How to Select an Orbital Welding System by Tube Size, Wall Thickness and Application

Joint-led system shortlist

Turn the pipe list into measurable joint families

Start with outside diameter, measured wall thickness, material grade and joint drawing. A nominal pipe label is useful for ordering pipe, but it is not the dimension a weld head clamps. For example, NPS 3 pipe has an outside diameter of 88.9 mm, while a tube sold as 3-inch OD measures 76.2 mm. Those two workpieces may require different heads, collets and preparation equipment. Keep nominal size and actual OD in separate columns instead of converting them informally during purchasing.

Schedule is another label that must be resolved before selection. Schedule 40 does not mean a fixed wall thickness across every pipe diameter. Read the material specification or drawing and enter the actual wall in millimetres. Where metric and imperial tubing coexist, record both units but nominate one controlled dimension for fixtures. Include minimum and maximum manufacturing tolerances when the clamp fit is critical.

Build a joint-family sheet with one row for each combination of OD, wall, material and joint form. Add the required quantity and access condition. A straight tube butt joint, a socket joint and a tube-to-tubesheet joint should not share a selection row simply because their tube diameters are equal. This sheet becomes the basis for head coverage, sample selection, program naming and the configuration review. It also makes gaps in a proposed package visible before an order is placed.

Check the complete installation and removal envelope

Head selection is a geometry problem as well as a diameter problem. Confirm the straight clamping length on both sides of a butt joint, the radial clearance around the tube and the space needed to open or remove the head after welding. Nearby elbows, tees, supports and adjoining tubes can obstruct an otherwise correctly sized head. Check these conditions on a dimensioned assembly drawing or a representative mock-up.

Cable, gas and cooling connections also need a route that stays usable throughout the weld cycle. A fitting that clears the closed head at rest may interfere with opening, unloading or the next setup. Show the operator's working position and the order in which the assembly will be completed. A head that fits the first joint can become trapped when another tube is installed beside it.

For dense manifolds, consider smaller suitable heads, subassembly welding and a planned joining sequence. Each option must still match the specified tube OD, wall and joint form. Do not solve an access problem by assuming an unsupported micro-tube range or by changing the joint design without engineering approval. If a special fixture or custom arrangement is needed, describe the geometry and validate it with the proposed equipment.

Include handling in the trial: load the joint, connect services, weld, cool, remove the head and reach the next location. Time and inspect the full sequence. This establishes whether a configuration can be used repeatedly by an operator in the actual assembly, rather than merely showing that the electrode can rotate once around a tube.

Control the end face before changing the weld program

Cutting, facing and beveling perform different jobs. Cutting separates the workpiece at the required length. Facing squares the end and removes unevenness that would disturb fit-up. Beveling creates the groove geometry needed for a prepared, usually thicker-wall joint. Purchasing a cutting machine does not remove the need to verify the final end condition required by the welding procedure.

For a thin-wall autogenous butt joint, inspect squareness, burrs, cleanliness, roundness and alignment before loading the head. A visibly small burr can prevent the ends from meeting evenly. An angled cut can create a gap that changes around the circumference. Correcting current to overcome that local gap may overheat the rest of the joint. Keep the preparation method consistent across samples and production, and protect finished ends from handling damage.

For a prepared open-head joint, follow the specified groove angle, land, root gap and alignment. These dimensions must come from the joint procedure, not from a generic example copied from another pipe size. Confirm that the preparation tool can clamp the actual pipe and leave enough room for subsequent welding. Support long workpieces so that the cut or bevel does not become the point carrying their weight.

Record the preparation tool, blade or insert condition, and any secondary facing step during a trial. If weld results vary, this record helps distinguish a preparation change from a program problem. A repeatable weld starts with a repeatable joint, so end preparation should be part of the equipment package and operator training rather than an unmeasured activity upstream.

PT40 and PT80 solve different tube-to-tubesheet conditions

A tube-to-tubesheet joint is not a tube-to-tube butt joint. The tube end, tubesheet face, pitch and surrounding structure determine how the torch is located and how the joint is accessed. Send a section drawing showing tube OD, wall, material, sheet thickness, tube pitch and the intended end position. Identify whether the connection is a seal weld or has additional structural requirements in the project design.

PT40 pairs with FXT20 and covers OD 10–38 mm with listed wall thickness 0.5–2 mm. It is water-cooled, uses no filler wire and requires a flush tube end. PT80 pairs with 380 V three-phase FXT40 Pro and covers OD 16–80 mm. It supports filler wire and a 0–30° torch angle. Tube protrusion up to approximately 5 mm requires sample confirmation. The present conservative listed PT80 wall range is 0.5–3 mm; a thicker application needs an explicit technical assessment.

The overlapping diameters do not make these heads interchangeable. A 20 mm tube may sit within both diameter ranges while its end position or filler requirement points to a different configuration. Confirm the locating arrangement and access through the tube box, and include neighboring tube holes in the mock-up. The surrounding metal affects the joint differently from a free-standing straight tube.

