Spanish Project Case | ASME B16.5 Class 150 18-Inch SO and BL Flanges -

Project details

Products: 18″ Class 150 Slip-On Hubbed (SO) Flanges and Blind (BL) Flanges
Manufacturing Standard: ASME B16.5 (Pipe Flanges and Flanged Fittings)
Destination: Spain
Client Type: Industrial pressure vessel manufacturer
Application: Pressure vessel shell nozzle interfaces, line isolation, and equipment tie-ins under working pressure; final equipment assemblies destined for the EU market.

Client Requirements

The client builds integrated pressure vessel systems requiring 18-inch Class 150 SO and BL flanges for main shell nozzles. Complete English Material Test Certificates (MTC) and dimensional inspection reports were required for client CE marking documentation files.

Standard Compliance: Strict adherence to ASME B16.5 Class 150 pressure ratings. Sealing faces, bolt circle positions, outer diameters, and wall thicknesses required exact alignment with engineering drawings to match European vessel assembly processes.
Surface Integrity: Machined surfaces required zero blowholes, porosity, sand inclusions, or cracks. Sealing faces required complete protection from mechanical gouges or scratches to ensure pressure containment.
Machining Tolerances: Dimensional tolerances and bolt circle diameter (BCD) pitch precision had to meet EU equipment assembly tolerances to prevent field misalignment during vessel fit-up.
Export Protection: Heavy-duty anti-corrosion protection was required for ocean transit across high-humidity sea routes.

Slip-On Flanges

Blind Flanges

Technical Verification & Parameter Audit

Drawing Review: Engineering teams validated customer PDF drawings against ASME B16.5 parameters over two audit cycles. Verification prioritized outer diameter (OD), bolt hole count, BCD, flange thickness, and raised face dimensions to eliminate standard interpretation discrepancies.

Stock Allowance Management: Raw forging dimensions were measured post-cutting to confirm machining allowances before CNC turning, followed by client re-confirmation of critical dimensions.

Precision Dimensional Inspection: Post-machining, all components underwent individual measurements using digital calipers, vernier calipers, and protractors. OD, thickness, bolt hole diameter, BCD, and sealing face flatness were checked against ASME tolerance limits.

Blind Flange Thickness Audit: Class 150 BL flange plate thickness was audited to ensure adequate structural safety margins under rated design pressure, mitigating wall deformation risks during vessel operation.

Bolt Hole Preparation: All bolt holes received edge chamfers to facilitate smooth bolt insertion and prevent thread damage during field mounting.

In-Process Quality Control

Material Traceability: Heat numbers were verified upon raw material arrival, backed by physical and chemical sample testing to ensure pressure rating compliance and establish full heat-trace archives.
Forging Stress Relief: Forged blanks underwent post-forge heat treatment to eliminate internal stresses, preventing dimensional creep or warping under long-term vessel operating cycles.
CNC Machining: Hub contours, sealing faces, and blind plate surfaces were turned on CNC lathes to achieve required surface roughness values.
100% Inspection: Every unit underwent visual checks for surface defects, micro-cracks, or machining marks. Critical dimensions were recorded individually; non-conforming items were immediately scrapped.
Sealing Face Protection: Machined sealing faces received specialized rust-preventive treatments immediately post-inspection to prevent handling damage and ensure seal integrity.
Stage-Gate Reporting: Production photo documentation was shared at major manufacturing milestones for client sign-off before crating.

Export Packaging & Compliance Documentation

Corrosion Control: Parts were cleaned, sprayed with marine-grade rust-preventive oil, sealed in anti-rust film, and fitted with dedicated face protectors to prevent saltwater corrosion and impact damage.

Crate Specifications: Products were packed into ISPM 15-compliant fumigated solid wood crates featuring internal shock cushioning and external structural bracing for long-haul container transit.

Documentation Package: Each shipment included English Material Test Certificates (MTC), Dimensional Inspection Reports, Packing Lists, and Commercial Invoices to support Spanish customs clearance and EU CE certification compliance files.

Logistics: Shipments were dispatched via containerized sea freight, with real-time transit tracking provided directly to the client.

Receiving Verification & Field Performance

Upon arrival in Spain, the client conducted unpacking inspections. The shipment exhibited zero corrosion or physical damage. All measured dimensions conformed to ASME B16.5 Class 150 standards, bolt hole alignment was exact, and sealing face quality met specification.

The flanges were integrated directly into the vessel shell fabrication process without assembly issues. Based on fit-up precision and product quality, the client placed a repeat order for identical flange specifications and established a long-term supply agreement.