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Q355B Steel Pipe Truss with CHS Welded Joints for Roof Structures and Steel Frame Buildings
| MOQ: | 1 PCS/20 Tons |
| Price: | $1300-3000 |
| Standard Packaging: | Sea-worthy bundles; main frames and crane beams in 40 ft open-top |
| Delivery Period: | 30-60 Days |
| Payment Method: | L/C,D/A,D/P,T/T |
| Supply Capacity: | 15,000 t / month |
Q355B Steel Pipe Truss
,CHS Welded Joints Pipe Truss
,Roof Structures Steel Pipe Truss
Pipe Trusses — Tubular Members and Profiled CHS Joints
CHS members • K, T, X and KK joints • Q355B • EN 1993-1-8 / GB 50017 / AISC 360
The tubes in a pipe truss are a commodity. Any fabricator can buy CHS. What separates one truss from another is the joint: whether the brace end is cut to the right saddle curve, whether there is room to weld it, and whether the chord wall is thick enough not to dent before the member reaches its capacity.
A pipe truss member buckles at the same load in every direction, so a compression member does not need to be oriented. That is the single biggest reason a truss chord is round: the designer does not have to think about which way the weak axis is pointing.
Two more follow. A tube has a low drag coefficient, which matters on an exposed roof in a windy site. And a closed section is stiff in torsion, so a truss that also carries a curved or asymmetric roof behaves better than one built from angles.
What you pay for is the joint. An angle truss is gusset plates and bolts; a tube truss is a profiled cut, a fit-up, and a weld that has to be made in a tight corner.
Three numbers decide whether a CHS joint works, and none of them is the member size.
- β = d₁/d₀ — the brace diameter over the chord diameter. Too small and the brace punches into the chord; too large and the two braces collide.
- γ = d₀/2t₀ — the chord radius over its wall thickness. A thin chord wall governs the joint long before the member is fully stressed.
- Gap and eccentricity — a gap between the brace toes of at least 50 mm is the usual rule, so that both welds can be made. Eccentricity at the node is kept within a fraction of the chord diameter, or the joint picks up a moment nobody designed for.
The governing failure is usually chord plastification — the chord wall dimples under the brace — not a weld fracture. That is why a joint is checked against EN 1993-1-8, GB 50017 or AISC 360 Chapter K rather than by looking at the weld size.
A brace end on a round chord is not a square cut. It follows a saddle curve that changes with β and with the angle, and it is cut on a CNC pipe profiling machine. The cut face is then bevelled for a full-penetration weld.
Hand cutting and grinding leaves a gap that varies around the circumference. The welder fills it, the weld looks acceptable, and the joint has a stress concentration nobody can see. The profile is the quality of the joint.
A node is a ring of welds that all pull toward each other. Weld one side first and the node closes; the chord goes out of line and the truss loses its geometry.
The control is a sequence: balanced welding around each node, node-by-node rather than member-by-member, with the truss restrained on a jig. On a large truss the sequence is written into the fabrication plan before the first cut.
A long pipe truss is built with camber so that it deflects to level under its own weight. The camber is set in the jig, not bent in afterwards.
Member length tolerance accumulates from one node to the next. On a truss with more than a few panels, the only reliable check is a trial assembly of the node segments before painting — assembled, measured, match-marked, then taken apart for shipping. It costs a day in the shop and saves a month on site.
Trusses travel as node segments with loose members, or as bolted splices at the panel points. A 40 m truss does not fit in anything, so the splice positions are chosen with the transport route in mind.
Site connections are usually bolted at the nodes, with the bolt holes drilled in the shop from the trial assembly. That is another reason the trial assembly matters: it is where the holes are proven to line up.
- 1Truss geometry: span, depth, panel length, and the number of trusses
- 2Chord and brace diameters and wall thicknesses, or the member design
- 3Joint type: K, T, X, KK, and whether the node is welded or bolted on site
- 4Grade and standard: Q355B, EN 1993-1-8, GB 50017 or AISC 360
- 5Camber, and the deflection limit it is designed against
- 6Surface: primed or galvanized; fire protection if specified
- 7Transport limits, so the splice positions can be set
Send these and we return the node details, the weight and a quotation.
Because a round tube buckles equally in every direction, resists wind better, and is stiff in torsion. The trade is the joint: a profiled cut and a tight weld instead of a gusset plate.
Two braces meeting a chord on the same plane, one on each side of the node, so the joint looks like a double K. It is common on stadium roof trusses and it needs a heavier chord wall than a simple K.
On a CNC pipe profiling machine, to a saddle curve that depends on the diameter ratio and the angle. Hand cutting leaves a variable gap and a hidden stress concentration.
At least 50 mm between the brace toes in normal practice, so that both welds can be made and inspected. If the geometry cannot give that gap, the joint has to be designed as an overlap instead.
Yes, for multi-panel trusses. Node segments are assembled on the jig, measured, match-marked and then taken apart for shipping. It is also where the site bolt holes are proven.
Yes, with vent and drain holes at the design stage. A sealed tube traps air and can be dangerous to dip, and a sealed node cannot be coated inside.
In segments with bolted splices at the panel points, sized to the container or to the break-bulk envelope. The splice positions are set by the route, not by the structure.
Send the geometry, the member sizes and the joint type. We return the node details, the weight and a quotation.
