This guide covers what MS rectangular hollow section actually is, how sizing and thickness work, where it fits into industrial structures and frameworks, and what to look for when choosing a manufacturer you can actually rely on for consistent quality.
What Is MS Rectangular Hollow Section?
MS rectangular hollow section, often shortened to RHS or MS RHS, is a mild steel structural tube with an empty core and unequal side lengths, meaning the depth and width differ. This unequal shape is exactly what makes it useful. Because one axis is longer than the other, the section carries more bending strength along that longer axis, which suits it perfectly to beams, trusses, and roof support systems where load travels mostly in one direction.
You'll also see it referred to as mild steel rectangular hollow section, rectangular hollow steel section, MS rectangular hollow pipe, or simply rectangular steel tube. All of these describe the same category of structural hollow section, just phrased differently depending on the region or the person you're talking to.
Like its square counterpart, an RHS steel section starts life as flat HR (hot rolled) coil. The coil gets unwound, levelled, and gradually shaped through a series of rollers into a rectangular profile, then welded along its length using ERW, Electric Resistance Welding. After welding, the section passes through sizing rollers and a cooling trough before being cut to standard structural lengths, typically 6 to 7 metres. This is why you'll often see it described specifically as ERW rectangular hollow section, since the welding method plays a real role in the section's consistency and strength.
Why MS Rectangular Hollow Section Works So Well for Industrial Structures
Industrial structures and frameworks tend to favour rectangular hollow section over solid bar or open sections like angles and channels for a few practical reasons.
The shape gives a high radius of gyration relative to its weight, which means you need less steel to achieve the same strength. That translates directly into lower material cost, lighter transport loads, and easier handling on site. Because the surface area is smaller than an equivalent open section, there's also less paint and coating required, which trims labour cost over the life of a project.
Rectangular hollow section also resists torsion and lateral buckling better than open profiles, giving it better stability under wind and dynamic loads. And because the unequal sides let it flex more efficiently along its strong axis, structural engineers can size a rectangular section more precisely for the actual load direction, rather than over-specifying material the way you might with a square section carrying a directional load.
That combination, cost efficiency, strength, and design flexibility, is exactly why rectangular hollow section shows up so often across industrial sheds, storage racks, pipe racks, columns, trusses, and roof support structures.
MS Rectangular Hollow Section Sizes and Dimensions
Rectangular hollow section sizes are described by three numbers together: depth, width, and thickness, usually written as D x B x t in millimetres.
Standard rectangular hollow section dimensions generally start around 40mm x 20mm on the smaller end and extend up to about 96mm x 48mm for heavier structural applications, though larger sizes exist depending on the manufacturer's rolling capacity. Wall thickness across this range runs from 1.0mm up to 4.5mm, giving fabricators flexibility to match section strength to the actual load a beam or truss member needs to carry.
Here's a simplified look at how MS rectangular hollow section sizing typically works, based on common structural ranges manufactured to IS 4923:
| Size (D x B) | Thickness Range | Weight Range (kg/m) |
|---|---|---|
| 50 x 25mm | 1.8mm to 3.6mm | 1.95 to 3.57 |
| 60 x 40mm | 1.8mm to 3.6mm | 2.66 to 4.98 |
| 70 x 30mm | 2.5mm to 4.5mm | 3.60 to 6.02 |
| 80 x 40mm | 2.5mm to 4.5mm | 4.39 to 7.43 |
| 96 x 48mm | 3.2mm to 4.5mm | 6.71 to 9.13 |
As with any hollow section, rectangular hollow section thickness is what really drives weight. Two lengths of the same 60x40mm section can weigh quite differently depending on whether you've specified 1.8mm or 3.6mm wall thickness, even though the outer footprint looks identical. That's why weight per metre, not just the size label, is the figure structural engineers actually calculate against.
Rectangular Hollow Section Weight and Why It Matters
Rectangular hollow section weight isn't just a logistics detail, it's directly tied to structural performance. A heavier section, achieved through thicker walls, carries a higher moment of inertia and section modulus, meaning it can handle greater bending loads before deflecting or failing.
For fabricators and contractors, weight also drives cost and transport planning. Manufacturers typically publish weight in kg/m, and sometimes as metres per metric tonne, so you can quickly work out how much material a given order represents. Cross checking the weight figure against your structural engineer's design load is a simple but important step, since it confirms the section you're ordering actually delivers the strength the design calls for, not just a size that matches on paper.
MS Rectangular Hollow Section Fabrication
Rectangular hollow section fabrication generally involves cutting, welding, and joining sections into frames, trusses, or supporting structures on site or in a workshop. Because RHS sections weld cleanly with standard Mild Steel electrodes and don't typically need preheating, they're relatively straightforward to work with compared to some solid structural shapes.
That said, good MS hollow section fabrication depends heavily on the quality of the raw material. A section with uneven wall thickness, an inconsistent weld seam, or dimensions that drift from the stated tolerance makes fabrication harder and can compromise the finished structure's strength. This is exactly why sourcing from a manufacturer with tight quality control matters just as much as the fabrication process itself.
Choosing a Reliable MS Rectangular Hollow Section Manufacturer
Not every supplier delivers the same consistency, so it's worth knowing what separates a dependable MS rectangular hollow section manufacturer from one that just moves volume.
Start by checking certification. A proper rectangular hollow section manufacturer India buyers can trust should be working to IS 4923, with raw material chemistry controlled to IS 10748. Ask whether every batch is actually tested, using equipment like digital Universal Testing Machines and spectrometers, rather than relying on general claims about quality.
It's also worth asking how integrated the manufacturing process is. An MS hollow section manufacturer that controls the entire chain, from raw HR coil through rolling, welding, and final sizing, at a single facility tends to produce far more consistent dimensions than a supplier sourcing semi-finished tube from multiple sources. This consistency is what determines whether the section you receive actually matches the weight and strength figures on the chart.
Finally, look at surface finish and straightness. A properly straightened, evenly finished section from a trusted structural hollow section manufacturer is noticeably easier to cut, align, and weld during fabrication, which saves real time and material on larger jobs.
SRMB RealFabrica is one such MS rectangular hollow section manufacturer, producing sections in the 40mm x 20mm to 96mm x 48mm range, conforming to IS 4923, as part of the wider SRMB group with over seven decades of steel manufacturing experience. As a Primary Steel Producer classified by India's Ministry of Steel, every batch goes through testing on digital Universal Testing Machines and spectrometers under the company's PAWS Technology framework, covering physical uniformity, accurate sizing, weld quality, and surface strength. As an MS hollow section supplier and MS rectangular hollow section supplier working across architectural, industrial, general engineering, and infrastructural applications, SRMB RealFabrica manufactures its sections at an integrated plant in Durgapur, West Bengal, right from raw billet to the finished, welded section. You can check current sizing charts and specifications on the rectangular hollow section page.
