Case Study: Achieving Zero-Leak Precision in Belgian Industrial Refrigeration Piping

Industry: Industrial Refrigeration — Cold Chain Infrastructure  |  Location: Belgium, European Union  |  Product: FYID FXT20 + C40 / C80 / C170 Enclosed Orbital Welding System  |  Reading time: 8 min

Background: High-Pressure Refrigerant Piping in European Cold Storage Facilities

Industrial refrigeration systems for cold storage and food processing in Europe operate on ammonia (R-717) or HFC refrigerants at working pressures of 1.5 MPa to 2.5 MPa, through stainless steel piping systems that range from Φ6.35 mm (¼") instrumentation and capillary lines to Φ168 mm (6.6") main distribution headers. At these pressures, a through-wall defect at a weld joint — including a pore of 0.3 mm diameter in the weld root — is sufficient to cause a refrigerant leak that triggers system shutdown, compressor damage from contaminated refrigerant, and in the case of ammonia systems, an environmental incident subject to EU Regulation No. 517/2014 on fluorinated greenhouse gases and the Seveso III Directive for hazardous substance thresholds.

The client in this case study is a Belgian industrial refrigeration contractor with over two decades of experience installing complex cooling and freezing systems across the European Union — cold storage logistics facilities, food processing blast freezers, and pharmaceutical temperature-controlled warehouses. The firm's competitive positioning in the EU contracting market is based on documented quality: every project is delivered with ISO 9001-compliant weld records, pressure test certificates, and system commissioning reports that project owners retain as part of the facility's CE pressure equipment documentation under PED 2014/68/EU.

The firm's previous welding approach — manual TIG with certified welders — had delivered acceptable quality on smaller projects in the Φ12.7 mm to Φ50.8 mm range. On larger projects requiring the full Φ6.35 mm to Φ168 mm diameter range, two problems emerged: certified manual TIG welders capable of producing mirror-finish internal beads on 316L stainless across the full diameter range are scarce in Belgium's tight labour market; and on large-diameter stainless tube (Φ101.6 mm to Φ168 mm) at wall thicknesses of 2.0 mm to 3.0 mm, manual overhead TIG produced first-pass rejection rates of 5% to 8% on borescope inspection — driven by gravitational weld pool sag and inconsistent argon purge coverage in the overhead position.

The Challenge: Zero Oxidation, Variable Diameter, and EU Labour Market Constraints

Internal oxidation in refrigerant piping — the compressor contamination mechanism

Refrigeration system compressors circulate refrigerant oil through the refrigerant circuit for lubrication. When iron oxide scale — the granular black material produced by stainless steel weld inner wall oxidation at temperatures above 400°C without inert gas protection — enters the refrigerant circuit, it is carried by the oil into the compressor bearings and valve seats. Oxide particulate at 10 µm to 100 µm in diameter is the correct size to score compressor bearing surfaces and jam reed valves. Compressor failure from contaminated refrigerant oil is a warranty exclusion under EU refrigeration equipment standards; it constitutes a project liability for the contractor who installed the piping system. The client's zero-oxidation requirement for all refrigerant piping welds was therefore both a technical quality standard and a commercial liability protection measure.

Meeting zero-oxidation on 316L stainless steel refrigerant piping requires maintaining an inert atmosphere at the weld inner wall throughout the full weld cycle and post-flow period — from arc initiation until the metal cools below 400°C. On manual TIG with back-purge, achieving consistent inert gas coverage on large-diameter pipe (Φ101.6 mm to Φ168 mm) requires a purge volume of 0.8 L to 1.5 L at the joint, with controlled displacement from one end and exhaust from the other, maintained throughout a 90-second to 180-second weld cycle. Any disruption to the purge flow — a kinked hose, an insufficiently sealed tube end, or a late purge initiation — produces visible gold or brown discolouration on the inner wall that fails borescope inspection.

Full diameter range from a single power source

The project scope required welding 316L stainless steel refrigerant piping across four OD ranges in a single project phase: Φ6.35 mm to Φ12.7 mm instrumentation and sensing lines (wall 0.89 mm to 1.24 mm); Φ25.4 mm to Φ38.1 mm distribution sub-headers (wall 1.65 mm); Φ50.8 mm to Φ76.2 mm main distribution lines (wall 1.65 mm to 2.0 mm); and Φ101.6 mm to Φ168 mm primary headers and compressor suction and discharge manifolds (wall 2.0 mm to 3.0 mm). Across this range, manual TIG requires different torch sizes, electrode diameters, and gas nozzle configurations — each requiring a qualified operator skilled for that diameter range. A single automated system covering the full range from one power source would allow the client to standardise its operator training programme and its consumable stock across all project diameters.

