Three measurable inputs decide an orbital welding machine configuration: pipe outside diameter (OD), wall thickness, and the clearance the workspace leaves around the joint. Pipe OD and wall thickness determine which weld head can physically be mounted around the tube. The clearance around the joint determines whether a closed head — which travels a full 360° around the pipe — can be installed at all. KEPUNI organizes its orbital welding head range around those two variables: split-type heads (XD-Split Type Weld Head, 5H Series and 10H Series) cover small-diameter, thin-wall joints up to 25.4 mm OD and 1.5 mm wall, while the closed 40/80/120/170 Series covers pipe from 6.35 mm to 168 mm OD with wall thickness up to 3 mm.

Both head families run from the same drivers. The KEPUNI XD-20PRO and XD-20W pipe welding power supplies are each rated for pipe OD 3.175–168 mm and wall thickness 0.5–3 mm. That means the power supply rarely limits a project — the weld head does. Parameter selection therefore starts with the head, and only then confirms that the power supply covers the same envelope.

Problem definition: why the weld head, not the power supply, is usually the limiting component

A parameter mismatch rarely appears during quotation. It appears when the first joint is set up on site, and it usually falls into one of four patterns.

• OD outside the head window. A head rated for OD 6.35–25.4 mm cannot be closed around a 32 mm pipe, and a large-bore head has no usable clamping geometry on 8 mm tubing. The pipe has to sit inside the head's stated OD range, not at its midpoint.
• Wall thickness above the head rating. Split-type heads such as the 5H, 10H and XD-Split are rated to 1.5 mm wall; the closed 40/80/120/170 Series is rated to 3 mm. Beyond those limits there is no rated parameter window for the head, and the weld program has to be improvised on site rather than validated before shipment.
• Clearance ignored. A closed head needs rotational room for its full body around the pipe. On racked pipe runs, close to walls, or inside skids, that room often does not exist — which is exactly why split-type and open heads exist.
• Material treated as an afterthought. Heads in this range are specified for steel and alloy. Stainless 304/316, titanium and Inconel normally require custom parameters and a validated weld sample before production welding starts.

Each of these errors is decided by two numbers and one drawing. Measuring them before the head is chosen removes most of the risk from the selection process.

Industry background: why head-to-pipe matching has become a procurement question

Orbital welding demand is concentrated in industries where the joint, not the pipe, carries the compliance burden. Strategic Market Research values the global orbital welding machine market at approximately USD 1.32 billion in 2024 and projects USD 2.07 billion by 2030. In the same analysis, oil and gas is the largest application segment, holding more than one third of total market share in 2024, while high-purity piping for semiconductor and pharmaceutical production is identified as the fastest-growing segment because of contamination-control requirements.

Published market sizes vary with scope. Estimates for orbital welding specifically range from roughly USD 0.83 billion to USD 1.32 billion depending on whether the scope counts complete systems or only weld heads and power sources (Metastat Insights; Strategic Market Research). Buyers comparing market reports should confirm the scope before comparing the numbers, because the same discrepancy appears in equipment quotations: a head-only configuration and a complete system are not comparable line items.

Regional demand is similarly concentrated. Grand View Research reports Asia Pacific as the largest region in the welding equipment market with a 37.0% revenue share as of 2025, and projects the U.S. welding equipment market to grow at a 4.2% CAGR from 2026 to 2033. Named major players in the orbital welding equipment market include Lincoln Electric, ESAB (Colfax), Swagelok, AMI (Arc Machines, Inc.) and Polysoude, according to Intel Market Research.

KEPUNI is a brand of Shanghai Chuanli Industrial Co., Ltd., a Shanghai-based manufacturer founded in 2014 that produces orbital welding machines, tube-to-tube-sheet welders, open pipe welders, cold welders and orbital cutters. The company operates a 10,000 m² production park with 280 employees, 36 of whom work in R&D, and exports to Europe, Asia, South America, North America and the Middle East. For buyers, the practical consequence of the market shift is that more projects now arrive with tight cleanliness or documentation requirements — and the parameter window, not the machine brand, decides whether those requirements can be met at the joint.

