PENGARUH NARROW GAP WELDING TERHADAP STRUKTUR MAKRO DAN KEKERASAN HEAT AFFECTED ZONE

Prayogi, Mochamad Izuddin (2026) PENGARUH NARROW GAP WELDING TERHADAP STRUKTUR MAKRO DAN KEKERASAN HEAT AFFECTED ZONE. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Penggunaan miter bend pada sistem perpipaan sering dilakukan untuk mengatasi ketidaksesuaian posisi pipa di lapangan, namun keterbatasan ruang terkadang menyebabkan jarak antar sambungan las (dimensi M) lebih kecil dari standar sehingga berpotensi menimbulkan tumpang tindih Heat Affected Zone (HAZ). Penelitian ini bertujuan untuk mengetahui pengaruh variasi dimensi M terhadap sifat mekanis dan karakteristik sambungan las pada miter bend menggunakan metode Shielded Metal Arc Welding (SMAW). Variasi dimensi M yang digunakan yaitu 25 mm, 35 mm, dan 45 mm, kemudian dilakukan pengujian tarik, bending, serta pengamatan struktur makro. Hasil penelitian menunjukkan bahwa peningkatan dimensi M memberikan pengaruh positif terhadap kualitas sambungan las, ditunjukkan dengan meningkatnya nilai yield strength dari 274,81 MPa menjadi 357,19 MPa dan nilai ultimate tensile strength dari 378,53 MPa menjadi 466,91 MPa. Selain itu, hasil pengujian bending menunjukkan kecenderungan penurunan cacat terbuka seiring bertambahnya dimensi M. Berdasarkan evaluasi ASME BPVC Section IX, variasi 35 mm dan 45 mm memenuhi kriteria keberterimaan, sedangkan variasi 25 mm tidak memenuhi batas minimum kekuatan tarik yang dipersyaratkan. Hasil penelitian ini menunjukkan bahwa semakin besar jarak antar sambungan las maka pengaruh overlapping HAZ semakin kecil sehingga sifat mekanis sambungan las menjadi lebih baik.
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The use of miter bends in piping systems is commonly implemented to address pipeline misalignment in the field. However, spatial constraints sometimes result in the distance between weld joints (dimension M) being smaller than the standard, which potentially causes overlapping Heat Affected Zones (HAZ). This study aims to determine the effect of variations in dimension M on the mechanical properties and characteristics of weld joints in miter bends using the Shielded Metal Arc Welding (SMAW) method. The variations of dimension M evaluated were 25 mm, 35 mm, and 45 mm, followed by tensile testing, bending testing, and macrostructural observation. The results showed that increasing dimension M had a positive effect on the quality of the weld joint, as indicated by an increase in yield strength from 274.81 MPa to 357.19 MPa and ultimate tensile strength from 378.53 MPa to 466.91 MPa. Furthermore, the bending test results demonstrated a downward trend in open defects as dimension M increased. Based on the ASME BPVC Section IX evaluation, the 35 mm and 45 mm variations met the acceptance criteria, whereas the 25 mm variation failed to meet the required minimum tensile strength limit. This study indicates that a larger distance between weld joints minimizes the effect of overlapping HAZ, thereby enhancing the mechanical properties of the weld joint.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Heat Affected Zone, jarak sambungan las, miter bend, sifat mekanis, struktur makro. ======================================================================================================================== Heat Affected Zone, mechanical properties, microstructure, miter bend, weld spacing.
Subjects:	T Technology > TJ Mechanical engineering and machinery T Technology > TN Mining engineering. Metallurgy T Technology > TS Manufactures
Divisions:	Faculty of Marine Technology (MARTECH) > Marine Engineering > 36202-(S1) Undergraduate Thesis
Depositing User:	Mochamad Izzuddin Prayogi
Date Deposited:	06 Aug 2026 00:59
Last Modified:	06 Aug 2026 00:59
URI:	http://repository.its.ac.id/id/eprint/143344

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