DESAIN LAS (Welding Design)

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DESAIN LAS

(

Welding Design

)

Departemen Metalurgi & Material

Fakultas Teknik Universitas Indonesia

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Sambungan Las (Weld Joint)

 Sambungan las merupakan penerima logam pengisi yang didepositkan.

 Sambungan las dipilih berdasarkan

 lokasi,

 persiapan yang diperlukan,  peralatan pengelasan yang

digunakan, dan

 aplikasi sambungan las.

 Sambungan las dasar terdiri dari

 butt (tumpul),  lap (tumpang),  T,

 edge (sisi) dan  corner (sudut)

Sambungan Tumpul ( butt joint )

 dibentuk bila dua anggota sambungan

yang berada kurang lebih dalam bidang yang sama didekatkan antara ujung satu sama lainnya.

 dapat digunakan dengan atau tanpa

persiapan terhadap anggota sambungan yang memiliki ketebalan yang sama ataupun berbeda.

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Butt Joint

Butt joint- a joint

between two

members aligned

approximately in

the same plane

Different Edge Shapes and

Symbols for some Butt-Joints

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Application for some Butt-Joints

Sambungan Sudut (corner joint)

 Merupakan sambungan las yang dibentuk

bila dua anggota sambungan diposisikan membentuk sudut kurang lebih 90

dengan sambungan las pada bagian luar anggota sambungan.

 Umumnya digunakan pada konstruksi

bejana tekan dan tangki. Logam pengisi dapat dibutuhkan dan dapat pula tidak tergantung pada desain dan fungsi

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Corner Joint

Corner joint - a joint

between two members

located at right angles

to each other

Some Different Edge Shapes

and Symbols for Corner Joints

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Sambungan T ( T-joint )

bila dua anggota sambungan diposisikan kurang lebih 90 satu sama lain dalam bentuk T.

 Jika dimungkinkan, dilas pada kedua

sisinya untuk mendapatkan kekuatan maksimum.

 umumnya digunakan dalam fabrikasi

struktur penopang dimana beban

ditransfer ke bidang yang berbeda pada kurang lebih 90.

T-Joint

T- joint - a joint between

two members located

approximately at right

angles to each other in

the form of a T

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Some Different Edge Shapes

and Symbols for T-Joint

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Sambungan Tumpang (lap joint)

bila dua anggota sambungan diposisikan saling menumpuk satu sama lain.

 Lebih kuat dibandingkan dengan

sambungan tumpul, tetapi

mengakibatkan terjadinya penambahan berat.

 umumnya dilas pada kedua sisinya  umumnya digunakan selama proses

perbaikan dan untuk menambah panjang material standar ke panjang yang

diperlukan

Lap Joint

Lap Joint- a joint

between two

overlapping

members

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Some Different Edge Shapes

and Symbols for Lap Joints

Sambungan Sisi (edge joint)



merupakan sambungan las yang

dibentuk bila sisi dua anggota

sambungan akan disambung.



sisi yang dilas sejajar satu sama

lain.



sering dipakai dalam menyambung

struktur penopang dan struktur baja

yang pendek.

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Edge Joint

Edge joint- a joint

between the edges of

two or more parallel

or nearly parallel

members

Some Different Edge Shapes

and Symbols for Edge Joints

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Proper terminology is needed in

everyday job communication



Joint design

identifies, “the shape ,

dimensions, and configuration of

the joint



The individual workpieces of a joint

are called

members

.



Three types members :

nonbutting

member

,

butting member

, and

splice member

A non-butting member is “a joint member that is free to move in any direction perpendicular to its thickness dimension

A butting member is “a joint member that is prevented, by the other member from movement in one direction

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A splice member is “ the work piece that

spans the joint in a spliced joint

Single-spliced butt joint

Double-spliced

butt joint with

joint filler

Types of Welds

 Numerous welds can be applied to the various

types of joints

 Considerations when choosing joint geometry

and weld types:



accessibility to the joint for welding



type of welding process being used



suitability to the structural design

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Jenis Lasan

(

Types of Weld)

groove, fillet, plug, slot, stud, spot, projection, seam,

back atau backing weld, surfacing dan

flange.