EU skilled welder availability and training economics

Belgium's certified industrial TIG welder pool has contracted steadily since 2018, driven by demographic retirement of experienced welders and reduced vocational training enrolment in the metalworking trades across the EU. In Belgium's 2024 mechanical contracting market, a certified stainless steel TIG welder with mirror-finish capability on the Φ12.7 mm to Φ168 mm range commands a day rate of €450 to €650 — and is booked 3 to 4 months in advance on major projects. The client's project scheduling was constrained by welder availability, not by site access or equipment delivery. An automated system that could be operated by general operators with 1 day of training would decouple project scheduling from the certified welder bottleneck.

The FYID Solution: FXT20 Power Source with C40, C80, and C170 Multi-Head Kit

After evaluating the full project diameter range and the zero-oxidation requirement, the client selected the FYID FXT20 digital programmable power source with three C-Series enclosed welding heads: C40 (Φ6.35 mm – Φ38.1 mm), C80 (Φ12.7 mm – Φ76.2 mm), and C170 (Φ50.8 mm – Φ168 mm). This three-head kit covers the full project diameter range from a single power source, with head changeover under 10 minutes between diameter ranges.

Enclosed argon chamber — zero-oxidation at all diameters

The C-Series head's enclosed chamber provides 360° argon coverage of both the outer weld zone and the tube inner wall through the head's integrated dual-channel gas system — no separate back-purge line is required. For the large-diameter joints (Φ101.6 mm to Φ168 mm, covered by C170), the enclosed chamber eliminates the most problematic aspect of large-diameter back-purge: the high purge volume and long purge time required to displace air from the large-diameter bore before arc initiation. The C170 head pre-flow cycle — 5 seconds at the standard argon flow rate — establishes full inert coverage of both surfaces before arc initiation on every joint, regardless of diameter. Borescope inspection on the first 20 C170 joints confirmed silver-white internal bead appearance on 316L stainless at all clock positions, including the overhead passes at 180°.

Expert Parameter Library — full diameter range in a single session

The FXT20's Intelligent Expert Parameter Library was loaded with pre-qualified programs for all seven tube specifications in the project scope before the first production shift. The operator inputs tube OD and wall thickness on the 10-inch touchscreen; the system retrieves the corresponding program. For a crew moving between instrumentation line joints (C40, Φ12.7 mm, 0.89 mm wall) in the morning and compressor discharge header joints (C170, Φ168 mm, 3.0 mm wall) in the afternoon, the parameter transition requires selecting a different program and changing the head — total transition time of 12 minutes, versus the 45-minute minimum for a manual TIG operator to reconfigure torch size, electrode diameter, gas nozzle, and current setting for the same diameter transition.

100% duty cycle for extended production phases

The client's project schedule included three intensive production phases — commissioning new cold store sections within active logistics facilities — where minimising downtime was a commercial priority for the facility owner. The FXT20's 100% duty cycle at 155 A, sustained by the integrated 4-litre forced water-cooling circuit, allowed the client's two-person crew to maintain continuous weld output through 10-hour shifts on large-diameter joints (Φ101.6 mm to Φ168 mm, cycle time 90 seconds to 180 seconds per joint) without thermal shutdown. The largest C170 joints at 155 A steady-state current are at the exact boundary of the continuous duty threshold — the water-cooling circuit maintained the power source at thermal equilibrium throughout the production shifts without a single thermal protection event across the full project scope.

CE and PED documentation — ISO 9001 compliance from project day one

The FXT20's built-in micro printer generated a printed weld report for every joint: weld program number, tube OD and wall thickness, current profile by segment (ramp-up, steady-state, decay), travel speed, arc voltage, pre-flow and post-flow times, and timestamp. The client's site supervisor filed each weld report by joint number in a project weld log binder — one binder per cold store section — which was presented to the project owner and the independent inspection body at the pressure test stage as the per-joint welding record required by PED 2014/68/EU for Category II and III pressure equipment. The printed weld report format was accepted by the inspection body as documentary evidence of ISO 9001 weld quality control without additional certification.