Detailed solution: split heads, closed heads and the specifications that separate them

Split-type heads: XD-Split Type Weld Head, 5H Series and 10H Series

Split-type (open) heads mount around the pipe rather than being slid over the pipe end, which makes them usable on installed pipe runs and inside confined spaces. In the KEPUNI range, three split heads cover overlapping windows.

• XD-Split Type Weld Head — pipe OD 3.175–25.4 mm, wall thickness ≤1.5 mm. Specified for HVAC, plumbing and field service, where a portable orbital welding machine has to be fitted onto existing pipework.
• 5H Series — pipe OD 3.175–15.88 mm, wall thickness ≤1.5 mm. Specified for semiconductor, pharmaceutical and biotechnology applications, i.e. small-bore high-purity lines.
• 10H Series — pipe OD 6.35–25.4 mm, wall thickness ≤1.5 mm. Specified for pharmaceutical, food & beverage and chemical applications, where sanitary joints are standard.

All three are rated for steel and alloy material groups. Where a project uses stainless steel 304 or 316, titanium or Inconel, parameters are customized rather than taken from a default program.

Closed heads: the 40/80/120/170 Series

The closed-head family covers pipe OD 6.35–168 mm with wall thickness up to 3 mm as a single series. A closed head fully encircles the pipe, which produces a stable, fully enclosed arc path on larger diameters and is the standard configuration for oil & gas, power generation and chemical processing piping. The trade-off is clearance: the head needs full rotational room around the joint and cannot be removed laterally once closed, so it is a poor fit for racked or wall-adjacent pipe runs where a split head would still work.

Power supplies: XD-20PRO and XD-20W

Both units are pipe welding power supplies rated for pipe OD 3.175–168 mm and wall thickness 0.5–3 mm. The XD-20PRO is specified for semiconductor, pharmaceutical, food & beverage, oil & gas and chemical applications; the XD-20W is specified for pharmaceutical, semiconductor and chemical processing. Because the power supply envelope is wider than any individual head, the head remains the limiting component of the configuration: a small split head and a large closed head can both be driven from the same supply, but each stays inside its own OD and wall window.

Material and clearance: the two inputs that override the specification table

Material. Every head in the range is specified for steel and alloy. That covers most industrial pipe welding, but not all of it. Where the line is stainless steel 304/316, titanium or Inconel, the parameter set has to be customized, and the practical control is a validated weld sample rather than a catalogue default.

Clearance. This is the input that most often removes a head from consideration even when its diameter range fits. A closed head needs a 360° envelope around the joint; a split head is mounted laterally and works in tighter locations. Two projects with identical pipe OD and wall can therefore need two different heads.

Step-by-step breakdown: matching a weld head to a job in six steps

1. Measure OD and wall thickness on the actual pipe. Use the measured outside diameter and measured wall thickness of the pipe to be welded as the starting point, not the nominal line size.
2. Classify the material. Steel and alloy configurations sit inside standard head ratings. Stainless 304/316, titanium and Inconel are handled as custom parameter sets with a validated sample.
3. Check the clearance envelope. With full 360° access around the joint, a closed head is available. On racked pipe, near walls, or on already-installed runs, select a split-type head instead.
4. Match the head to the OD window. Small-bore high-purity lines point to the 5H Series; general small-diameter work up to 25.4 mm points to the 10H Series or XD-Split Type Weld Head; pipe from 6.35 mm to 168 mm points to the closed 40/80/120/170 Series.
5. Confirm the wall thickness rating. Split heads are rated to 1.5 mm and closed 40/80/120/170 heads to 3 mm. Above 3 mm wall, open pipe welding machines cover OD 19–325+ mm at 2.5–13 mm wall, and the XD-GH Series girth welding machine covers pipe and vessel OD 20–960 mm at 2.5–25 mm wall with 5–400 A.
6. Confirm the power supply and validate the program. XD-20PRO or XD-20W, both rated OD 3.175–168 mm and wall 0.5–3 mm. Validate the parameter set against a weld sample before production welding begins.

