LGHG2 Grade Cold-Rolled Steel Strip for Welded Pipes

LGHG2 is a mid-grade cold-rolled steel strip for welded pipe substrates produced by Lianyuan Steel, with its strength, formability and weldability falling between LGHG1 and LGHG3. It is more suitable for high-frequency welded/laser welded precision pipes requiring medium precision, thin walls, relatively high pressure or complex forming, and is widely used in home appliances, automotive, hydraulic & pneumatic, construction machinery and other industries.

Typical Application Scenarios (Industry × Component × Working Condition)

Grade Differences & Selection Recommendations

Grade Ranking: LGHG1 ＜ LGHG2 ＜ LGHG3 (increasing strength, formability and weldability)

Selection Principles

LGHG1: For general-precision, low-pressure, simple-forming welded pipes

LGHG2: For medium-precision, medium-pressure welded pipes with complex forming or higher welding requirements

LGHG3: For high-precision, high-pressure, thin-walled welded pipes with complex forming or severe working conditions

Key Parameters: Determine the grade based on the pipe’s outer diameter, wall thickness, working pressure, medium (e.g., refrigerant/fuel) and welding process (high-frequency welding/laser welding). Request Lianyuan Steel to provide the chemical composition, mechanical properties and surface grade of each batch.

Processing & Welding Key Points

Thickness & Width: Common thickness range is 0.3–2.0 mm. The width is determined by the pipe circumference plus forming allowance. Lianyuan Steel can perform slitting and flattening according to orders, controlling edge burrs and camber to improve welding stability and pipe ovality.

Welding Process: High-frequency induction welding or laser welding is preferred, featuring high weld strength and stable flaw detection pass rate. Post-welding processes such as straightening, deburring, pickling/passivation and galvanization are usually required to further improve dimensional stability and corrosion resistance.

Surface Treatment: Pickling/passivation, galvanization or electrophoretic coating can be selected according to working conditions to enhance corrosion resistance and appearance quality.

Procurement & Acceptance Process

Clarify Requirements: Confirm the pipe’s outer diameter, wall thickness, length, working pressure, medium and working environment, then reverse-engineer the substrate’s LGHG2 grade, thickness, width, surface requirements and slitting/flattening dimensions.

Coordinate with Lianyuan Steel & Pipe Manufacturers: Purchase LGHG2 substrates from Lianyuan Steel, and select a pipe manufacturer equipped with high-frequency/laser welding and finishing capabilities. Sign an integrated supply contract for substrates and processing to ensure quality and delivery schedule.

Quality Acceptance: Require quality certificates for substrates (including chemical composition, mechanical properties, surface grade and dimensional tolerance). Conduct ultrasonic flaw detection, hydrostatic/air tightness tests, dimensional re-inspection and surface inspection on finished pipes before delivery. Salt spray tests or fatigue tests can be added if necessary.

Common Misunderstandings & Precautions

Confusing Substrates with Finished Pipes: Lianyuan Steel mainly supplies LGHG series substrates; finished welded pipes are processed by downstream manufacturers. Avoid directly inquiring about finished pipes from Lianyuan Steel to prevent procurement delays.

Grade Mismatch: LGHG2 is suitable for medium-high pressure and complex forming scenarios. For non-such applications, LGHG1 can be selected to reduce costs; for high-pressure or severe working conditions, upgrade to LGHG3 or special alloy pipes. 

Ignoring Quality Certificates: LGHG is an enterprise-grade designation without a unified national standard equivalent. Must require Lianyuan Steel to provide quality certificates for each batch, which should be consistent with the order technical agreement.