Validate a representative tubesheet sample, including the required inspection and the operator's move to the next location. Programmed electrode motion should not be described as automatic indexing between tube positions unless the proposed configuration has been confirmed to provide it. Production planning must include re-clamping, inspection and record association for each location.

Check U-tube geometry before comparing cycle time

The FXT20 Pro U-tube system is a distinct configuration using U12, U16, U21 or U25 heads. Its overall OD range is 12.7–25 mm. For socket joints, the combined wall thickness limit is 1.6 mm; for butt joints, the listed wall limit is 1.6 mm. A tube-to-tubesheet PT head or a C-series butt-welding head should not be selected just because the same tube diameter appears in its range.

Each U head has its own clearance and straight-section requirements. U12 has a 24.5 mm clearance radius, requires at least 28 mm straight-tube extension and at least 36 mm straight section on the U-bend. U16 uses a 32 mm clearance radius with 36 mm extension and 44 mm U-bend straight section. U21 uses a 36 mm clearance radius with the same listed 36 mm extension and 44 mm straight section. U25 uses a 40 mm clearance radius, 38 mm extension and 48 mm U-bend straight section. Socket insertion depth is 5–8 mm.

Check these dimensions on the actual joint drawing, including any nearby tubes or supports. Changing insertion depth changes the assembled geometry and may affect both the thermal condition and the room available for the head. Prepare the trial joint exactly as the intended product will be built, with the required internal and external protection.

Before comparing output, confirm that the complete assembly can be loaded and unloaded repeatably. A fast rotation cycle has little value if the head cannot reach or leave the next joint. Validate the selected setup and then measure the full joint cycle under representative production conditions.

Validate representative joints before releasing production

Use sample joints that represent the intended materials, wall thicknesses and access conditions. A convenient straight tube on a bench may be useful for initial setup, but it does not establish that a crowded assembly or a prepared field joint is ready for production. Include the smallest and largest relevant dimensions and any geometry that changes clamping, gas protection or operator access.

Agree the acceptance plan before the demonstration. Identify who reviews external and internal appearance, dimensions and the required tests. Where a project uses a welding procedure specification and qualification records, align the trial with those requirements. A stored machine program is an instruction to the controller; it is not itself a qualified welding procedure or an approval certificate.

Capture the starting condition as carefully as the finished bead. Record material, end preparation, fixture, electrode setup, gas arrangement, power-source version and program revision. If a test fails, classify the observed problem and change one relevant variable at a time. Repeat with a fresh sample and keep the comparison. This approach is more informative than adjusting several settings until one attractive bead appears.

Before production release, repeat the accepted setup over a representative sequence so that handling, cooling, consumable condition and record collection are exercised together. Include head removal and access to the next joint. The result should be an executable setup sheet and an inspection agreement, not simply a successful photograph. Automation improves repetition when the inputs are controlled; it does not remove the need to establish those inputs.

Complete the preparation equipment shortlist

For external-clamping cutting and beveling, compare the 19 electric YDP models from YDP89-E through YDP1230-E. Internal-expanding ISY uses a different clamping dimension: ISY30, ISY80, ISY125, ISY150, ISY250, ISY351, ISY426 and ISY630 are selected by bore ID and wall. PF end-facing has seven plug-in models: PF1, PF1.5, PF2, PF2.5, PF3, PF4.5 and PF6.6. Confirm selected clamp sizes and the blade for the actual tube; PF4.5/PF6.6 dimensions need a configuration check. The full tables in the model specification guide distinguish OD, ID and discrete fixture sizes.

Practical questions

Can the family maximum be used as every head’s rating?

No. Check the individual head’s OD, wall and access requirements. The family range is the combined coverage of several configurations.

How should a nonstandard micro-tube or thick-wall requirement be handled?

A 3.175 mm C-series requirement needs paid customization and technical confirmation. K-series work up to 20 mm wall needs a custom configuration assessment. Neither is treated as a blanket standard rating.

What if the requested joint is not a standard butt joint?

Provide a section drawing and material details. Socket joints, protruding tube ends and other special geometries need a configuration-specific assessment rather than selection from diameter alone.

Can FXT20 export weld logs via USB?

Yes. FXT20 supports USB weld-data export and has a built-in printer. Confirm the exported fields and file format against the supplied software version and associate records with the joint identification.

What closes the selection process?

Confirm the proposed package and demonstrate representative accepted joints using the agreed preparation, services, program and inspection plan.

Discuss your joint and equipment configuration

Send FYID-Feiyide the actual outside diameters, wall thicknesses, material grades, joint drawing, available working space, site voltage and inspection requirements. Include the expected production mix and any sample-test requirement so the head, tooling and operating workflow can be reviewed together. Contact our team, or compare the system selection guide and model specification tables.