Jane Tian

Can 316 stainless steel rust? Yes — 316 stainless steel has strong corrosion resistance, but it is not rust-proof. Under certain conditions, such as prolonged chloride exposure, seawater, surface contamination, or damage at welded areas, 316 stainless steel can still develop rust or pitting over time. Stainless steel has the ability to resist atmospheric oxidation-rust resistance. At the same time, it also has the ability to resist corrosion in media containing acid, alkali and salt-corrosion resistance. Is 316 Stainless Steel More Corrosion Resistant Than 304?   Yes. The addition of molybdenum in 316 stainless steel gives it noticeably better resistance to chloride-induced pitting and crevice corrosion than 304 stainless steel, making it the preferred choice for marine, coastal, and chemical-exposure applications. 304 stainless steel still performs well in dry, low-chloride environments and remains a more economical option for general use. For a full breakdown of the ... Continue reading →

There are two types of steel pipes: square tubes and round tubes. With different shapes and specifications, their performance parameters will also be different. In this article, we compare square tube vs round tube — and square tubing vs round tubing — across strength, bending performance, torsional resistance, applications, and fabrication, to help you choose the right option for your project.   1. Square Tube vs Round Tube Quick Comparison   Factor Square Tube Round Tube Shape Square/rectangular cross-section Circular cross-section Strength Higher bending strength in the axis direction; good rigidity Higher overall stress distribution; better under multi-directional loads Bending Performance Prone to deformation/cracking under bending Better suited to bending and forming Torsional Resistance Weaker torsional resistance Stronger, more even torsional resistance Applications Building structures, vehicle frames, guardrails, load-bearing supports Pipelines, pressure ... Continue reading →

Quick Answer: The Difference Between GI and MS comes down to coating and corrosion resistance. GI (Galvanized Iron) is iron or steel that has been coated with a layer of zinc, which acts as a sacrificial barrier that protects the base metal from rust and moisture damage. MS (Mild Steel) is uncoated low-carbon steel that offers excellent weldability and strength but rusts quickly unless it is painted, oiled, or otherwise protected. Coating: GI has a zinc layer; MS has none Corrosion resistance: GI is excellent; MS is poor unless protected Cost & weldability: MS is cheaper and easier to weld; GI costs more but needs less maintenance In short, when comparing GI vs MS, GI is chosen when long-term corrosion resistance matters more than cost, while MS is chosen when strength, weldability, and affordability are the priority. This same trade-off carries directly into piping products — which is why the choice between GI Pipe vs MS Pipe follows the same logic explained below.   ... Continue reading →

According to the threaded button type drill pipe joints, there are four types: REG(Regular style connection), IF(Internal-flush style connection), FH(Full-hole style connection); NC(Numbered connection) . The drill pipe joint is a component of the drill pipe, divided into a male joint and a female joint, which are connected to the two ends of the drill pipe body. In order to enhance the connection strength of the joint, the wall thickness of the pipe body needs to be increased at the joint. According to the method of thickening, it can be divided into three forms: internal thickening, external thickening, and internal and external thickening. NC is a new series, gradually replacing all IF in the API standard and all FH connectors except 5 1/2" FH. There are several interchangeable with old API connectors, mainly NC50-2 3/8"IF, NC38-3 1/2"IF, NC40-4"FH, NC46-4"IF, NC50-4 1/2"IF. Drill Pipe Connection Types Comparison: REG vs IF vs FH vs NC Feature REG IF ... Continue reading →

A seamless steel pipe is a pipe produced from a solid steel billet without welding or joining. During manufacturing, the billet is heated to a suitable temperature and pierced to form a hollow tube shell. The shell is then rolled and sized to achieve the required diameter and wall thickness. Based on the production method, seamless pipe is generally classified into hot-rolled, cold-rolled, cold-drawn, extruded, and jacking (pushed) pipe. The basic forming principle is: Solid Round Billet → Hollow Tube Shell → Finished Seamless Pipe Because there is no welded joint, seamless steel pipes provide uniform structure and are widely used in applications requiring high pressure resistance and reliability.   Common Manufacturing Methods of Seamless Steel Pipe   Seamless steel pipes can be produced using different manufacturing methods depending on pipe size, material grade, and application requirements. The main methods include:   Manufacturing Method Main Features Hot ... Continue reading →