Implementation: Site Conditions and Operational Deployment

Ambient conditions in cold store construction environments

Cold store facilities under construction present a specific challenge for welding equipment: ambient temperatures during the commissioning installation phase range from −5°C (in partially operational refrigerated sections adjacent to the work area) to +35°C (in machinery rooms during summer). The FXT20 is rated for operation from −10°C to +40°C ambient, covering the full range encountered on the project. The integrated water-cooling circuit uses propylene glycol anti-freeze in the coolant mix during winter installation phases — a standard modification for cold environment deployment confirmed with FYID-Feiyide's applications team before project start.

European single-phase power supply compatibility

Belgian industrial facilities provide 230V single-phase and 400V three-phase supply at standard distribution panels. The FXT20's 220V ±10% single-phase input at 4.5 KVA (approximately 20 A at 230V) draws from a standard 25A single-phase circuit — available at every stage panel in the cold store construction areas without a dedicated power arrangement. No three-phase supply was required for the FXT20 system, which simplified site power logistics for the client's mobile crew working across multiple cold store sections simultaneously.

Crew configuration and training

The client deployed a two-person crew on the FXT20 system: one lead operator (experienced in pipe fitting and orbital welding, responsible for fit-up quality, program selection, and anomaly flag review) and one assistant (responsible for argon supply management, head changeover, weld report filing, and cooling water level checks). The assistant had no prior orbital welding experience; proficiency on all three head models across the full diameter range was achieved in one day of hands-on training at the client's workshop before project mobilisation. For the C170 head on large-diameter joints — the most technically demanding configuration in the kit — the assistant achieved correct setup, pre-flow verification, and post-flow procedure on the first day of on-site production, under the lead operator's supervision.

Quantified Results

Pressure test results

All welded sections of refrigerant piping were pressure tested to 1.5 times the maximum allowable working pressure per EN 378-2 (Refrigerating systems and heat pumps — Safety and environmental requirements). The test pressure for the high-pressure side of the system was 3.75 MPa. Zero leaks were detected across all 380 welded joints in the project scope — the first time the client had achieved zero-leak hydrostatic test results on a first-test-pass basis across a project of this diameter range without a re-weld intervention.

Compressor warranty compliance

The compressor supplier's warranty documentation specifies zero internal oxidation in the refrigerant piping as a precondition for warranty coverage — contamination from oxide scale voids the warranty on compressor bearings and valve components. The borescope inspection records confirming silver-white weld interiors across all 380 joints were submitted to the compressor supplier as part of the warranty activation documentation. The client's project manager reported that this was the first project on which the compressor supplier's warranty documentation had been activated without a supplemental statement from the supplier regarding oxidation risk mitigation.

Technical Notes for Industrial Refrigeration Contractors Evaluating Orbital Welding

316L stainless steel refrigerant piping — why autogenous orbital TIG is the correct process

316L stainless steel is specified for refrigerant piping in European cold store construction because its molybdenum content (2% to 3%) provides superior chloride corrosion resistance relative to 304 — relevant in coastal European locations and in ammonia refrigeration systems where trace chloride contamination is a corrosion risk. Autogenous orbital TIG on 316L produces a weld with no filler metal addition, meaning the weld metal composition matches the base metal composition — no dilution of molybdenum content in the weld zone. MIG welding or manual TIG with filler wire dilutes the molybdenum content at the fusion line, reducing corrosion resistance in the most critical location of the joint. For refrigerant piping with a design life of 25 to 40 years in a cold store environment, maintaining full 316L composition through the weld zone is a long-term asset integrity argument, not just a short-term quality concern.

Argon purity specification for refrigerant piping orbital welding

The argon purity required for zero-oxidation weld interiors on 316L stainless steel is 99.999% (5N grade) for both the outer shielding channel and the inner bore channel of the C-Series enclosed head. In Belgium and the Netherlands, 5N argon is available from Air Liquide, Linde, and regional industrial gas distributors in 50-litre cylinders at 200 bar — the standard cylinder size for site use. The FXT20 system's argon consumption on large-diameter joints (C170, Φ168 mm) is approximately 0.4 L/min outer shielding plus 0.3 L/min inner bore channel during the weld cycle, plus pre-flow and post-flow consumption: approximately 0.3 m³ to 0.5 m³ per joint total. A 50-litre 200 bar cylinder (approximately 10 m³ usable volume) supports 20 to 30 C170 joints per cylinder, or 60 to 100 C40 joints at smaller diameter argon consumption rates.