Types of Welds

Groove Welds

 A groove weld is “ a weld made in a groove

between the work pieces”

 There are eight types of groove welds

 Square-groove  Scarf  V-groove  Bevel-groove  U-groove  J-groove  Flare-v-groove  Flare-bevel-groove

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Groove Welds

Square and double square-groove welds

 Square-groove welds are the most economical

to use, but are limited by thickness of the members

 Welds for one side are normally limited to a

1/4 inch or less

Groove Welds

V-and double V-groove welds

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Groove Welds

Bevel- and double-bevel-groove welds

 Bevel- and J- groove welds are more difficult to weld than V- or U-groove welds

 Bevel welds are easier in horizontal

Types of Welds

U-groove and Double U-groove



Welds in using J- and U-grooves can be

used to minimize weld metal



These welds are very useful in thicker

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Groove Welds

J-and double-J-groove welds

 J-groove are more

difficult to weld because of the one vertical side (except in horizontal)

 J-and U- are used

when economic factors outweigh the cost of edge

preparation

Groove Welds

flare-bevel and flare-v-groove welds

 Flare -bevel and

flare-v-groove welds are used in

connection with flanged or rounded member

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Groove Welds

Scarf

 Scarf is used for

brazing

Groove Welds



Their names imply what the actual

configurations look like when viewed in a

cross section



Single groove welds are welded from

only one side



Double groove welds are welded on both

sides



Groove welds in many combinations are

used selection is influenced by

accessibility, economy, adaptation to

structural design

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Groove Welds

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Ir. Winarto, M.Sc. PhD

Welding Symbols

Understanding Welding Symbols

Terms and Definitions

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Reference Line (Required element)

Arrow

Tail

Reference Line must always be horizontal,

Arrow points to the line or lines on drawing which clearly identify the proposed joint or weld area.

The tail of the welding symbol is used to indicate the welding or cutting processes, as well as the welding specification, procedures, or the supplementary information to be used in making the weld.

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Reference Line (Required element)

Arrow

Tail

Reference Line must always be horizontal,

Arrow points to the line or lines on drawing which clearly identify the proposed joint or weld area.

The tail of the welding symbol is used to indicate the welding or cutting processes, as well as the welding specification, procedures, or the supplementary information to be used in making the weld.

Basic components of a WELDING SYMBOL

Tail omitted when reference not used

Arrow connects reference line to arrow side member of joint or arrow side of joint

A circle at the tangent of the arrow and the reference line means welding to be all around.

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A flag at the tangent of the reference line and arrow means Field Weld.

Field Weld Symbol

ARROW SIDE

OTHER SIDE

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Break in arrow means arrow side must be side

that beveling or other preparation required.

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Fillet Weld (Other Side)

1/4 1/4

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1/4 1/4 (5/16) (5/16) Depth of preparation or groove Depth of penetration

Example of Double Bevel Groove weld

Plug or Slot Weld Symbol

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5/16

What does this symbol Represent?

Single-Bevel-Groove and Double

Fillet weld Symbols

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Ir. Winarto, M.Sc. PhD

Chain Intermittent Fillet Weld

Weld both sides each end and 10

inches center to center in between

1/4 1/4

2-10 2-10

10 in

Staggered Intermittent Fillet Weld

Weld ends than 10 inch centers

staggered each side

10 in 2-10

2-10 1/4

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Tabel 1.1 Daftar metode pengujian tak merusak berikut singkatannya

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KEKUATAN SAMBUNGAN LASAN

Dalam mendesain suatu struktur yang difabrikasi dengan pengelasan, berbagai jenis kukuatan sambungan las harus menjadi pertimbangan, seperti kuat tarik, energi terserap (impact), kuat fatik dan lain-lain tergantung pada spesifikasi yang diberikan atau dipersyaratkan.

Formula yang dapat digunakan untuk menentukan kekuatan sambungan untuk lasan dengan alur dan las sudut adalah:

dimana:

P = beban yang diberikan

Ss/c= tegangan tarik atau tekan pada penampang leher (throat) Ss= tegangan geser pada penampang leher