Carbon steel pipes (CS Pipe) are widely used in industry, but due to their material properties, they are susceptible to corrosion. To protect the service life and safety of carbon steel pipes, effective anti-corrosion measures are necessary. Below, we will introduce several common types of corrosion protection for carbon steel pipes in detail. 1. Paint Protection Paint protection is a commonly used method for protecting carbon steel pipes. By applying paint to the surface of the steel, air and moisture can be isolated, thus achieving the purpose of corrosion protection. Paint protection has the advantages of simple construction and low cost, but it should be noted that the quality of the paint and the application process have a significant impact on the anti-corrosion effect.   2. Galvanizing Protection Galvanizing protection involves coating the surface of the carbon steel pipe with a layer of zinc, utilizing the reactivity of zinc to protect the steel pipe from corrosion. ... Continue reading →

Advantages and Disadvantages of Stainless Steel Pipes   2.1 Advantages of Stainless Steel Pipes:   Good corrosion resistance Stainless steel pipes are composed of chromium, nickel and other elements. They have good corrosion resistance and can withstand the erosion of highly corrosive media such as water vapor, ocean air, acids, alkalis, and salts. They have excellent durability. Especially in highly corrosive environments, stainless steel pipes have better corrosion resistance. Compared with other metal pipes, stainless steel pipes have an extremely long service life, which can save more maintenance and replacement costs. This is also one of the main reasons why stainless steel pipes are widely used in chemical industry, petroleum, medicine and other fields. High strength The strength of stainless steel pipes is higher than that of ordinary steel pipes, and it still has good strength and toughness under harsh conditions such as high temperature, low temperature, and high ... Continue reading →

The full form of ERW pipe is "Electric Resistance Welded pipe." In the steel pipe industry, ERW steel pipe means a straight seam pipe made through electric resistance welding — a fast, low-cost welding process used to move oil, natural gas, and other pressurized fluids. ERW pipe starts as a hot-rolled steel coil. A forming machine bends it into a round shape. Then high-frequency current heats the two edges of the steel using what's called the skin effect and proximity effect — this concentrates heat right where the edges meet. Extrusion rollers press the hot edges together to form the weld. Because the weld comes from melting the steel strip's own material (not filler metal), the seam ends up stronger than in ordinary welded pipe. That combination — fast, automated, low-cost welding — is why ERW steel pipe shows up across so many industries: aviation, energy, automotive, construction, and general fluid transport. 1. ERW Pipe Standards, Size ... Continue reading →

Stainless steel pipe is a hollow cylindrical steel product used across industrial piping and mechanical components, valued for its combination of low weight and high bending/torsional strength.   Classification: By process: Seamless (hot-rolled, cold-rolled, cold-drawn) or welded (straight-seam, spiral) By shape: Round or special-shaped (rectangular, elliptical, hexagonal) — special shapes offer greater bending/torsional strength for structural use By application: Oil well pipes (casing, tubing, drill pipe), line pipes, boiler pipes, mechanical structure pipes, and chemical/process pipes Stainless Steel Pipe and Tube Sizes and Grades   Our supply range for the stainless steel pipe and tube: Standards: ASTM A321, ASTM A213, ASTM A269, ASME SB677 Duplex stainless steel pipe standards: ASTM A789/ ASME SA 789. ASTM A790/ ASME SA 790 Material: AISI 304, 304L, 316, 316L Outer Diameter: 5.8 – 508mm, Wall Thickness: 0.3 – 50mm Read full guide: Stainless Steel ... Continue reading →

ERW vs LSAW vs SSAW: Quick Comparison Table   The table below summarizes how ERW, LSAW and SSAW differ across the factors that matter most when specifying pipe for a project — welding process, size range, pressure rating, cost and the standards each type typically meets. Use it as a quick reference, then check the sections and detailed guides below for the reasoning behind each figure.       ERW LSAW SSAW Full name Electric Resistance Welded Pipe Longitudinal Submerged Arc Welded Pipe Spiral Submerged Arc Welded Pipe Weld shape Straight seam Straight seam Spiral seam Welding process High-frequency induction/contact welding Double-sided submerged arc welding (UOE/JCOE/HME) Submerged arc welding, spiral forming Raw material Hot-rolled steel coil Single medium/thick steel plate Steel coil Typical diameter Small–medium Large Small–large (flexible) Typical wall thickness Thin Thick Medium Dimensional accuracy High High Moderate Pressure resistance ... Continue reading →