Use cases: how the same parameter logic plays out across industries

Semiconductor and electronics. Ultra-pure gas (UPG) distribution and DI water loop piping is welded under Class 1 cleanroom conditions, with SEMI F57 cleanliness as the governing requirement and 24/7 operation as the norm. The 5H Series split head (OD 3.175–15.88 mm) matched to an XD-20PRO covers most of this scope. In one fab project, four units including XD-20PRO high-purity configuration and tube-sheet heads were supplied in the USD 60K–130K range, with SEMI F57 particulate levels verified and no particle exceedance events recorded.

Pharmaceutical. WFI (Water for Injection) piping and CIP/SIP systems demand aseptic pipe welding, 100% leak-proof joints and traceability, usually under 3A Sanitary Standard, FDA-compliant and EU GMP documentation requirements. A 10H Series head driven by an XD-20PRO is the typical configuration. In a documented project using three XD-20PRO units with weld heads in the EUR 50K–100K range, the EU GMP audit passed on first inspection with zero weld defects and weld quality traceable to each joint.

Food and beverage. Sanitary piping for milk, juice, beer and similar products is welded to EHEDG principles with no dead-leg design and USDA/FDA audit readiness. The 10H Series (OD 6.35–25.4 mm, wall ≤1.5 mm) is the standard match. A dairy project using two XD-20PRO units obtained 3A sanitary certification, achieved a 100% hydrostatic test pass rate and completed installation one week ahead of schedule.

Chemical and petrochemical. Process piping for aggressive media handling carries ATEX/IECEx requirements where applicable, plus API standards and NACE compliance. Larger diameters push the choice toward the closed 40/80/120/170 Series driven by the XD-20W. A five-unit project welding SS316L and Duplex stainless steel process piping for acid transfer and solvent recovery met API 582 welding requirements, completed NACE MR0175 material verification and recorded zero leak incidents.

Power generation and boiler tube. Boiler tube and heat exchanger pipe welding is governed by ASME Section IX, the Pressure Equipment Directive and customer-specified codes, with high-temperature-resistant, pressure-rated welds as the functional requirement. In one project, boiler water wall tube-to-tube sheet welds and superheater tube replacement in a 300 MW thermal plant passed 100% ultrasonic testing and let the plant reconnect four days ahead of the scheduled shutdown window.

Oil & gas, water treatment and heavy industry. Where pipe OD stays within 168 mm and wall within 3 mm, the closed-head family plus an XD-20PRO or XD-20W remains the practical choice. Where the pipe grows beyond that — large-bore SS316L, for example — open pipe welding machines and the XD-GH Series take over. A water treatment project welding SS316L large-bore pipe girth welds to ASME B31.3 recorded zero rework on more than 400 girth welds and delivered two weeks early.

HVAC and heat exchangers. Tube-to-tube sheet orbital welds for industrial shell-and-tube heat exchangers sit at the boundary of this guide: they use a different head family (TB-35 and TB-65 tube sheet weld heads, plus the XD-U Series for U-tube geometry) rather than the pipe welding heads discussed above. In a documented HVAC heat exchanger project, TB-65 and XD-U Series heads delivered ASME U-stamp certified joints with a 100% helium leak test pass.

Comparison tables

Table A compares the four weld head families by parameter window. Table B compares the two compatible power supplies. Table C maps typical applications to a starting configuration.

Table A — KEPUNI orbital welding head parameters

Table B — Compatible power supplies

Table C — Application to starting configuration

FAQ

Conclusion: parameters first, then the machine

Weld head selection is a short calculation once the inputs are measured. Pipe OD and wall thickness place the joint inside a specific head window: split heads up to 25.4 mm OD at 1.5 mm wall, closed 40/80/120/170 heads from 6.35 mm to 168 mm OD at up to 3 mm wall, and open-head machines beyond that. Workspace clearance then decides between a closed head and a split head even when both fit the diameter. Material decides whether a standard parameter set applies or a custom, sample-validated one is required. The power supplies at the end of the chain — XD-20PRO and XD-20W — cover the full 3.175–168 mm range, so they rarely constrain the decision.

Buyers who run this sequence before requesting quotations avoid the most expensive orbital welding error: discovering on site that the head cannot be mounted, closed, or used within its rated wall thickness.