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Steel Structure Welding: A Complete Table Of NDT Methods, Testing Percentages & Weld Positions

Apr 02, 2025

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steel structures welding

Background

 

Steel structure construction has become increasingly prevalent worldwide due to its versatility and efficiency. Welding plays a critical role in steel fabrication, ensuring robust connections between components while enhancing structural integrity and stability. This article examines key welding requirements, quality classifications, and inspection methodologies for steel structures.

 

Table of steel structure welding position, NDT methods, and testing percentages

 

Factory welding

Weld Joints Location

Welding requirements

Welding Grade

NDT Methods

Inspection Percentage

Steel plate and structural member splicing and extension

Groove full penetration butt weld

Grade I

UT

100%

Horizontal stiffener (or Diaphragm) at beam flange connections to cross-shaped column

Connected to column flange

Full penetration T-joint

Grade II

UT

20%

Connected to column web

Fillet weld

Grade III

MT

10%

Horizontal stiffeners (or Diaphragm) at H-column / I-column connections

Beam-column strong-axis rigid connection

Connected to column flange

Full penetration T-joint

Grade II

UT

20%

Connected to column web

Fillet weld

Grade III

MT

10%

Beam-column weak-axis rigid connection

Connected to column web plate

Groove full penetration butt weld

Grade I

UT

100%

Box steel column horizontal stiffeners ( or diaphragms)

Connected to column wall

Full penetration T-joint or electroslag weld

Grade II

UT

20%

Connected to beam/ column wall

Fillet weld

Grade III

MT

10%

Combined welds between column wall plates

Beam-column joint & 500mm above/below

Full penetration groove weld

Grade I

UT

100%

100mm above/ below the column joint

Full penetration groove weld

Grade I

UT

100%

Outside the full penetration zone

Box steel column

Four corners

Partial penetration groove weld

Grade II

UT

20%

I column

Web, flange

Fillet weld or partial K-groove weld

Grade II

UT

20%

Cruciform column

Web, flange

Partial K-groove weld

Grade II

UT

20%

Reinforcement plate to beam web when beam web has a hole

Fillet weld

Grade III

MT

10%

High-rise steel structure brace connections & frame beam-column joint

Full penetration groove weld

Grade I

UT

100%

Multi-story steel structure brace connections & frame beam-column joint

Full penetration groove weld

Grade II

UT

20%

Hanger column-to-beam flange

Full penetration groove weld

Grade I

UT

100%

On-site installation welding

Beam-column fully welded rigid joint

Beam flange

Full penetration groove weld

Grade I

UT

100%

Beam web

Fillet weld

Grade III

MT

10%

Beam-to-column bolted-welded hybrid rigid connection (beam end flange with reinforcement cover plate)

Beam flange

Full penetration groove weld

Grade I

UT

100%

Cover plate to beam flange

Fillet weld

Grade III

MT

10%

Cantilevered beam segment in steel column to frame beam bolted welded hybrid rigid connection

Beam flange

Full penetration groove weld

Grade II

UT

20%

Column-to-column

I-column bolted-welded hybrid connection

flange

Full penetration groove weld

Grade I

UT

100%

I-column fully welded connection

flange

Full penetration groove weld

Grade I

UT

100%

web

Upper column with K-groove full penetration weld

Grade II

UT

20%

Box column

Wall plate

Upper column with full penetration groove weld

Grade I

UT

100%

Box column and cross-shaped steel column

Transition section wall plate

Upper column with full penetration groove weld

Grade I

UT

100%

Variable section column

Wall plate, diaphragm to wall plate

Upper column with full penetration groove weld

Grade I

UT

100%

Secondary beam to the main beam bolted-welded hybrid rigid connection

flange

Full penetration groove weld

Grade II

UT

20%

Gusset plate to brace

Fillet weld

Grade III

MT

10%

Reinforcement plate to beam web when beam web has a hole

Fillet weld

Grade III

MT

10%

Column to base plate

Full penetration butt and fillet weld combination

Grade II

UT

20%

Beam end flange to support or embedded part rigid connection

Full penetration butt and fillet weld combination

Grade II

UT

20%

Cantilever beam root to support / embedment

Full penetration butt and fillet weld combination

Grade I

UT

100%

Multi-story steel structure central brace to gusset plate

Fillet weld

Grade III

MT

10%

Eccentric brace to energy dissipation segment

Full penetration groove weld

Grade II

UT

20%

Concealed steel plate shear wall bottom connection

Full penetration groove weld

Grade II

UT

20%

 

What is a complete joint penetration weld?

 

A complete joint penetration (CJP) weld, also called a full penetration weld, is the highest quality requirement in the welding of steel structure, which means that the weld metal completely melts through the entire joint thickness, realizes the complete fusion between the base material. This creates a strong, continuous bond across the entire joint, making it ideal for high-load and structural applications.

 

What is a fillet weld?

 

Fillet welds are triangular cross-section joints formed between perpendicular or angled metal components, typically used to transfer shear loads in structural connections. As the most common and cost-effective weld type in steel structure, they require precise control of leg size and throat thickness to ensure structural integrity.