API 5L Gr.B SMAW (non-low-hydrogen) 예열 — up to 3/4"

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.

SMAW를 사용한 API 5L Gr.B의 이 예열 이유

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.

API 5L Gr.B의 일반적인 용도

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.

up to 3/4"에서 예열이 중요한 이유

Thin material sheds heat quickly, allowing hydrogen to escape the HAZ readily — lowest preheat tier in Table 5.11.

up to 3/4"에서 SMAW (non-low-hydrogen)를 사용하는 다른 강재

API 5L Gr.B, SMAW (non-low-hydrogen)

다양한 조합 시도

인터랙티브 예열 계산기를 사용하여 D1.1:2025 표 5.11의 모든 강재, 공정, 두께 조합을 조회하세요.

API 5L Gr.B 용접 가이드