A closed weld head, a split type weld head and a pipe welding power supply are not three competing products. They answer different parts of one question. The head decides whether the torch can reach the joint and how large a pipe it can encircle. The power supply decides current, arc travel and weld record output. A working orbital welding machine is normally a head-plus-power-supply combination, and the correct evaluation order is diameter and wall thickness first, access second, power supply third.

Buyers entering the Evaluation stage often receive quotations that name only one element of that combination, or that quote the same headline diameter range across several different product families. This guide separates the three configurations using verifiable specifications, then maps them to industries, site conditions and weld geometries so that a shortlist can be built on capability rather than on model naming.

Orbital welding machine assembly area at KEPUNI, Shanghai — heads, power supplies and rotary stands are produced and tested in the same facility.

Why Buyers Compare These Three Configurations at All

The confusion is structural rather than technical. It comes from three recurring patterns in the market:

• Product catalogues are organised by component type, not by complete system. A single catalogue page may list closed heads, split heads, open heads and power supplies side by side.
• Purchase requisitions frequently say “orbital welding machine” when the actual deliverable is a weld head, or a power supply to be paired with heads already on site.
• Diameter ranges overlap. The KEPUNI XD-20PRO power supply is listed at 3.175–168 mm outer diameter and 0.5–3 mm wall thickness, while the 40/80/120/170 Series closed head is listed at 6.35–168 mm outer diameter and ≤3 mm wall thickness. Read quickly, those two lines look like the same product.

The resulting risk is a specification mismatch discovered after delivery: a head with a 25.4 mm ceiling ordered against a project that also contains 88.9 mm sanitary lines, or a power supply ordered against a wall thickness above 3 mm that neither the head nor the supply is listed to cover.

Industry Background: What Is Shifting in Orbital Welding

Two data points frame the current procurement climate. Grand View Research, in a 2026 report, projects the global orbital welding equipment market to reach approximately USD 1.34 billion by 2033. The same analysis states that open weld heads held the largest head-type share in 2025 at 43.1%, and that the semiconductor end-use segment accounted for 20.1% of the market in 2025.

That combination — open heads dominating volume while semiconductor takes the largest single end-use share — explains why so many buyers now compare head types and power supplies together. High-purity work does not only add cleaning requirements; it changes which head geometry is acceptable and which records the power supply must produce.

Standards impose hard limits that no feature list can substitute for. ASME BPE-2024, the bioprocessing equipment standard, sets the acceptance criterion for weld ID concavity at a maximum of 10% of nominal wall thickness, not exceeding 0.38 mm. Whether a configuration can hold that tolerance depends on the head, the supply and the procedure together.

Closed Weld Head, Split Weld Head and Power Supply Defined

1. Closed weld head — 40/80/120/170 Series

A closed weld head is a complete ring that encircles the pipe and rotates the torch around the full circumference. The KEPUNI 40/80/120/170 Series is listed with a pipe outer diameter range of 6.35–168 mm and a wall thickness capability of ≤3 mm. The industries listed against this series are oil & gas, power generation and chemical processing.

Because the ring closes around the workpiece, a free pipe end is normally required: the pipe passes through the head, or the head is positioned before the final joint is closed up. That geometric constraint, not the diameter range, is usually what decides between a closed and a split configuration on a real project.

2. Split type weld head — 5H, 10H and XD-Split

A split weld head opens along its housing and clamps onto the pipe. It can be mounted on pipe that is already positioned, close to a wall, or inside a confined skid. KEPUNI lists three split families with different ranges and different application statements:

Model-level ranges as published by KEPUNI; confirm against the quoted configuration before ordering.

The split family ceiling is 25.4 mm outer diameter and 1.5 mm wall thickness. Buyers who compare only the smallest available diameter (3.175 mm) sometimes assume the split range extends far higher than it does.

3. Pipe welding power supply — XD-20PRO and XD-20W

The power supply is the control unit. It delivers current, controls rotation speed and arc travel, and produces the parameter records that a quality file depends on. KEPUNI lists two pipe welding power supplies:

• XD-20PRO — pipe OD 3.175–168 mm, wall thickness 0.5–3 mm. Industries listed: semiconductor, pharmaceutical, food & beverage, oil & gas, chemical.
• XD-20W — pipe OD 3.175–168 mm, wall thickness 0.5–3 mm. Industries listed: pharmaceutical, semiconductor, chemical processing.

A power supply does not weld on its own. Its diameter and wall thickness figures describe what the paired head and programmed procedure can achieve, which is why the supply range and the head range have to be read together rather than in isolation.

4. Adjacent series that often enter the same tender

Three further families appear in the same procurement packages and should be recognised so they are not confused with the three configurations above:

• Open pipe welding — XD-K Series power supply covers 19–325 mm OD, 2.5–13 mm wall thickness and 5–500 A; the K Series open weld head covers 19–325+ mm OD with 2.5–13 mm wall thickness. Listed industries include oil & gas, pipeline construction, shipbuilding, petrochemical and power generation.
• Girth welding — the XD-GH Series combines a girth weld power supply with a rotary stand, covering 20–960 mm pipe or vessel OD, 2.5–25 mm wall thickness and 5–400 A.
• Tube-to-tube sheet and U-tube — XD-G400 (4.5–65 mm tube OD, ≤5 mm wall), TB-35 (4.5–35 mm, ≤2.5 mm), TB-65 (8–65 mm, ≤5 mm) and the XD-U Series U-tube head (9–25 mm, ≤1.5 mm).

