H.E.R.P.S — Materials, Fabrication, Welding, Surface Finish & Tolerances

Revision D Manufacturing & Materials Baseline

HERPS-VOL-19 establishes the controlled design-development baseline for materials of construction, fabrication practice, welding control, examination, surface treatment, coatings, machining quality, dimensional tolerances, bolted-joint preload, identification, segregation, cleanliness, preservation and manufacturing records for the complete HERPS package.

The manufacturing specification preserves the locked hydraulic, mechanical, electrical, structural, thermal and package interfaces established by the wider HERPS Revision D engineering system.

Manufacturing Design Basis

Revision D Materials Governance

Material substitution is not permitted solely on nominal strength equivalence. Any substitution affecting corrosion resistance, weldability, heat treatment, magnetic behavior, galvanic compatibility, fatigue, cavitation resistance, pressure-code compliance, mass, thermal expansion, electrical bonding or dimensional interfaces requires formal engineering review.

• Positive material identification and traceability for critical alloy components
• Material certificates retained for pressure, rotating, lifting and structural primary components
• Duplex, super-duplex and stainless materials protected from carbon-steel contamination
• Mixed-material interfaces reviewed for galvanic and crevice-corrosion risk
• Critical wetted fasteners maintained under controlled material traceability

Unified HERPS Material Schedule

Material Receipt, Traceability & Storage

• Verify purchase order, material grade, dimensions, heat/lot identity, certification and visible condition before fabrication.
• Transfer heat/lot traceability when parent material is cut.
• Segregate duplex, super-duplex, 316L and 304 stainless from carbon-steel contamination.
• Protect journals, bores, seal tracks and hydraulic surfaces from handling damage.
• Store elastomers and gaskets clean, dry and protected from UV, ozone and heat.
• Preserve electrical and BESS equipment according to supplier environmental and ESD requirements.

Duplex 2205 & Super Duplex 2507 Fabrication

Duplex and super-duplex fabrication uses qualified procedures intended to preserve corrosion resistance, phase balance, toughness and pressure integrity while preventing carbon-steel contamination.

• Qualified WPS/PQR required for pressure and wetted duplex welds
• Qualified welding personnel
• Controlled heat input and interpass temperature
• Matched or over-alloyed filler selected through the approved WPS
• Back purging where root oxidation would impair corrosion resistance or cleanliness
• Dedicated stainless tools, brushes and abrasives
• Carbon-steel wire brushes prohibited
• Arc strikes outside approved weld preparation prohibited
• Heat tint removed from wetted stainless/duplex surfaces
• Pickling/passivation or approved equivalent restoration where applicable

Carbon & Alloy Steel Fabrication

• S355 skid and frame fabricated to controlled structural drawings.
• Mounting datums are machine-finished after welding.
• Weld distortion is corrected before equipment alignment.
• 42CrMo4 / 4140 shafting is machined from Q&T stock meeting the specified strength basis.
• Uncontrolled weld repair on finished shafting is prohibited.
• 17-4PH heat-treatment condition is controlled by manufacturing drawing or vendor route.
• Structural weld sizes and NDE remain structural-calculation controlled.

Stainless Process Piping Fabrication

Weld Category & Quality-Level Matrix

Weld Joint Preparation & Execution

• Joint preparations must be clean, dry and accurately fitted.
• Oil, paint, scale and embedded iron contamination are prohibited in weld preparations.
• Root gaps, bevel angles, backing and purge arrangements follow approved WPS and fabrication drawings.
• Weld sequencing controls distortion of casing faces, skid datums, piping and rotating-equipment interfaces.
• Dedicated grinding media are required for stainless and duplex materials.
• Pressure-boundary weld repairs are documented, traceable and re-examined.

NDE & Examination Baseline

Pressure Testing, Leak Testing & Cleanliness

• Pressure-boundary NDE and dimensional release completed before hydrostatic testing.
• Main-water hydrostatic proof baseline: 37.5 bar(g), subject to governing code and material factors.
• Zero visible pressure-boundary leakage.
• Cooling loop pressure/leak testing follows the approved 6 bar-class procedure and purchased-equipment limits.
• Seal-flush lines are flushed and cleaned before final seal connection.
• Standing water is drained where storage or corrosion risk exists.
• No slag, abrasive, swarf, scale, wire, rags, loose fasteners or foreign material remains in completed systems.

Pickling, Passivation & Stainless Surface Restoration

• Heat tint and contamination removed after duplex welding.
• Pickling/passivation or approved equivalent restoration applied where appropriate.
• Chemical-treatment residues removed and neutralized or rinsed as required.
• Passivation is not used to conceal weld defects, embedded iron or inadequate preparation.
• Finished stainless and duplex surfaces remain protected from later carbon-steel contamination and coating overspray.

S355 Carbon-Steel Coating System

Machined Surface Finish Requirements

Dimensional & Geometric Tolerances

Rotating-Component Manufacturing Quality

• Impellers and turbine runner preserve locked OD and bore envelopes.
• Final blade, meridional and camber surfaces remain CFD/prototype controlled.
• Individual impellers are balanced before complete rotor balancing.
• Assembled pump rotor balance baseline is G2.5 or better.
• No uncontrolled material removal is permitted after final dynamic balancing.
• Keyways, shoulders and fillets must remain free from burrs, laps and stress-raising damage.
• Bearing journals and seal tracks remain protected during assembly and shipping.