1. Advantages of Seamless Steel Pipe Light weight — for a given strength requirement, seamless steel pipe is significantly lighter than solid steel sections of comparable load capacity, giving it good weight-to-strength performance. Corrosion and temperature resistance — resistant to acid, alkali, salt, and atmospheric corrosion; withstands high temperatures, impact, and fatigue without regular maintenance, which helps extend service life in demanding operating environments. High mechanical strength — the absence of a weld seam removes what is typically the weakest point in a welded pipe, giving seamless pipe a strength and reliability advantage under high pressure and cyclic loading, along with strong creep resistance. Easy to fabricate downstream — once formed, seamless pipe machines, cuts, bends, and threads predictably thanks to its uniform, continuous structure — this is a separate question from how difficult the initial seamless-forming process ... Continue reading →

1. Quenching + High-Temperature Tempering   This is the go-to process when a pipe needs both strength and toughness at the same time — a combination that's hard to get any other way. The pipe is first heated until its internal structure turns into austenite, then rapidly cooled (quenched) so it transforms into martensite, a very hard but brittle structure. On its own, martensite would be too fragile to use, so it's followed by high-temperature tempering, which softens it slightly and converts it into a more balanced structure called tempered sorbite. A real-world example helps illustrate why this matters. Pipeline steel like API 5L long-distance oil and gas pipelines that have to survive harsh winters and constant pressure cycling. The tempering step isn't optional. Right after quenching, a steel pipe is carrying more than 300 MPa of internal stress and is dangerously brittle — a small impact could crack it. Tempering removes over 90% of that stress. ... Continue reading →

Can ERW pipe be used instead of CEW pipe?  For general piping and structural use, yes. For applications needing tight dimensional tolerance or a precision bore finish — such as hydraulic cylinders — standard ERW pipe usually won't meet the requirement, and CEW pipe (or DOM pipe) should be specified instead.   ERW Pipe vs CEW Pipe: Quick Comparison     Item ERW Pipe CEW Pipe Definition Steel strip formed and welded by electric resistance ERW pipe that has been cold drawn through a die Raw Material Steel strip (coil) ERW pipe Manufacturing Stage Primary forming (as-welded) Secondary processing (cold drawn) Dimensional Accuracy Standard commercial tolerance High-precision tolerance Surface Finish Mill finish Smooth, cold-drawn finish Common Standard ASTM A53 / API 5L, etc. EN 10305-2 Typical Cost Lower Higher (due to added drawing process) Typical Applications Construction, water/plumbing systems, structural piping Hydraulic cylinders, pneumatic ... Continue reading →

Can ERW pipe be used instead of CEW pipe?  For general piping and structural use, yes. For applications needing tight dimensional tolerance or a precision bore finish — such as hydraulic cylinders — standard ERW pipe usually won't meet the requirement, and CEW pipe (or DOM pipe) should be specified instead.   ERW Pipe vs CEW Pipe: Quick Comparison     Item ERW Pipe CEW Pipe Definition Steel strip formed and welded by electric resistance ERW pipe that has been cold drawn through a die Raw Material Steel strip (coil) ERW pipe Manufacturing Stage Primary forming (as-welded) Secondary processing (cold drawn) Dimensional Accuracy Standard commercial tolerance High-precision tolerance Surface Finish Mill finish Smooth, cold-drawn finish Common Standard ASTM A53 / API 5L, etc. EN 10305-2 Typical Cost Lower Higher (due to added drawing process) Typical Applications Construction, water/plumbing systems, structural piping Hydraulic cylinders, pneumatic ... Continue reading →

DOM tube and CEW tube are both precision tubes produced from ERW (Electric Resistance Welded) tubes through different cold working processes. They are widely used in applications requiring better dimensional control and surface quality compared with standard welded tube. CEW tube refers to Cold Drawn Electric Welded tube, produced by cold drawing an ERW tube through a die to improve dimensional precision and mechanical performance. DOM tube (Drawn Over Mandrel tube) describes a specific cold drawing method in which a mandrel is used during the drawing process, along with removal of internal and external weld flash beforehand. This method provides tighter control of the inside diameter, wall thickness, and overall tube consistency. Although both products start from ERW tube, their drawing methods, applicable standards, and typical applications are different. DOM Tube vs CEW Tube: Quick Comparison   Item DOM Tube CEW Tube Full Name Drawn Over Mandrel Tube Cold Drawn Electric Welded ... Continue reading →