Specification Comparison Table

Read the table as two questions, not one. Rows one to four tell you what the head can reach. Rows five and six tell you what the control side can deliver. A project satisfies both, or the configuration is wrong.

Step-by-Step Selection Process

Step 1 — Fix the outer diameter and wall thickness envelope

Build the envelope from the pipe schedule, not from a single sample joint. If the project contains 9.525 mm instrumentation tubing and 88.9 mm transfer line in the same scope, the split head family tops out at 25.4 mm and cannot cover both. If any joint exceeds 1.5 mm wall thickness, the split head options are excluded regardless of diameter.

Step 2 — Determine whether a free pipe end exists

This is the decisive question between closed and split. A closed head needs the pipe to pass through the ring. A split head clamps on. In plant retrofit work, tie-in welds and repairs inside skids, the joint is usually already positioned, and that alone points to the XD-Split, 5H or 10H family even when a closed head would technically cover the diameter.

Step 3 — Select the power supply against the procedure

Both XD-20PRO and XD-20W are listed at 3.175–168 mm OD and 0.5–3 mm wall thickness. The differentiation therefore sits in application fit and documentation, not in the diameter figure. KEPUNI states that its orbital systems use 12 welding intervals and provide parameter logging or printing for interval data, and that the XD-20W page describes parameter printing for each interval — features that matter where a quality file has to be produced joint by joint.

Step 4 — Check compliance evidence for the target market

Ask for the certificate, not the claim. KEPUNI holds CE certification issued through UDEM, with certificate numbers M.2022.206.C75864 (valid to 2027-07-21) and 6814C50001315201 (valid to 2030-03-16) against EN IEC 60974-1:2022+A11:2022+A12:2023 and EN IEC 60974-10:2021, plus TCF25040101LVDEMC (valid to 2030-04-02) covering EN ISO 12100:2010, EN 60204-1:2018, EN 60825-1:2014, EN IEC 61000-3-2:2019+A1:2021 and EN 61000-3-3:2013+A1:2019. CE addresses machinery safety and electromagnetic compatibility. It does not certify ASME BPE conformity, SEMI cleanliness or 3-A sanitary status — those require project-specific evidence.

CE-EMC certificate 6814C50001315201, issued through UDEM, valid to 2030-03-16 — covers the listed orbital welding machine models.

Step 5 — Validate with a welded sample before committing

A range table confirms geometric fit; it does not confirm a procedure. Request a sample joint in the actual material and wall thickness. KEPUNI sample orders are listed with a 1 unit minimum, 15–20 day lead time, full inspection, a weld sample report and detailed parameter documentation, with custom parameters and special materials (SS304/316, titanium, Inconel) supported.

Use Cases by Industry and Environment

The configuration question resolves differently by sector. The table below maps the documented industry statements and case outcomes to the configuration most often associated with them.

Inspection area for pipe welders and weld samples — geometric fit and procedure validation are checked separately before shipment.

Trade-Offs Buyers Should Not Skip

Every configuration carries a limitation that a specification sheet will not state plainly:

• Split heads trade range for access. The split families reach 25.4 mm outer diameter and 1.5 mm wall thickness. A closed head reaches 168 mm and 3 mm. Choosing split for access means accepting that ceiling permanently, not just for the first project.
• Closed heads trade access for range. A free pipe end or a demountable joint is a construction-sequence requirement, and it can cost more to arrange on a retrofit than the head costs to buy.
• A power supply is not a system. Two supplies with the same stated range can behave differently once paired with different heads, and the total delivered scope should be quoted as a combination.
• Compliance is project-specific. CE certification covers safety and EMC. ASME BPE-2024 concavity limits, SEMI cleanliness and 3-A sanitary status must be evidenced per project.
• Price bands differ widely by tier. KEPUNI's published 2026 price guide positions the XD-20PRO at approximately USD 8,400–8,600 per unit in the mid-to-high segment, while premium EU/US systems for pharmaceutical and semiconductor work are indicated above USD 25,000–40,000. Configuration, not brand alone, drives the difference.

CE certificate M.2022.206.C75864, issued through UDEM, valid to 2027-07-21 — listed against the orbital welding machine range.

Frequently Asked Questions

Conclusion: Choose the Head by Access, the Supply by Control

The three configurations resolve into a short decision rule. Where a free pipe end exists and the work runs above 25.4 mm outer diameter or above 1.5 mm wall thickness, the 40/80/120/170 Series closed head is the applicable family. Where the joint is already positioned or the tube is small-bore high-purity work, the 5H, 10H or XD-Split head is the applicable family. In both cases the XD-20PRO or XD-20W power supply provides the process control, and the combination — not either element alone — is what should be quoted against the procedure.

Verification should follow the same order: diameter and wall thickness envelope, access condition, power supply and documentation, compliance evidence for the target market, and a welded sample in the real material.