Seamless Steel Tube & Pipe (SMLS)
Seamless steel tube and pipe (SMLS) is a tubular product manufactured from a solid billet through piercing and elongation processes, resulting in a continuous perimeter without any welded seam.
Material
Carbon Steel, Alloy Steel, Stainless Steel. Common grades include ASTM A106 Gr. B, API 5L PSL1/PSL2 (Gr. B, X42-X80), ASTM A333 Gr. 6 (low-temp), ASTM A335 P11/P22/P91 (chrome-moly), ASTM A312 TP304/316.
Model
SMLS Pipe, Seamless Tube
Size
Outer Diameter (OD) range: approximately 6 mm to 850+ mm. Common nominal pipe sizes (NPS) from 1/8″ to 36″.
Thickness
Wall thickness defined by schedule (e.g., SCH 40, 80, XXS) or directly in mm, ranging from less than 1 mm to over 100 mm.
Standard
ASTM A106/A53 (CS), ASTM A333 (Low-Temp), ASTM A335 (Alloy), API 5L (Line Pipe), EN 10216 (P195-P460), JIS G3454/G3456.
MOQ
5 Metric Tons (subject to size and grade).
Delivery Time
Standard lead time is 6 to 12 weeks, depending on grade, size, heat treatment, and quantity.
Long Description
Seamless steel tube and pipe, abbreviated as SMLS, is produced by heating a solid cylindrical steel billet and then piercing it with a mandrel to create a hollow shell. This shell is subsequently elongated and rolled to achieve the desired diameter and wall thickness through processes such as hot rolling, extrusion, or cold drawing. The absence of a longitudinal weld seam eliminates a potential point of failure, providing superior structural integrity, uniformity in wall thickness, and enhanced performance under high pressure, high temperature, or corrosive environments. This product category is essential for critical applications where reliability is paramount. It is manufactured to precise dimensional tolerances and a wide range of steel grades, covering carbon steel, alloy steel, and stainless steel for various industrial sectors.
Key Product Highlights
The seamless manufacturing process ensures homogeneous microstructure and consistent mechanical properties throughout the pipe circumference.
SMLS pipe offers higher pressure ratings and better reliability for critical services compared to welded alternatives.
It is available in a broad spectrum of diameters, wall thicknesses (schedules), and material grades to meet exact project specifications.
The product exhibits excellent internal surface finish and dimensional accuracy, beneficial for fluid flow and precision mechanical applications.
Suitable for severe service conditions including high pressure, high/low temperature, and corrosive media.
Product Advantages
The lack of a weld seam eliminates the need for weld seam inspection and provides inherent leak integrity.
Superior metallurgical homogeneity enhances resistance to corrosion, erosion, and fatigue.
Comprehensive certification packages, including hydrostatic test reports and full traceability, support quality assurance for critical projects.
Can be supplied with various end finishes (plain, beveled, threaded) and heat treatments as required.
Established global supply chain for both standard and specialty grades ensures availability for maintenance and turnkey projects.
Industry Application
This product is used for high-pressure steam lines in power plants, process piping in refineries and chemical plants, oil and gas transmission lines, downhole tubing, heat exchanger tubes, hydraulic cylinders, bearing races, and structural applications.
Technical Specifications
| Parameter | Unit | Carbon Steel Pipe (e.g., A106 Gr.B) | Alloy Steel Pipe (e.g., A335 P11) | Low-Temp Pipe (e.g., A333 Gr.6) | Notes |
|---|---|---|---|---|---|
| Carbon Content (C) | % | ≤ 0.30 | 0.05 – 0.15 | ≤ 0.30 | Varies significantly by grade; alloy grades have specific ranges. |
| Manganese (Mn) | % | 0.29 – 1.06 | 0.30 – 0.60 | ≥ 0.29 | An important element for strength and hardenability. |
| Phosphorus (P) | % | ≤ 0.035 | ≤ 0.025 | ≤ 0.025 | Tighter controls in alloy and low-temp grades. |
| Sulfur (S) | % | ≤ 0.035 | ≤ 0.025 | ≤ 0.025 | Tighter controls in alloy and low-temp grades. |
| Tensile Strength | MPa | ≥ 415 | ≥ 415 | ≥ 415 | Minimum required; varies by grade and spec. |
| Yield Strength | MPa | ≥ 240 | ≥ 205 | ≥ 240 | Minimum required; varies by grade and spec. |
| Elongation | % | See standard | ≥ 30 | ≥ 30 | Minimum values specified in respective ASTM standards. |
| Hardness | HB | N/A | ≤ 163 (A335 P11) | N/A | Often specified for alloy steels; carbon steel may have max HRB. |
| Outer Diameter (OD) | mm | 21.3 – 850+ | 10.3 – 850+ | 21.3 – 850+ | Broad range available; specific to mill capability. |
| Wall Thickness | mm | 2.0 – 100+ | 2.0 – 100+ | 2.0 – 100+ | Varies by schedule and OD. |
| Length | m | Random (5-12m) or Double Random | Random (5-12m) or Cut Length | Random (5-12m) or Cut Length | Standard or cut to specific length. |
| Surface Treatment | – | Bare, Varnished, Black/Red Oxide | Bare, Heat Treated Scale | Bare, Varnished | Protective coatings for storage and identification. |
| Coating / Finish | – | Plain End, Beveled End | Plain End, Beveled End | Plain End, Beveled End | End preparation for welding or threading. |
| Manufacturing Process | – | Hot Finished Seamless (HFS) / Cold Drawn (CDS) | Hot Finished Seamless (HFS) | Hot Finished Seamless (HFS) | Process affects dimensional tolerances and properties. |
| Standard Example | – | ASTM A106 Gr. B Sch. 40 | ASTM A335 P11 | ASTM A333 Gr. 6 | Representative specifications for different service types. |
Packaging & Surface Treatment
Seamless pipes are bundled according to size and grade, secured with steel straps. For protection, pipe ends are often capped, and bundles are wrapped in waterproof plastic or coated paper. The external surface is typically supplied as bare (with mill scale) or varnished. For critical corrosion protection, external coatings (e.g., FBE, 3LPE) and internal linings can be applied as per project specifications. Beveled ends for welding are protected with plastic or steel protectors.
Aliases Names
Seamless Pipe, SMLS Tube, Seamless Hollow Section, Hot Finished Seamless (HFS) Pipe, Cold Drawn Seamless (CDS) Tube.