Bolted Joint, Torque & Preload Policy

HERPS does not apply a universal torque value across the machine. Controlled joints use joint-specific tightening requirements based on fastener material, lubrication, gasket condition, coating, washers and required clamp load.

• M30 casing through-studs use A4-80 or suitable duplex fasteners.
• Motor hold-down baseline uses four M30 fasteners on machined rails.
• Pump feet use two M24 slots per foot.
• Foundation interface carries a 16 × M30 concept anchor baseline.
• Purchased valves and flange joints use the applicable vendor torque requirements.
• Critical stainless fasteners use service-compatible anti-galling practice.

Galvanic Isolation & Mixed-Metal Interfaces

• Duplex 2205 to coated S355 interfaces use isolation where galvanic or crevice risk exists.
• Stainless piping uses compatible clamps or liners at carbon-steel supports.
• A4-80 and duplex fasteners in carbon structures require coating/isolation review.
• Copper electrical conductors use listed bonding hardware while preserving corrosion protection.
• Aluminium and composite equipment uses vendor-approved transition hardware where required.

Permanent Identification & Traceability

• Valves, instruments, rotating equipment and cabinets use permanent engraved or laser-marked stainless tags.
• Critical identification is not adhesive-only.
• Pressure-part heat and lot traceability is retained.
• Main flow paths receive permanent flow-direction identification where required.
• Electrical and BESS hazards receive the applicable permanent warning labels.
• Asset tag identity matches P&IDs, single-line diagrams, BOMs, instrument indexes and as-built records.

Hose, Tubing, Cable & Conduit Segregation

• Main power and VFD motor cables use dedicated power routing.
• DC-link, BESS and supercapacitor circuits use dedicated HV routing.
• Control and instrumentation use separate control/instrument routing.
• Impulse and seal-flush tubing is routed away from hot surfaces, sharp edges, moving parts and HV terminations.
• Cooling piping is not routed over unprotected electrical cabinets or BESS service openings where leakage could create a hazard.
• Final numerical EMC separation remains electrical-study and vendor controlled.

System Cleanliness Requirements

• Main hydraulic path flushed free of weld slag, scale, abrasive, swarf and foreign material.
• Seal-flush system maintains high particulate cleanliness downstream of its 50 µm replaceable filter.
• Bearing lubrication systems remain clean and dry.
• Cooling loop is flushed before final connection to heat-producing equipment.
• Instrument impulse lines are cleaned and protected from contamination.
• Electrical cabinets remain free of swarf, loose wire strands, liquids and conductive debris.
• BESS cabinets remain under supplier-certified contamination controls.

Fabrication Dimensional Control & Datum Transfer

Manufacturing inspection references the Revision D machine coordinate system: X downstream along the machine, Y left when viewed from the intake, and Z upward from the skid datum.

Manufacturing Hold & Witness Points

• H1 — Material receipt and traceability
• H2 — Duplex WPS/PQR and welder qualification
• H3 — Pressure-weld completion before surface treatment
• H4 — Pressure-part dimensional inspection
• H5 — Shaft and rotor machining
• H6 — Rotor balance certification
• H7 — Skid weld completion before machining/coating
• H8 — Skid datum machining
• H9 — Coating completion
• H10 — Hydrostatic and leak testing
• H11 — Final cleanliness and preservation
• H12 — Final as-built dimensional survey

Manufacturing Quality Data Book

• Material certificates and traceability maps
• Approved WPS/PQR documentation and personnel qualifications
• Weld maps, repair logs and NDE reports
• PMI records where required
• Machining inspection reports
• Rotor balance certificates
• Coating preparation and DFT records
• Pickling and passivation treatment records
• Bolt and preload records
• Pressure and leak-test records
• Flushing, cleanliness and preservation records
• Nonconformance and approved engineering disposition records
• Final as-built dimensions and configuration records

Validation-Controlled Manufacturing Requirements

Revision D deliberately does not falsely freeze manufacturing parameters that require final code calculations, qualified procedures, vendor information, structural analysis or site-specific engineering.

• Final duplex WPS heat-input, interpass and filler variables
• Exact pressure-weld NDE percentages and acceptance classes
• Final casing wall and nozzle-reinforcement calculations
• Final structural and lifting-lug weld sizes
• Final valve and flange drilling/face requirements
• Joint-specific final torque values
• Severe-environment final coating specification
• Final electrical cable and conduit separation distances
• Supplier-certified BESS cell and module construction materials

Revision D Engineering Status

HERPS-VOL-19 Revision D R2.0 is a consolidated master design-development manufacturing baseline. It provides coordinated CAD and fabrication input while retaining the validation gates required before IFC, shop or final production release.

Final qualified welding variables, code-specific examination requirements, structural weld sizing, purchased-component dimensions, joint preload values, site coating requirements and other validation-controlled values remain subject to their governing engineering release processes.