Open-Head Weld Head Mapping for 2-10 Inch Pipe Welding in Colombia
A published multi-size pipe enquiry in Colombia discussed open-head options for sizes described as 2, 3, 4, 6, 8 and 10 inches. The sound selection method is to convert those labels into actual OD and wall groups, then map each group to a listed head. The discussion should not be read as proof that one head or every named option has been accepted for the entire job.
Resolve the larger pipe groups without inventing a head rating
The current standard K selection set is K76, K114, K168, K219 and K325. A K273 option appeared in the published discussion, but a current verified K273 rating is not assigned here. If that option is required, obtain its current technical specification before using it in the coverage plan.
For schedule pipe, nominal inch size differs from actual OD. NPS 6 is approximately 168.3 mm OD, which exceeds a K168 upper limit of 168 mm; it should not be rounded down to force a fit. NPS 8 is approximately 219.1 mm, which similarly needs review against the exact head and fixture limit. NPS 10 at approximately 273 mm is within K325's listed diameter range, subject to wall and access checks.
Use the verified head table to allocate each group, then confirm fixtures and procedures. The public account is a procurement-mapping discussion, not measured production performance. A representative multi-size trial should include changeovers and access at the actual job layout.
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.
Where FXT40 Pro and K-series open heads fit
FXT40 Pro with a K-series head addresses open-head industrial TIG welding, including prepared joints that need filler wire and multiple passes. The standard family OD range is 20–325 mm. K76 covers 20–76 mm with a standard wall range of 2–10 mm. K114, K168, K219 and K325 have standard wall ranges of 2–12 mm, with their own diameter coverage. Check the actual head rating before grouping small and large pipe into one package.
The standard three-phase 380 V power-source version provides 10–400 A DC; the optional single-phase 220 V version provides 10–300 A. These are different configurations, so a quotation must identify the intended version rather than combining the current rating of one with the supply requirement of the other. The power source is air-cooled and the K-series head is water-cooled. Site power, cooling connections and the working cable route all need to be included in commissioning planning.
Arc-voltage control and oscillation can help control the process, but arc-voltage control is not automatic seam tracking. Joint alignment, bevel geometry, wire position and the approved pass sequence remain essential. Custom K-series work up to 20 mm wall thickness can be evaluated for a confirmed head, material and procedure; it is not the standard rating of every head. Choose the open-head route because the joint needs its process and access capabilities, rather than assuming that a higher maximum current automatically makes it better for thin clean tubing.
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.
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.
K-series standard head coverage
| Head | Actual tube/pipe OD | Standard wall | Head cooling |
|---|---|---|---|
| K76 | 20–76 mm | 2–10 mm | Water-cooled |
| K114 | 25–114 mm | 2–12 mm | Water-cooled |
| K168 | 60–168 mm | 2–12 mm | Water-cooled |
| K219 | 89–219 mm | 2–12 mm | Water-cooled |
| K325 | 159–325 mm | 2–12 mm | Water-cooled |
Practical questions
Can the nominal 6-inch pipe simply be assigned to K168?
Confirm actual OD. NPS 6 pipe is approximately 168.3 mm, above the listed 168 mm maximum; use an appropriately rated head rather than rounding the dimension.
Is K273 treated as a verified standard model here?
No. Its current rating requires a specific specification review. The listed standard set used here is K76, K114, K168, K219 and K325.
What should a multi-head demonstration measure?
Include sample acceptance, fixture and program changes, preparation, service routing and the complete setup-to-inspection cycle.
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.