Preheat API 5L Gr.B untuk SMAW (non-low-hydrogen) — up to 3/4"
Suhu pemanasan awal dan antar lajur minimum untuk API 5L Gr.B dilas dengan SMAW (non-low-hydrogen) pada ketebalan up to 3/4", sesuai AWS D1.1:2025 Tabel 5.11.
Berdasarkan AWS D1.1:2025 Tabel 5.11 — setiap nilai dilacak ke pasal.
Proses SMAW bukan hidrogen rendah
SMAW (Non-Low-Hydrogen)
Non-low-hydrogen SMAW (E6010/E6011) uses cellulosic electrodes with higher hydrogen potential, assigned to Category A in Table 5.11.
On pipe joints, non-low-hydrogen SMAW root passes with E6010 use the keyhole technique to ensure complete penetration. Pipe rotation (roll welding) is preferred when practical; fixed-position welding requires 5G or 6G qualified procedures. The cellulosic coating generates significant spatter, so adjacent base metal should be protected with anti-spatter compound.
API 5L Gr.B
API 5L Grade B is the baseline pipeline steel specification used for oil, gas, and water transmission lines, with 35 ksi minimum yield and 60 ksi minimum tensile (PSL 1). At PSL 2, tighter chemistry controls (0.22% max carbon, 1.20% max manganese, 0.43% max CE-IIW) improve weldability and toughness consistency. Grade B pipeline joints welded under D1.1 follow Category A (non-low-hydrogen) and Category B (low-hydrogen) preheat requirements. API 5L covers both seamless and welded (HFW, SAW, COWB) pipe in sizes from 1/2" through 80" outside diameter. The pipeline industry typically qualifies procedures under API 1104 rather than D1.1, but structural attachments to pipeline components often fall under D1.1 jurisdiction.
Mengapa Preheat Ini untuk API 5L Gr.B dengan SMAW
Baseline pipeline steel for oil and gas transmission at 35 ksi yield. At this thickness, SMAW with non-low-hydrogen electrodes places the joint in Category A of Table 5.11. The minimum preheat of 32°F compensates for the higher diffusible hydrogen from cellulosic electrode coatings. The thicker the material, the longer hydrogen takes to escape the heat-affected zone, which is why preheat rises with thickness even for this common grade.
Aplikasi Umum untuk API 5L Gr.B
Specified for water transmission mains, natural gas distribution laterals, irrigation pipelines, fire hydrant supply loops, sewer force mains, and gathering system tie-ins. API 5L Gr.B pipeline girth welds use root passes with E6010 cellulosic electrodes followed by fill passes with E7018 or GMAW. Bell-hole repair joints and split-tee hot taps are typical field weld configurations. Pipeline wall thicknesses for municipal water service typically range from 0.250" to 0.500" depending on diameter and operating pressure. Mainline girth welds are radiographically inspected at 100% on high-consequence area crossings and river/road bores. Pipe diameters in municipal water range from 6" to 48" NPS, with 12" to 24" being the most common for trunk mains. Field welders typically qualify on 6G fixed pipe to demonstrate proficiency in all positions encountered during mainline tie-in and repair operations.
Mengapa Preheat Penting pada up to 3/4"
Thin material sheds heat quickly, allowing hydrogen to escape the HAZ readily — lowest preheat tier in Table 5.11.
Mengapa 32°F untuk API 5L Gr.B?
Preheat minimum 32°F (0°C) berarti tidak diperlukan pemanasan awal aktif di atas kondisi beku. Tabel 5.11 Kategori A pada ketebalan ini menetapkan minimum ambien karena API 5L Gr.B dengan SMAW bukan hidrogen rendah memiliki keuletan cukup dan karbon ekuivalen rendah sehingga risiko retak hidrogen minimal. Sesuai catatan kaki (a), jika bekerja di bawah 32°F, panaskan awal sambungan hingga setidaknya 70°F (20°C) dan pertahankan selama pengelasan.
Baja Lain dengan SMAW (non-low-hydrogen) pada up to 3/4"
API 5L Gr.B dengan SMAW (non-low-hydrogen)
Coba Kombinasi Berbeda
Gunakan kalkulator preheat interaktif untuk mencari kombinasi baja, proses, dan ketebalan dari D1.1:2025 Tabel 5.11.
Panduan Pengelasan API 5L Gr.B
Data referensi D1.1:2025. Tidak berafiliasi dengan AWS.