Sep 12, 2026Procurement Guides
DN42 Seamless Steel Pipe: Size, Material and Applications
DN42 seamless steel pipe has a 42 mm outside diameter and no seam. Learn its common wall thickness schedules, materials and industries that use it.
Quick answer: DN42 seamless steel pipe is a seamless pipe with an outside diameter of 42 millimetres. Because it is made from a pierced billet and rolled with no weld, it offers excellent mechanical properties and clean inner and outer surfaces, which suits high-pressure, high-temperature, low-temperature and corrosive service.
What a Seamless Steel Pipe Is
Seamless steel pipe is made from steel billets through heating, perforation and rolling. There is no weld on either the inner or the outer surface, so the pipe has excellent mechanical properties and defect-free surfaces. That combination makes it suitable for high-pressure, high-temperature, low-temperature and corrosive environments. In the pipe industry, DN42 is a common specification, and it describes the outside diameter of the pipe.
Dimensions of DN42 Pipe
Size is one of the first things a buyer confirms. DN42 represents an outside diameter of 42 millimetres. Wall thickness is the other key dimension, and the choice depends on the application. Common wall thickness schedules for pipe of this type include SCH10, SCH20, SCH30, STD, SCH40, SCH60, XS, SCH80, SCH100, SCH120, SCH140, SCH160 and XXS. Different schedules suit different working environments and engineering requirements.
Material Options
Three material families are common. Carbon steel is the most common, with good mechanical properties and weldability, and it is widely used in petroleum, chemical, power and aerospace industries. Alloy steel, through the addition of alloying elements, offers higher strength, heat resistance and corrosion resistance, and suits high-temperature and high-pressure environments. Stainless steel is chosen for excellent corrosion resistance and appearance, and it fits fields such as food processing and medical devices.
DN42 defines the outside diameter, not the wall thickness - two DN42 pipes can carry very different pressure ratings depending on their schedule.
Where DN42 Seamless Pipe Is Applied
Oil and gas is a major field: seamless pipe is used in extraction, transport and processing, including oil well casing, oil and gas pipelines and petrochemical equipment. Mechanical manufacturing uses it for automobile and shipbuilding work and metallurgical equipment, typically for high-pressure oil cylinders, hydraulic cylinders and structural components. Construction and bridge engineering use it for support structures, bridge load-bearing members and guardrails. Heat exchangers and boiler equipment rely on its thermal conductivity and high-temperature resistance for tube bundles, boiler tubes and heat pipes. The chemical and metallurgical industries use it for pipelines that carry corrosive media and for structural parts of chemical equipment.
How SPAI STEEL Supplies Seamless Pipe
SPAI STEEL, founded in 1996 and part of the SP Group, exports pipe and tube to more than 100 countries. Seamless and alloy products are made at the Longwan, Wenzhou base, with carbon steel production in Jinghai, Tianjin. Pipes can be supplied to GB, API, ASTM, ASME/ANSI, BS, DIN, JIS and GOST standards, and verified by third-party inspection from SGS, BV, TUV or TUBOSCOPE. Processing services include cutting, slotting, coating, threading, grooving, custom fitting fabrication, packing, marking, warehousing and logistics.
FAQ
What does DN42 mean for seamless pipe?
DN42 indicates an outside diameter of 42 millimetres for the pipe.
Which materials are available for DN42 seamless pipe?
Carbon steel, alloy steel and stainless steel are the common options, each suited to different temperature, pressure and corrosion conditions.
Which wall thickness should I order?
Wall thickness follows the working pressure and environment. Standard schedules from SCH10 through XXS are available, so confirm the schedule with the supplier against your design conditions.
Why choose seamless over welded pipe?
Seamless pipe has no weld seam, so it avoids weld-related defects and is often preferred for high-pressure, high-temperature and corrosive service.
Tell SPAI STEEL the diameter, wall thickness or schedule, material and end use for your seamless pipe requirement. We can confirm a suitable specification and arrange inspection and documentation with your order.
