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DESAIN LAS(Welding Design)
Departemen Metalurgi & Material
Fakultas Teknik Universitas Indonesia
Konsep Desain & Fabrikasi Las
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Sambungan Las (Weld Joint)
Sambungan las merupakanpenerima logam pengisi yangdidepositkan.
Sambungan las dipilihberdasarkan 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 sambunganyang berada kurang lebih dalam bidangyang sama didekatkan antara ujung satusama lainnya.
dapat digunakan dengan atau tanpapersiapan terhadap anggota sambunganyang memiliki ketebalan yang samaataupun berbeda.
umumnya digunakan pada subassemblies,selama fabrikasi dan proses perbaikan.
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Butt Joint
Butt joint- a jointbetween twomembers alignedapproximately inthe same plane
Different Edge Shapes andSymbols for some Butt-Joints
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Application for some Butt-Joints
Sambungan Sudut (corner joint)
Merupakan sambungan las yang dibentukbila dua anggota sambungan diposisikanmembentuk sudut kurang lebih 90
dengan sambungan las pada bagian luaranggota sambungan.
Umumnya digunakan pada konstruksibejana tekan dan tangki. Logam pengisidapat dibutuhkan dan dapat pula tidaktergantung pada desain dan fungsisambungan.
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Corner Joint
Corner joint - a jointbetween two memberslocated at right anglesto each other
Some Different Edge Shapesand Symbols for Corner Joints
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Sambungan T ( T-joint )
Merupakan sambungan las yang dibentukbila dua anggota sambungan diposisikankurang lebih 90 satu sama lain dalam
bentuk T.
Jika dimungkinkan, dilas pada keduasisinya untuk mendapatkan kekuatanmaksimum.
umumnya digunakan dalam fabrikasistruktur penopang dimana bebanditransfer ke bidang yang berbeda padakurang lebih 90.
T-Joint
T- joint - a joint betweentwo members locatedapproximately at rightangles to each other inthe form of a T
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Some Different Edge Shapesand Symbols for T-Joint
Application for T-Joint
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Sambungan Tumpang (lap joint)
Merupakan sambungan las yang dibentukbila dua anggota sambungan diposisikansaling menumpuk satu sama lain.
Lebih kuat dibandingkan dengansambungan tumpul, tetapimengakibatkan terjadinya penambahanberat.
umumnya dilas pada kedua sisinya
umumnya digunakan selama prosesperbaikan dan untuk menambah panjangmaterial standar ke panjang yangdiperlukan
Lap Joint
Lap Joint- a jointbetween twooverlappingmembers
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Some Different Edge Shapesand Symbols for Lap Joints
Sambungan Sisi (edge joint)
merupakan sambungan las yangdibentuk bila sisi dua anggotasambungan akan disambung.
sisi yang dilas sejajar satu samalain.
sering dipakai dalam menyambungstruktur penopang dan struktur bajayang pendek.
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Edge Joint
Edge joint- a jointbetween the edges oftwo or more parallelor nearly parallelmembers
Some Different Edge Shapesand Symbols for Edge Joints
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Proper terminology is needed ineveryday job communication
Joint design identifies, “the shape ,dimensions, and configuration ofthe joint
The individual workpieces of a jointare called members .
