A circular hollow section (CHS) is a structural steel tube with a round outside profile and a hollow interior. Its geometry gives the same section properties about every axis through the centre, which can be useful for columns, bracing and members exposed to loads from different directions. Structural performance still depends on section size, steel grade, member length and connection design. Understanding Circular Hollow Sections (CHS) What Defines a CHS and How Is It Made? Cold-formed welded CHS can be…

Yes. AS/NZS 1163:2016 is a key product standard for cold-formed, electric resistance-welded structural hollow sections in Australia and New Zealand. It covers circular hollow sections (CHS), among other shapes, and specifies production and supply requirements. Its use on a particular project follows the applicable contract, design and construction requirements; product conformity alone does not establish structural design compliance. Code for Hollow Steel Sections: What Is AS/NZS 1163? AS/NZS 1163:2016 specifies requirements for the production and supply of cold-formed, electric resistance-welded…

How strength toughness member behaviour fabrication and compliance influence grade selection Selecting C250, C350 or C450 circular hollow section is not a matter of choosing the highest yield strength. A suitable grade must be assessed together with section geometry, member slenderness, connection design, service temperature, fabrication procedure, corrosion protection and project documentation. This guide provides a practical comparison for procurement and engineering discussions without replacing project-specific structural design. Understanding the three grade families AS/NZS 1163:2016 with Amendment 1:2017 specifies cold-formed…

A practical guide to strength toughness fabrication and specification for circular hollow sections AS/NZS 1163 C350L0 circular hollow section is widely considered for structural members that require a specified minimum yield strength together with low-temperature impact testing. Its suitability, however, cannot be judged from the grade name alone. Section geometry, member slenderness, connection design, fabrication procedure, corrosion exposure and project-specific compliance requirements all influence performance. This guide explains what the designation means and how engineers and purchasers should evaluate it…

Formulas units worked examples and engineering limits for circular steel pipe The cross-sectional steel area of a circular hollow pipe is the area of the outer circle minus the inner void. This value is used in mass calculations and axial-stress checks, but it is not a complete measure of bending, torsional or buckling performance. Accurate work requires consistent units, the correct diameter convention and a clear distinction between nominal geometry, measured dimensions and design values permitted by the governing code.…

A reliable method for theoretical mass logistics estimates and procurement checks Carbon steel pipe weight is normally calculated as theoretical mass from the specified outside diameter, wall thickness, length and an adopted steel density. The result supports quotations, freight planning and quantity checks, but it is not the same as the measured shipment weight. Coatings, linings, couplings, end preparation, attachments, dimensional variation and packaging must be considered separately when they apply. The standard weight formula For a circular steel pipe…

Circular steel hollow sections are made by forming steel strip or plate into a round profile, joining the longitudinal seam by a controlled welding process, sizing the pipe, and verifying that the finished product meets the ordered structural standard. The exact route depends on the diameter, wall thickness, grade, and mill equipment. This article focuses on round circular hollow sections within LONGMA’s ERW and longitudinal submerged-arc-welded product scope. AS/NZS 1163 covers cold-formed structural steel hollow sections in circular, square, and…

C350 and C350L0 are cold-formed structural hollow-section grades under AS/NZS 1163. They share the same nominal strength level, while C350L0 adds specified Charpy V-notch impact toughness at 0°C. The correct choice is therefore based on the structural design, minimum design temperature, member details, loading, fracture-risk assessment, fabrication, and project specification. C350L0 should not be selected merely because it sounds like a higher-strength grade, and C350 should not be accepted merely because a project is located in a generally warm city.…

API 5L X52 is a line-pipe grade used in pipeline transportation systems. The X52 designation corresponds to a specified minimum yield strength of 52 ksi in the US customary designation; the related SI grade designation is L360. This strength level, combined with established welding and coating practices, makes X52 a common project option for oil, gas, and other pipeline services. It is not a complete purchase specification by itself: buyers must also define the product specification level, manufacturing route, dimensions,…

API 5L Grade B and ASTM A106 Grade B are both carbon-steel pipe materials, but they are specified for different primary purposes. API 5L is a line-pipe specification for pipeline transportation systems and covers seamless and welded pipe. ASTM A106/A106M covers seamless carbon-steel pipe for high-temperature service. Similar grade names do not make the two specifications automatically interchangeable. The current active editions include API Specification 5L, 47th Edition, published in 2026, and ASTM A106/A106M-26. Procurement teams should always use the…

Sour service pipe is steel pipe selected and qualified for service in an H2S-containing environment where hydrogen-related cracking mechanisms must be considered. The term does not simply mean that hydrogen sulfide is present. Material selection depends on the actual service environment, the applicable product specification, the governing material-selection standard, and the purchaser's project requirements. For oil and gas production environments, ISO 15156 provides principles and requirements for selecting and qualifying metallic materials for H2S-containing service. For line pipe, API Specification…

ASTM A252/A252M covers cylindrical steel pipe piles used either as permanent load-carrying members or as shells for cast-in-place concrete piles. One of the most important points for buyers is that ASTM A252/A252M does not create one universal outside-diameter, wall-thickness, or length range for every project. Pipe pile dimensions are selected from structural and geotechnical requirements and then matched to a manufacturer's qualified production capability. The current active edition is ASTM A252/A252M-26. It covers welded and seamless steel pipe piles and…

API 5L PSL2 and sour-service line pipe are related, but they are not interchangeable terms. PSL2 is a product specification level within API Specification 5L. Sour-service pipe adds requirements intended for line pipe exposed to H₂S-containing environments when the applicable project and material-selection rules require sour-service qualification. API published the 47th Edition of API Spec 5L in June 2026, with updates that include sour-service requirements, chemical element ranges, HFW quality, impact toughness and sulfide stress cracking testing. Understanding API 5L…

API Specification 5L covers steel line pipe used in pipeline transportation systems. Commonly specified grades include Grade B and X-grades such as X42, X52, X56, X60, X65, X70 and X80. The X-number is associated with the grade's specified minimum yield strength in ksi, but grade selection should never be based on strength alone. API published API Spec 5L, 47th Edition, in June 2026. ISO 3183:2019, Edition 4, remains current after review and confirmation in 2026; ISO states that this edition…

ERW and EFW describe different welded-pipe manufacturing concepts. ERW/HFW pipe forms strip or coil into a pipe and joins the longitudinal edges by resistance/high-frequency welding and forge pressure without conventional filler metal. Electric-fusion-welded (EFW) pipe uses a fusion-welding process with added filler metal. Longitudinal submerged-arc welded (LSAW) pipe is a common plate-based longitudinal fusion-welded route, but the terms EFW and LSAW should not be treated as universal synonyms. ERW/HFW Pipe: Coil-Fed Resistance Welding In ERW/HFW production, strip or coil is…