EN 378 and PED 2014/68/EU weld documentation requirements

Refrigerant piping in European cold store construction is classified as pressure equipment under PED 2014/68/EU. The equipment category (I through IV) is determined by the refrigerant group and the pipe size. Category II and III pressure equipment requires a quality system assessment by a notified body and per-joint weld records traceable to the welding procedure qualification (WPS and PQR per EN ISO 15614-1 for TIG welding). The FXT20's printed weld report provides the actual parameter record for each production joint — current, travel speed, arc voltage, timestamp — that satisfies the EN ISO 15614-1 traceability requirement for mechanised welding. The 200-group program storage ensures every production weld is executed at the parameters documented in the qualified WPS.

Frequently Asked Questions — FXT20 for European Industrial Refrigeration Piping

Does the FXT20 C-Series enclosed head satisfy EN 378 requirements for zero internal oxidation in refrigerant piping?

EN 378-2 does not specify a welding process requirement for internal surface condition, but does require that welded joints be free of defects that would compromise pressure integrity over the design life. The zero-oxidation (silver-white) internal weld surface produced by the C-Series enclosed head satisfies both the EN 378 integrity requirement and the refrigerant circuit cleanliness requirement specified by European compressor manufacturers as a warranty precondition. The borescope inspection records from the FXT20's weld log (program number, timestamp, and anomaly flag) provide the per-joint traceability that notified bodies accept as documentary evidence of process control for PED Category II and III pressure equipment.

What is the C170 head's maximum continuous output at 100% duty cycle, and is it sufficient for Φ168 mm 316L stainless at 3.0 mm wall?

The FXT20 power source sustains 100% duty cycle at 155 A — the steady-state current required for autogenous orbital TIG on 316L stainless steel at Φ168 mm OD and 3.0 mm wall is approximately 140 A to 155 A in the mid-circumference segments, reducing to 120 A to 130 A in the final decay segment as heat accumulation compensates for the declining driving current. The C170 head at this current operates at the upper boundary of the 100% duty cycle envelope. The integrated 4-litre water-cooling circuit maintains thermal equilibrium throughout extended C170 production runs at this current — as confirmed in the Belgian project across multiple consecutive 10-hour production shifts with zero thermal protection events.

How does the three-head kit handle the transition from small-bore instrumentation lines to large-diameter headers on the same project?

Head changeover between C-Series models — for example, from C40 (Φ6.35 mm – Φ38.1 mm) to C170 (Φ50.8 mm – Φ168 mm) — requires disconnecting the argon hose and cooling water hose from the current head, removing the head from the FXT20 cable connector, connecting the replacement head, and selecting the new diameter's stored program from the Expert Parameter Library. Total changeover time is 8 to 12 minutes. The program transition is a single touchscreen step — the operator selects the new OD and wall thickness from the library; no manual parameter recalculation is required. In the Belgian project, the crew made an average of two head changeovers per shift on days with mixed-diameter scopes, without any quality issues at the first joint after changeover.

Can the FXT20 operate on Belgian 230V single-phase supply without a step-down transformer?

Yes. The FXT20 is rated for 220V ±10% single-phase input — this tolerance bracket (198V to 242V) covers standard Belgian 230V single-phase supply (nominal 230V, tolerance ±10% per EN 50160, actual range 207V to 253V at the supply point). No step-down transformer is required. The FXT20 draws 4.5 KVA (approximately 20A at 230V) — within the capacity of a standard 25A single-phase industrial circuit breaker available at temporary site distribution panels in Belgian construction projects.

What maintenance schedule did the client follow for the FXT20 system across the multi-month project?

The client followed the standard FXT20 maintenance schedule: cooling water level checked and topped up with deionised water at shift start; tungsten electrode inspected and re-ground after every 80 to 100 joints (using the included electrode grinder) or after any arc initiation anomaly; thermal printer paper roll replaced at approximately 70% depletion to avoid mid-shift interruptions; argon hose connections inspected for integrity weekly; and cooling water full replacement every 30 days. No unplanned maintenance events occurred across the project scope. The C170 head's water-cooled torch body — the highest-stress component in the system at the 140 A to 155 A C170 operating current — showed no visible wear at the end of the project on physical inspection.