fabrication and quality control of structural steel

1

Fabrication definition

Fabrication is the second main process in steel lifecycle after production from mills.

2

Difference bet. Q.C & Q.AQuality control: activities used to fulfill requirements

for quality. (ex: calibration)

“Quality control is a process for maintaining standards and not for creating them.”

Quality assurance: activities that do not control quality but establish the extent to which quality will be.(ex: statistical control)

3

Main raw materials Standard sections

Plates

Fasteners

Weld electrodes

4

Main procedures• Receiving ,

storage, identification and traceability of raw materials.

• Preparation of material.

• Production.• Surface

preparation & protection.

5

1.Receiving , storage, identification and traceability of raw materials

6

1.Receiving , storage, identification and traceability of raw materials

Color Coding Printed Heat No.

Hard Stamp

7

2.Preparation of material

Material is prepared for bolting (in site) or welding (in next stage) by:

Cutting of steel elements.

Edge preparation.

Holes drilling or punching.

Rolling of plates.

8

2.Preparation of material

Hole Punching Hole Drilling9

3.Production Cold forming: using bend machine

10

Welding (main process)Factors affecting quality of weld:

1-Proper electrode

2-Welding apparatus

3-Welding method

4-Welding position

5-Edge preparation

6-Control of distortion

11

Welding (main process)Possible defects in weld:

1-Lack or incomplete fusion.

2-Inadequate edge preparation.

3-Porosity and gas pockets.

4-Undercut.

5-Slag inclusion.

6-Cracks.

12

Non-destructive testsRadiography test(RT): used for small thicknesses to show the defects

inside weld .It uses x-rays and gamma rays.

Ultrasonic test (UT): using ultrasonic waves, used for large thicknesses, it’s faster and easier for judgment and need one technician to be carried out but it needs a certified and qualified technician.

Magnetic Test (MT): using magnet to identify subsurface defect up to 6 mm below surface for A.C current or up to 4 mm below surface for D.C current.

It must be used with materials that have magnetic properties.

Dye penetrant test (PT): used for identifying surface defects or subsurface but open to surface.

As red spot gots wider as defect is deeper.

13

MT device Plan of weld

14

4.Surface preparation & protection

Methods of preparation:

-Wire brush (manual or automatic)

-Blasting using : - Sand

- Marble

Methods of protection:

-Painting: primer layer followed by another epoxy layer

-Galvanization: for higher protection requirements

15

Refrences

Egyptian code of practice for steel construction and bridges.

AISC structural steel building specifications.

16