Welding Basics

from-Bugphai.jpg

In this article, we will talk about the ff:

- types of joints

– types of welds,

– how to interpret weld symbols

 

Definition

Welding is the process of joining two or more pieces of metal by applying heat and/or pressure with or without filler metal, to produce a union through localized fusion of the substrates and solidification across the interface

 

Advantages

  • Simple joint design
  • Reduce the amount of materials and work sequence
  • Reduce the weight of components
  • High joint efficiency
  • Well air tightening
  • No limitation for joint thickness
  • Less noise during work

 

Disadvantages

  • Distortion due to the local heating/cooling by welding
  • Residual stress
  • Changes in metallurgical or mechanical property of the base metal
  • Propagation of the cracks
  • Difficult to dismantle

 

Types of Joints

types of joints

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Types of Welds

fillet weldsquare weld

bevel weld V-grooveJ-groove U-grooveflare-bevelflare v-groove

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Other Types of Welds

Plug or Slot Weld – are welds which partially or entirely fill the holes.

plug or slot weld

 

 

 

 

 

 

Side Seam Weld

side seam

 

 

 

 

 

 

 

Spot Weld – is typically used when welding particular types of sheet metal by application of heat.

spot weld

 

 

 

 

 

 

 

 

Stud Weld – is a form of spot welding where a bolt or specially formed nut is welded on to another metal part. The bolts may be automatically fed into the spot welder. Weld nuts generally have a flange with small nubs that melt to form the weld. Studs have a necked down, unthreaded area for the same purpose.

stud weld

 

 

Weld Terminology

  • Leg
  • Face
  • Throat
  • Groove radius
  • Root opening (groove weld) is the space between the pieces before welding
  • Root face
  • Groove angle

weld term

 

 

 

 

 

 

weld term

 

 

 

 

 

weld term

 

 

 

 

 

 

 

 

 

 

weld symbols

 

Significance of Arrow

significance of arrow

 

 

 

 

 

 

 

 

Weld Symbols

Fillet Weld Symbol

fillet symbol

 

 

 

 

 

 

Square Groove Weld Symbol

square groove symbol

 

 

 

 

 

 

Bevel Groove Weld Symbol

bevel groove symbol

 

 

 

 

 

 

 

 

 

 

V-Groove Weld Symbol

v groove symbol

 

 

 

 

 

 

 

 

 

 

J-Groove Weld Symbol

j groove symbol

 

 

 

 

 

 

U-Groove Weld Symbol

u groove symbol

 

 

 

 

 

 

 

Flare-Bevel Groove Weld Symbol

flare bevel groove weld symbol

 

 

 

 

 

 

 

 

 

 

Flare-V Groove Weld Symbol

Flare-V Groove Weld Symbol

 

 

 

 

 

 

 

Plug or Slot Weld Symbol

Plug or Slot Weld Symbol

 

 

 

 

 

 

Stud Weld Symbol

Stud Weld Symbol

 

 

 

 

 

 

Spot Weld Symbol

Spot Weld Symbol

 

 

 

 

 

 

Basic and Supplementary Weld Symbols

Basic and Supplementary Weld Symbols

 

 

Basic and Supplementary Weld Symbols

 

 

Back or Backing Weld

Back or backing weld symbols are used to indicate bead-type back or backing welds deposited at the back of single-groove welds to assure complete root penetration.

The back weld is made after the groove weld.

The backing weld is made before the groove weld.

Back or Backing Weld

 

 

 

 

 

 

 

 

 

 

 

Surfacing

Surfacing is the deposition of filler metal on a metal surface to obtain desired properties or dimensions.

 

Field Weld

Field welds are welds not made in the shop or at the place of initial construction.

Small black flag symbol is placed above and at right angles to the reference line.

 

All Around Weld

Welds extending completely around a joint is indicated by a weld-all-around symbol placed at the intersection of the reference line and the arrow.

It is not required for welds extending around the circumference of a pipe.

 

Finish Contour

Finish Contour

 

 

 

 

 

 

 

Additional Information

  • Welding symbols can be combined

Additional Information

 

 

 

  • Multiple reference lines can be used to indicate sequencing

–  Line closest to the arrow is first

Additional Information

 

 

 

 

 

  • Cranked arrow line points to the member to be prepared

Additional Information

 

 

 

 

  • Application of Break in Arrow Symbol

Application of Break in Arrow SymbolApplication of Break in Arrow Symbol

Application of Break in Arrow Symbol

 

 

 

Photo credit to bugphai of freedigitalphotos.net

 

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