Plate Flange/PL Flange

What is Plate flange?

Plate flanges are made by cutting from a flat steel plate, usually carbon steel or stainless steel. After that, they are machined to precise dimensions, including the bolt holes and the center bore. Unlike forged flanges, which are shaped under high pressure, these flanges begin simply as a flat piece of metal.
More detail difference about plate flange and forged flange, please click here.

Because they aren’t forged, plate flanges are simpler and more economical to produce. They are typically welded directly to a pipe, which is why they’re often called welded plate flanges. This makes them especially well-suited for lower-pressure applications where extreme strength isn’t required.

Common uses pressure applications up to 300 psi in piping systems, water and gas pipelines, and a range of general industrial applications.

Applications of Plate Flanges:

• Low-Pressure Piping Systems
• Municipal Water Pipelines
• Industrial Gas Pipelines
• Ventilation and Exhaust Lines
• Structural Utility Connections

Specification

Plate Flange Standards

What are the plate flange Advantages?

Plate flanges have several advantages, such as:
Easy to Manufacture: Plate flanges can be easily manufactured by cutting and shaping a flat plate.
Cost-Effective: Plate flanges are relatively inexpensive compared to other types of flanges, making them a cost-effective option.
Customizable: Plate flanges can be customized to suit specific application needs, such as different pressure ratings and sizes.

Frequently Asked Questions

What is a plate flange?
A plate flange is a flat, circular metal component which made from carbon steel, stainless steel, or alloy steel. They are used to connect pipes, valves, pumps, or other equipment in a piping system.

What’s the difference between a plate flange and a forged flange?
A plate flange is cut from a flat metal plate and then machined, while a forged flange is shaped under high pressure to improve strength. Plate flanges are generally for lower-pressure systems.

Where are plate flanges most often used?
In water pipelines, irrigation systems, low-pressure gas lines, and various industrial applications where cost savings and simplicity are key.

Where are plate flanges not suitable?
They’re generally not used in high-pressure or critical service lines where forged or weld neck flanges are required.

Why choose JSFITTINGS as your plate flange supplier?

1. 30,000-ton production capacity guarantee | Stable supply of large-scale project needs
2. Dual-standard certified steel pipes | API 5L + EN 10219 dual compliance assurance
3. Precision Cutting Services | Ready-to-use pipe end treatments
4. Oil and Gas Project Logistics System | Exclusive Shipping Solutions Covering Central Asia/Middle East

1. Dimensional & Visual Inspection

1.1 Dimensional Tolerance Checks (Per ASTM A530 / API 5L)
Parameter Tolerance Instrument Used
Outer Diameter (OD) ±1% of nominal OD (or ±0.79mm) Pi tape / Laser micrometer
Wall Thickness (WT) ±12.5% (SCH40 and below) Ultrasonic thickness gauge (UTG)
Length ±3mm for random, ±6mm for cut-length Calibrated tape measure
Straightness ≤0.2% of total length Optical comparator
Bevel Angle (for welding) 30°–35° (±5°) Bevel protractor
1.2 Visual & Surface Inspection
Defect Identification:
Lamination – Check for delamination near pipe ends
Scratches/Dents – Max 5% of WT depth allowed (per ASME B31.3)
Rust & Mill Scale – Controlled by SSPC-SP6 (Commercial Blast Cleaning)
Method:
White light inspection (10,000 lux minimum)
Dye penetrant test (PT) for surface cracks

2. Mechanical & Chemical Testing.

2.1 Chemical Composition (Per ASTM A751)
Spark OES Analyzer (for C, Mn, Si, P, S, Cr, Mo, etc.)
LECO Gas Analyzer (for O₂, N₂, H₂ in high-purity applications)
Sampling: Drill chips from mid-wall section (avoiding decarburization)
2.2 Mechanical Properties
Test Standard Equipment Acceptance Criteria
Tensile Test ASTM A370 Universal testing machine ≥415 MPa (A106 Gr.B)
Hardness Test ASTM E10/E18 Rockwell/Brinell tester ≤187 HB (A106 Gr.B)
Impact Test (Charpy V) ASTM A370 Pendulum impact tester ≥27J @ -20°C (API 5L X42)
Flattening Test ASTM A53 Hydraulic press No cracking @ ⅔ WT flattening
Drift Expanding Test API 5L Mandrel expansion tool No cracks @ 8% expansion
(Note: A106 requires extra tensile tests at elevated temps for high-temp service)

3. Non-Destructive Testing (NDT)

3.1 Ultrasonic Testing (UT)
Method: Automated rotating UT probes (ASTM E213)
Detection Capability:
Laminations: ≥5% of WT
Inclusions: ≥2mm diameter
Scanner Type: Immersion tank UT for full-body coverage
3.2 Radiographic Testing (RT)
Standard: ASTM E94 (Film/Digital RT)
Sensitivity: Detect 2% WT lack of fusion in welds
Application:
Mandatory for ERW weld seams (API 5L)
10% random sampling for seamless pipes
3.3 Eddy Current Testing (ECT)
Used for surface crack detection in thin-walled pipes (SCH10 and below)
Advantage: No couplant, fast scanning speed (30m/min)
3.4 Hydrostatic Test
Pressure: Minimum 1.5x design pressure (ASME B31.3)
Duration: ≥10 sec (ASTM A106)
Leak Criteria: Zero visual weeping

4. Specialized Tests for Critical Applications

4.1 Corrosion Testing
Salt Spray Test (ASTM B117): 720h exposure for coastal projects
HIC Test (NACE TM0284): Hydrogen-induced cracking resistance for sour service
SSC Test (NACE TM0177): Sulfide stress cracking evaluation
4.2 High-Temperature Performance
Creep Rupture Test (ASTM E139): 10,000h data available for A106 Gr.B
Cyclic Oxidation Test: Weight loss measurement at 600°C