PT-Series Tube-to-Tubesheet Orbital Welding for Shell-and-Tube Heat Exchangers

Review the sheet sample and the working sequence together

A representative sample should show the actual tube pitch, sheet thickness, surrounding metal and access from the tube box. Include the tube-to-sheet fit and the intended tube end position. A free tube end welded in open space does not establish the same locating or thermal conditions.

Select inspection methods from the joint design and service requirement. Link each location to a weld map and retain the associated program and inspection disposition. Where a failed joint requires repair, agree the access and repair method before production begins.

For throughput planning, measure tube preparation, clamping, gas setup, welding, cooling, movement to the next tube and inspection. Do not assume that the torch's automatic rotation provides automatic movement between tube holes. A measured pilot can identify the value of repeatable positioning and parameters without inventing a universal seconds-per-joint or first-pass percentage.

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 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 current 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.

Treat external shielding and internal purge as separate controls

The weld-head chamber or torch protects the outside of the joint. Internal purge protects the root surface inside the pipe. A shiny external bead cannot establish whether the inner surface received adequate protection. This distinction matters on stainless, titanium and other oxidation-sensitive applications, particularly when the finished internal surface will be difficult to inspect or clean.

Define a purge path with a controlled gas inlet, effective sealing and a suitable outlet. The setup must displace air without creating uncontrolled pressure inside the tube. Check the joints, plugs and hoses for leakage and keep the arrangement consistent during trial and production. When the procedure calls for oxygen measurement, use the specified sampling location and acceptance threshold before starting the arc. A single universal oxygen number should not replace the customer's material and service requirements.

Keep protection in place during the cooling period required by the procedure. Stopping gas immediately after arc extinction can allow the still-hot root to oxidize. Increasing flow indiscriminately is also not a substitute for correcting a leak or an unsuitable outlet. Trial the complete setup, including the actual tube length and any fittings that alter the gas path.

When discoloration appears, check gas quality, leakage, purge time, flow path and post-flow before changing welding current. Record both internal and external observations so that a local shielding problem is not confused with an entire program failure. The objective is to establish a reproducible protected joint, with acceptance judged against the agreed inspection criteria.

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.

Calculate capacity from accepted joints, including preparation

Measure the entire joint cycle: preparation, handling, fit-up, purge, head setup, arc-on time, cooling, unloading, inspection and record handling. Some tasks can overlap between stations; others share an operator or a single fixture. Show those dependencies before estimating hourly output. Multiplying one short welding demonstration by the number of hours in a shift will usually miss the real bottleneck.

Use accepted joints as the output measure. Include failed samples, inspection holds and rework when comparing methods. Separate a proposed calculation from measured production results, and keep the workpiece mix the same in each comparison. A manual weld on a different wall thickness or a different inspection plan is not a useful baseline for an automated process.

The worksheet should include preparation labor, setup and changeovers, consumables, shielding gas, inspection effort and the chosen equipment configuration. Enter costs from the buyer's own operation and a current quotation. Headline equipment prices alone cannot establish payback, particularly where an additional cutting or facing station and new fixtures are needed.

During a pilot, record each cycle stage and the reasons for delays. If purge or clamping dominates, reducing arc-on time may have little effect on completed output. If the power source or head requires cooling pauses, a duty-cycle change may matter. The useful result is a measured capacity model that explains where time is spent and which change improves accepted-joint output. Savings should be reported only after the comparison has been performed on the relevant work.

Practical questions

Can PT40 weld protruding tube ends?

Its confirmed application requires flush tube ends. For protrusion, evaluate PT80 and confirm a representative sample.

Which head supports filler wire?

PT80 supports filler wire. PT40 is a no-filler configuration, so the joint requirement can determine selection even where the OD ranges overlap.

Is PT80 wall thickness unlimited?

No unlimited standard rating is used here. The current listed range is 0.5–3 mm; thicker work needs an explicit technical assessment.

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.