LSAW Straight Seam Steel Pipe Supplier | API 5L Gr.B ERW & LSAW Pipe

Description

LSAW and ERW Straight Seam Steel Pipe – API 5L Gr.B for Oil, Gas & Water Infrastructure

Straight seam welded steel pipe is manufactured by forming flat steel strip or plate into a cylindrical shape and welding the longitudinal edges to create a single, straight weld seam. This category includes two distinct processes: Electric Resistance Welded (ERW) for small-to-medium diameters and Longitudinal Submerged Arc Welded (LSAW) for large diameters. Both are classified as straight seam pipes under ISO 3183 and API 5L, and are fundamentally different from spiral-welded (SSAW/HSAW) pipe, which features a helical seam.

ERW pipe is produced from hot-rolled coil using high-frequency resistance welding, offering high dimensional consistency and cost efficiency for standard line pipe applications. LSAW pipe is fabricated from discrete steel plates using submerged arc welding, enabling thicker walls, larger diameters, and full non-destructive testing of the entire weld seam—making it suitable for critical, high-pressure, or sour service environments.

Process-Specific Capabilities and Standard Compliance (2026)

Note: Per API 5L-24 Clause 5.2, both ERW and LSAW are classified as welded line pipe with longitudinal seam. Spiral-welded pipe (SSAW) is excluded from this category.

Quality Assurance and Certification

All straight seam pipes are supplied with:

• Full chemical analysis (C, Mn, S, P, Si) per heat number

• Tensile test results (YS, UTS, elongation)

• Hydrostatic test at specified pressure (e.g., 25 MPa for API 5L X65)

• EN 10204 3.1 Mill Test Report

• Optional: HIC/SOC testing (NACE TM0284), impact testing (ISO 148-1)

PSL2 orders include additional requirements: hardness survey (≤250 HV10), weld macro/micro examination, and full traceability from plate to finished pipe.

Critical Limitations and Engineering Guidance

• ❌ Not suitable for high-temperature service above 400°C — welded microstructure lacks creep strength; seamless pipe (ASTM A106/A335) required.

• ❌ ERW pipe with OD > 24" is not commercially viable — plate-based LSAW is the only feasible process for large diameters.

• ❌ Do not use uncoated LSAW/ERW pipe in buried service without cathodic protection — risk of external corrosion in moist soils.

• ✅ LSAW is preferred for seismic zones, directional drilling, and deepwater applications due to superior weld integrity and fracture toughness.

Typical Project Applications

• ERW: City gas networks (Gr.B, OD 114mm), industrial firewater loops (ASTM A53), irrigation mains

• LSAW: Transnational oil pipelines (X70, OD 1016mm), potable water transmission (P265GH with FBE+concrete weight coat), offshore platform conductors

As an ISO 9001-certified manufacturer with dedicated ERW and LSAW production lines, CNAS-accredited lab, and annual capacity exceeding 300,000 metric tons, Shenlong delivers straight seam steel pipe with full compliance to API 5L-24, ASTM A53-24, and EN 10217-2:2023. Custom beveling (compound J-prep), threading, and coating (3PE, FBE, galvanizing) available. Third-party inspection (SGS, BV, LR) supported globally.

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Content reviewed by Pipeline Materials Engineering Team – February 2026

Straight seam steel pipe is a steel pipe with the weld seam parallel to the longitudinal direction of the steel pipe. Usually divided into metric electric welded steel pipe, electric welded thin-walled pipe, transformer cooling oil pipe and so on. The production process of straight seam welded pipe is simple, the production efficiency is high, the cost is low, and the development is fast. The strength of the spiral welded pipe is generally higher than that of the straight seam welded pipe. However, compared with the same length of straight seam pipe, the length of the weld is increased by 30~100%, and the production speed is lower.

According to the production process, straight seam steel pipes can be divided into high frequency straight seam steel pipes and submerged arc welded straight seam steel pipes. Submerged arc welded straight seam steel pipes are divided into UOE, RBE, JCOE steel pipes according to their different forming methods.

The main processing methods of straight seam steel pipe are:

Forged steel: A press working method that uses the reciprocating impact force of a forging hammer or the pressure of a press to change the billet into the shape and size we need.

Extrusion: It is a processing method in which the steel is placed in a closed extrusion tube, and pressure is applied at one end to extrude the metal from the specified die hole to obtain a finished product with the same shape and size. It is mostly used for the production of non-ferrous metal materials. .

Rolling: A pressure processing method in which a steel metal billet is passed through a gap (various shapes) of a pair of rotating rolls, and the cross-section of the material is reduced and the length is increased due to the compression of the rolls.

Drawing steel: It is a processing method that draws a rolled metal billet (shape, pipe, product, etc.) through a die hole to reduce the cross-section and increase the length.

For cold working.

Straight seam steel pipes are mainly used in tap water engineering, petrochemical industry, chemical industry, electric power industry, agricultural irrigation, and urban construction.

For liquid transportation: water supply, drainage.

For gas transportation: gas, steam, liquefied petroleum gas.

For structure: for piling pipe, for bridge; for wharf, road, building structure, etc.

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