Spiral Heat Exchangers (SHE) NDT Guide
Authoritative engineering guide for Type 1 counter-current and Type 2 cross-flow Spiral Heat Exchangers. Inspect concentric curved plate channels, slurry erosion, circumferential edge welds, and cover gasket seals.
Single curved channel flow increases local velocity at deposits, creating a continuous self-cleaning effect in pulp, paper, and wastewater service.
Spiral Heat Exchanger Design Classifications
Engineered with two concentric metal sheets wrapped around a central manifold core.
Type 1 Spiral Exchanger
Features two continuous curved spiral channels wrapped concentrically. Fluid flows in true counter-current, creating a single-path self-cleaning flow effect ideal for heavy slurries, wastewater, and fouling fluids.
Channel wall thickness measurements via UT, spiral edge seal weld penetrant testing (PT), and cover gasket seating area inspection.
Type 2 Spiral Exchanger
One fluid flows spirally in a closed channel, while the second vapor or gas stream flows cross-wise through the open spiral core. Widely used as overhead condensers and reboilers in distillation columns.
Vapor entrance zone erosion sizing, condensate outlet nozzle weld UT/RT, and shell-to-spiral plate attachment weld inspection.
How B2B Project Workflow Works
From initial RFP scope to direct client sign-off. NDT EXCHANGE does not charge commissions or manage project payments.
RFP Scope
Asset Owner posts turnkey B2B inspection scope with technical specifications, asset list, and required NDT methods.
Competitive Bids
Certified NDT agencies submit competitive proposals (Fixed-Bid / T&M) detailing technician rosters and day rates.
Direct Settlement / Escrow
Client awards bid and sets up direct milestone payment or escrow — NDT EXCHANGE never holds or manages project funds.
Field Execution
Level II/III inspectors perform on-site testing (PAUT, TOFD, MFL, UT), capturing flaw data and calibration overlays.
Sign-Off & Payout
Level III auditor reviews findings; upon client sign-off, funds release directly to agency with 0% platform commission.