Plate type flat welding flange, abbreviated as PL flange, is the most cost-effective and convenient pipeline connection flange in the domestic HG/T20592 and GB/T9112 national standard systems. With the advantages of plug-in corner welding, no need for pipeline groove welding, and low cost, it has become the most commonly used flange category in low-pressure and room temperature pipeline networks. Many procurement and engineering technicians often confuse the usage boundaries of plate welding flanges and neck welding flanges. This article combines domestic industrial standards to explain in detail the industry scenarios, applicable working conditions, and prohibited scenarios where plate welding flanges are most commonly used, in order to accurately avoid selection errors. At the same time, Shanghai Hongguan Stainless Steel Flanges provide various materials of flanges. Welcome to inquire!

1、 Top 4 industries in terms of usage of flat welding flanges (concentrated usage, preferred for rigid needs)

1. Municipal water supply and drainage industry (ranked first in national usage)

The municipal industry is the largest application area for flat welding flanges, which are fully compatible with urban water supply pipelines, municipal sewage and rainwater pipelines, pump station units, water plant clean water pipelines, and outdoor fire protection pipelines. The working conditions are uniformly PN10 and PN16 low pressure levels, with room temperature clean water and sewage media. The pipeline vibration is minimal and the pressure fluctuation is stable. Almost all large-diameter pipelines (DN300-DN2000) use carbon steel plate flat welding flanges, which have low construction costs and high welding efficiency, and are suitable for large-scale municipal pipeline construction.

2. Chemical industry utility system (preferred low-pressure flange for chemical industry)

The chemical industry strictly prohibits the use of flat welding flanges for flammable and explosive process pipelines, but the public engineering systems in the factory area have a large amount of usage and are also standard low-pressure flanges in the chemical plant area. Mainly used for chemical circulating water pipelines, equipment cooling water, desalinated water, factory exhaust gas ventilation pipelines, workshop sewage discharge, non hazardous neutral material transportation pipelines, compatible with HG/T20592 chemical special plate flat welding flanges, only used for atmospheric pressure, low pressure, non-toxic, and non permeable medium pipelines. The use of high-risk process pipelines is prohibited.

3. HVAC+Building Fire Protection Industry

Industrial parks, commercial buildings, factory HVAC systems, chilled water, cooling water, fresh air ventilation pipelines, indoor and outdoor fire water supply pipelines, and large-scale use of PN16 plate flat welding flanges. The medium temperature is stable, the pressure is constant, and there is no severe vibration. Paired with ordinary rubber gaskets and PTFE gaskets, it can meet the sealing requirements, while balancing procurement costs and installation efficiency. It is a standard flange in the HVAC and fire protection industry.

4. Thermal power environmental protection water treatment industry

Water replenishment pipelines, desulfurization and denitrification ash water pipelines, and dust removal air ducts in thermal power and thermal power plant areas; The biochemical tank pipeline, ultrafiltration reverse osmosis atmospheric pressure pipeline, and reclaimed water reuse pipeline of the sewage treatment plant all use plate type flat welding flanges in bulk. The working conditions are low pressure and room temperature, and the medium is weakly corrosive. The use of stainless steel plate flat welding flanges can meet the anti-corrosion requirements, replacing expensive neck welding flanges and effectively controlling project costs.

2、 General adaptation conditions for flat welding flanges of plate type (selection criteria)

Adaptation standards:HG/T20592 Chemical Plate Flat Welding Flanges, GB/T9119 National Standard Plate Flat Welding Flanges

Adaptation pressure:Only for PN6, PN10, PN16, up to PN25

Suitable temperature:-Under normal temperature conditions of 20 ℃~150 ℃, overheating is prohibited

Adaptation medium:Clear water, sewage, air, circulating water, neutral and weakly corrosive media, non-toxic and odorless non hazardous media

Adaptation environment:Pipeline vibration is small, pressure is stable, there is no negative pressure vacuum, and there is no impact pressure pipeline

3、 Plate welding flanges are absolutely prohibited under industry conditions (engineering red line)

1. Chemical process pipelines: methanol, liquid chlorine, aromatic hydrocarbons, flammable and explosive, toxic and permeable medium pipelines. PL plate flat welding flanges are prohibited and WN neck welding flanges must be selected;

2. High temperature and high pressure pipelines: Steam above 150 ℃, heat transfer oil, high-pressure process gas, and hydrogen pipelines are strictly prohibited from use;

3. Export of power equipment: Vibration pipelines for inlet and outlet of water pumps, compressors, and fans are prohibited from use;

4. Equipment nozzle docking: For the nozzles of reaction vessels, storage tanks, and tower pressure vessels, NB/T47020 pressure vessel flanges are required, and plate welding pipe flanges cannot be mixed;

5. Vacuum pipelines and high sealing explosion-proof pipelines are prohibited from using plate type flat welding flanges throughout the entire process.

4、 Why is flat welding flange preferred in the low-voltage industry?

1. High cost-effectiveness: The price is only 50% -60% of the neck welding flange, significantly reducing procurement costs for large-scale projects;

2. Simple construction: Double sided corner welding is sufficient for pipeline insertion, without the need for groove processing or non-destructive testing, shortening the construction period;

3. Strong universality: RF protruding surface sealing is the main feature, gasket selection is simple, national chemical standards are interchangeable, and stocking is convenient.

Article Summary

Plate welding flanges are most commonly used in three industries: municipal water supply and drainage>chemical public engineering>HVAC fire protection and environmental protection. The core positioning is low-pressure, room temperature, non hazardous, small vibration, and cost controllable pipeline network. As long as high temperature, high pressure, toxic, flammable and explosive conditions, and pressure vessel docking conditions are avoided, PL plate flat welding flanges can be used with confidence.