16MnDR low-temperature carbon steel, 304/316 stainless steel. All supplied with EN 10204 3.1 mill certificate. ISO 9001:2015 quality management. PED CE-marking available on request for EN 1092-1 plate flanges.

Manufacturing: Plate flanges can be produced by stamping (for thin plates, ≤ 6mm), laser-cutting (for precision), or flame-cutting (for thick plates). The gasket face and bolt circle are machined on CNC vertical turning lathes. Surface finish Ra 3.2-6.3 μm (125-250 μin) for RF (raised face).

Pressure-temperature rating per HG/T 20592-2009: PN 6 (6 bar / 87 psi) for water and utility service. PN 10 (10 bar / 145 psi) for chilled water and building services. PN 16 (16 bar / 232 psi) for low-pressure chemical lines. PN 25 (25 bar / 363 psi) is the maximum standard rating for plate flanges. Above PN 25, use Slip-On (SO) or Weld Neck (WN) flanges.

Applications: water treatment and distribution (municipal water mains, treatment plant piping), HVAC (chilled water, condenser water, cooling tower headers), fire-protection mains, agricultural irrigation, low-pressure chemical transfer, building services (booster pump headers, air handler connections). Plate flanges are the standard specification for low-pressure utility service in Asia and the Middle East.

Comparison to ASME: ASME B16.5 does not have a "Plate flange" type, the closest equivalent is a flat-face Slip-On (SO) flange. For international projects, EN 1092-1 Type 01 is the direct equivalent. Chinese HG/T 20592 PL flanges and EN 1092-1 Type 01 are dimensionally interchangeable for PN 6 to PN 25.

Manufacturing cost: Plate flanges are 30-40% cheaper than Slip-On (SO) flanges and 50-60% cheaper than Weld Neck (WN) flanges due to less machining and no forging. For large-bore service (NPS ≥ 24), plate flanges are the most economical choice.

Shipping: Standard NPS 1/2"–24" PL flanges in Q235A ship in 10–15 days from order confirmation. Non-stocked sizes, stainless materials (304/316), or low-temperature 16MnDR ship in 25–40 days. Sea freight from Shanghai / Tianjin to major ports in 14–30 days. Third-party inspection by SGS / BV / TUV / Intertek available on request.