CEW tube stands for Cold Drawn Electric Welded tube. It is a cold drawn welded tube produced from standard ERW tube, designed to achieve tighter dimensional tolerances, improved surface finish, and enhanced mechanical properties. The term CEW refers to the electric resistance welding process used to form the base tube before cold drawing. CEW tubes are commonly manufactured according to EN 10305-2, the European standard for cold-drawn welded precision steel tubes, and are available in diameters from 6.35 mm to 127 mm, including non-standard sizes upon request.   CEW tubes are widely used for hydraulic cylinder applications, especially multi-stage hydraulic cylinders, where dimensional accuracy and surface finish are critical. The manufacturing process is similar to that used for cold drawn seamless tubes, but the base tube is produced through electric resistance welding.   After ERW welding, the weld area is typically heat-treated or normalized to improve structural ... Continue reading →

Finding a defect in a shipment of cold drawn seamless steel tube is only half the problem — the harder question is what to do next. Not every defect is grounds for rejection, and not every defect can be fixed. This guide walks through the practical decisions buyers and quality inspectors face once a defect has been identified: what can be corrected, what can't, and how to tell the difference. Making the wrong call here isn't a small mistake — it can mean unnecessary rejection costs on one end, or an unexpected failure in service on the other. Quick Reference: Which Defects Can Be Repaired?     Defect Category Correctable? Corrective Action Scratches / scoring Surface Yes, if shallow Light grinding or polishing; re-inspect depth against tolerance Scale / oxidation marks Surface Yes Re-pickling or mechanical descaling; re-inspect for residual scale Surface cracks Surface No Reject — treated the same as an internal defect Ovality (out-of-round) ... Continue reading →

What are the Common Defects in Cold Drawn Seamless Steel Tubes? For procurement purposes, it helps to think of tube defects in three buckets: Surface defects — anything visible on the outside or inside of the tube: scratches, folds, scale, corrosion, and surface cracks. Internal defects — problems hidden inside the tube wall, usually inherited from the original steel billet (the solid round bar the tube is made from) or the casting process: porosity, segregation, non-metallic inclusions, shrinkage cavities, and white spots. Dimensional defects — the tube doesn't match the size or shape called out on the order: ovality, wall thickness variation, and straightness deviation. Cracking is the one defect that can land in more than one bucket — it can start at casting (internal), during cold drawing, or later in service (surface). The sections below walk through each category. Surface Defects of Cold Drawn Seamless Steel Tubes A buyer can catch most surface ... Continue reading →

1.1 Piercing Inconsistent piercing temperature and outdated equipment are common causes of uneven heating in the round steel billet during the cold drawn tube piercing process. This creates a temperature gap between the inside and outside of the tube, which shows up later as pitting, pockmarks, or surface peeling — all of which affect inner surface finish. An extended perforation furnace with even heat distribution across the billet helps avoid this problem. 1.2 Cold Drawn Mold Defects in the drawing die itself carry straight through to the finished tube's internal surface. Cold drawing die precision is one of the most direct levers over the result: dies that are worn, poorly machined, or not matched to the specific tube dimensions will produce a rougher inner bore regardless of how well the rest of the process is controlled. 1.3 Pickling Because of tightening environmental regulations, many manufacturers have moved pickling to third-party processors without the accumulated ... Continue reading →

1. Inspect the Surface Finish Start with the surface — it’s the fastest way to spot obvious manufacturing or handling problems, and it doesn’t require any equipment. A clean, smooth finish is usually a good sign; visible flaws can point to bigger issues with corrosion resistance or machining accuracy down the line. During a visual inspection, check the entire length of the tube for the following defects: Surface cracks or fine fractures Scratches and scoring Rust or corrosion Dents or deformation Folds or laps Scale or oxidation marks Pay particular attention to the tube ends and areas where handling damage is most likely to occur. Minor surface marks that do not affect dimensions or performance may be acceptable, but cracks, heavy corrosion, deep scratches, or folds should generally be considered unacceptable unless permitted by the applicable standard or customer specification. 2. Verify Dimensional Accuracy Dimensional inspection confirms whether the delivered ... Continue reading →