Three types members : nonbuttingmember, butting member , andsplice member
A non-butting member is “a joint member that is free to movein any direction perpendicular to its thickness dimension
A butting member is “a joint member that is prevented, bythe other member from movement in one direction
perpendicular to its thickness dimension”
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A splice member is “ the work piece thatspans the joint in a spliced joint
Single-splicedbutt joint
Double-splicedbutt joint with
joint filler
Types of Welds
Numerous welds can be applied to the varioustypes of joints
Considerations when choosing joint geometryand weld types:
accessibility to the joint for welding
type of welding process being used
suitability to the structural design
cost of welding
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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 WeldsGroove Welds
A groove weld is “ a weld made in a groovebetween 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 WeldsSquare and double square-groove welds
Square-groove welds are the most economicalto use, but are limited by thickness of themembers
Welds for one side are normally limited to a1/4 inch or less
Groove WeldsV-and double V-groove welds
With thicker materials joint accessibility must beprovided for welding to ensure weld soundnessand strength
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Groove WeldsBevel- and double-bevel-groove welds
Bevel- and J- groove welds are more difficult to weldthan V- or U-groove welds
Bevel welds are easier in horizontal
Types of WeldsU-groove and Double U-groove
Welds in using J- and U-grooves can beused to minimize weld metal
These welds are very useful in thickersections
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Groove WeldsJ-and double-J-groove welds
J-groove are moredifficult to weldbecause of the onevertical side (exceptin horizontal)
J-and U- are usedwhen economicfactors outweigh thecost of edgepreparation
Groove Weldsflare-bevel and flare-v-groove welds
Flare -bevel andflare-v-groove weldsare used inconnection withflanged or roundedmember
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Groove WeldsScarf
Scarf is used forbrazing
Groove Welds
Their names imply what the actualconfigurations look like when viewed in across section
Single groove welds are welded fromonly one side
Double groove welds are welded on bothsides
Groove welds in many combinations areused selection is influenced byaccessibility, economy, adaptation tostructural design
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Groove Welds
Fillet 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 orweld 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 informationto 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 orweld 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 informationto be used in making the weld.
Basic components of a WELDING SYMBOL
Tail omitted when reference not used
Arrow connects reference line to arrow sidemember of joint or arrow side of joint
A circle at the tangent of the arrow and the reference linemeans welding to be all around.
All the way Around
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A flag at the tangent of the reference line andarrow means Field Weld.
Field Weld Symbol
ARROW SIDE
OTHER SIDE
Weld Symbol Terminology
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Break in arrow means arrow side must be sidethat beveling or other preparation required.
Fillet Weld (Arrow Side Only)
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Fillet Weld (Other Side)
1/4
1/4
Size of Fillet Weld Noted
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1/4
1/4
(5/16)
(5/16)
Depth of preparation orgroove
Depth of penetration
Example of Double Bevel Groove weld
Ir. Winarto, M.Sc. PhD
Plug or Slot Weld Symbol
Arrow Side
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5/16
5/16
What does this symbol Represent?
Single-Bevel-Groove and DoubleFillet weld Symbols
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Ir. Winarto, M.Sc. PhD
Chain Intermittent Fillet WeldWeld both sides each end and 10inches center to center in between
1/4
1/4
2-10
2-10
10 in
Ir. Winarto, M.Sc. PhD
Staggered Intermittent Fillet WeldWeld ends than 10 inch centersstaggered each side
10 in
10 in
2-10
2-101/4
1/4
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Tabel 1.1 Daftar metode pengujian takmerusak berikut singkatannya
Tabel 1.1 Daftar metode pengujian takmerusak 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-laintergantung pada spesifikasi yang diberikan atau dipersyaratkan.
Formula yang dapat digunakan untuk menentukan kekuatan sambunganuntuk lasan dengan alur dan las sudut adalah:
dimana:P = beban yang diberikanSs/c = tegangan tarik atau tekan pada penampang leher (throat)Ss = tegangan geser pada penampang lehera = tebal leherl = panjang logam las efektif a l = luas penampang leher.
la
PS
la
PS s
cs
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KEKUATANSAMBUNGAN LASAN
Tebal leher diten-ukandengan formula:
SS
a 707,02
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T Fillet Welds
Weld subject to longitudinal shear only
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Latihan Soal Kekeuatan Las
Hitunglah ukuran minimum fillet(fillet weld size) suatu konstruksilas seperti gambar di sebelah, jika
diketahui kekuatan geser ( ) yang
sejajar pembebanan besarnya 20MPa atau N/mm2, sedangkan beban(P) yang ditanggung oleh konstruksitsb adalah 20000 N (2 Ton) denganpanjang las setiap sisi (W) sebesar100 mm.
