Strong, fatigue-resistant connection
Product formFlanges
/ 01 — TECHNICAL OVERVIEW
Weld Neck Flanges
Flanges create detachable, bolted connections between pipes, valves, vessels and equipment. Weld Neck Flanges are selected according to the material grade, flange standard, nominal size, pressure class, facing, bore, wall schedule, dimensions and applicable testing requirements.
NESCO Pipe & Tubes is a supplier, stockist, importer and exporter of industrial flanges in stainless steel, duplex, super duplex, nickel alloys, titanium and copper-nickel.
Weld Neck Flanges feature a tapered hub and butt-weld connection and are commonly selected for high-pressure, high-temperature, cyclic and critical process applications.
How it is made
01
Traceable billet or bar stock is cut and heated for forging.
02
The flange and tapered hub are forged to develop a continuous grain flow around the pressure boundary.
03
Heat treatment is completed to the ordered material specification.
04
CNC machining establishes the bore, hub profile, facing, bolt circle and gasket seating surface.
05
Dimensions, facing finish, material identity and required NDT are verified before marking and protection.
Request reviewed quotation Material documents on request
/ 02 — PRODUCT DETAIL
Built around the specification.
Weld neck flanges use a tapered hub and butt-weld connection to transfer stress gradually from the flange to the pipe. They are commonly chosen for high-pressure, cyclic, high-temperature and critical process service.
Key features01 02 03 04
Bore can be matched to pipe schedule
Suitable for radiographic examination of butt weld
Available in raised face, flat face and ring-type joint forms
Common specification references
STD
ASME B16.5 for standard-size flanges
STD
ASME B16.47 for large-diameter flanges
STD
ASTM A182 for forged stainless/duplex material
STD
ASTM B564 / ASTM B381 for nickel-alloy and titanium forgings, respectively, where applicable
Explore the flanges range
/ 03 — AVAILABLE GRADES
Available Material Grades
NESCO supplies the material families shown below in flange form, subject to flange type, grade, size, pressure class, facing, bore and availability.
Material familyCommon gradesTypical selection context
Stainless Steel304, 304L, 316, 316L, 310S, 317L, 321, 347, 347H and 904L
General process piping, chemical service, pressure and elevated-temperature applications
Duplex Stainless SteelUNS S31803, UNS S32205 (2205), UNS S32750 (2507) and UNS S32760
High-strength applications and chloride-bearing environments
Nickel AlloysAlloy 20, Alloy 28, Alloy 200, Alloy 201, Monel 400, Inconel 600, Inconel 601, Inconel 625, Inconel 718, Incoloy 800, Incoloy 800H, Incoloy 800HT, Incoloy 825, Hastelloy C276 and Hastelloy C22
Severe corrosion, high-temperature and demanding chemical/process service
TitaniumGrade 2, Grade 5 and other applicable grades
Seawater, chemical processing and lightweight corrosion-resistant applications
Cupro NickelCu-Ni 90/10 (C70600) and Cu-Ni 70/30 (C71500)
Marine, seawater, condenser and heat-exchanger systems
/ 04 — SUPPLY & CUSTOMISATION
Define the supply condition.
Final availability depends on the complete combination of material, dimensions, standard, condition, testing and quantity.
ParameterTypical information to specify
01Standard
ASME B16.5, ASME B16.47 or applicable project / drawing requirements
02Size & bore
NPS / DN, bore and pipe schedule where applicable
03Pressure class
Class 150, 300, 400, 600, 900, 1500 and 2500, as applicable to the selected standard and size
04Facing
Raised Face (RF), Flat Face (FF), Ring Type Joint (RTJ) or other specified facing
05Dimensions
Outside diameter, flange thickness, bolt circle, bolt-hole diameter / quantity and hub dimensions, as applicable
06Machining & finish
Bore machining, hub profile, gasket seating surface and specified facing finish
07Marking & inspection
Grade, heat number, size, class, facing, standard, manufacturer identification and specified inspection requirements
/ 05 — DIMENSIONS & SIZE RANGE
Dimensions aligned to the manufacturing route.
Flange size alone is insufficient. The dimensional standard, pressure class, facing, bore and pipe outside diameter should be specified together.
Design inputTypical optionsRequired RFQ detailWhy it matters
Nominal sizeNPS / DNNominal pipe size and applicable standardEstablishes the flange size and dimensional basis
StandardASME B16.5, ASME B16.47, EN 1092-1 or project standardApplicable flange standardDetermines dimensions, drilling, tolerances and rating basis
Pressure ratingClass 150, 300, 400, 600, 900, 1500, 2500 or applicable PN ratingClass / PN rating and applicable standardEstablishes the pressure-temperature rating basis
FacingRF, FF, RTJ or other specified facingFacing type and required facing finishMust be compatible with the mating flange and gasket arrangement
Bore / pipe scheduleStandard bore, bore matched to pipe schedule or specified borePipe OD, wall thickness / schedule and required boreControls weld transition, alignment and internal flow passage
Dimensions / drillingStandard dimensional pattern or project-specificOD, thickness, bolt circle/PCD, bolt-hole size and number where requiredEnsures mating compatibility and correct installation
Material / gradeStainless, duplex, super duplex, nickel alloy, titanium or Cu-NiGrade and applicable material specificationDetermines mechanical, corrosion and temperature suitability
/ 06 — MANUFACTURING STANDARDS
Standards aligned for every order.
The material standard, dimensional standard and project requirements should be stated separately.
ReferenceWhat it coversRole
ASME B16.5Pipe flanges and flanged fittings, NPS 1/2 through NPS 24
Dimensions, pressure-temperature ratings, tolerances, marking and testing
ASME B16.47Large-diameter steel flanges, NPS 26 through NPS 60
Large-diameter flange dimensions, ratings and drilling
ASTM A182/A182MForged or rolled alloy and stainless-steel pipe flanges, fittings, valves and related pressure-system components
Material specification
ASTM B564Nickel-alloy forgings, including applicable nickel, Ni-Cu and nickel-alloy grades
Nickel-alloy material specification
ASTM B381Titanium and titanium-alloy forgings
Titanium material specification
EN 1092-1Circular steel flanges with PN designation
European dimensional and pressure-rating basis
Project specification / drawingNon-standard dimensions, bore, facing, drilling, tolerances, inspection or other project requirements
Order-specific requirements
/ 07 — INSPECTION & TESTING
Evidence before dispatch.
01MTC and forging heat traceability
02NPS, class, OD, thickness and bolt-circle checks
03Bore and hub dimensions
04Facing type and surface-finish verification
05PMI and hardness when specified
06UT or liquid-penetrant examination where ordered
07Marking and face-protection verification
08Testing and inspection arranged to the purchase order, approved ITP or project requirements
PACKAGING & MARKING
Protected and traceable.
01Machined faces protected with covers or non-abrasive separators
02Small flanges boxed; larger flanges secured on pallets
03Threads, RTJ grooves and bores protected from impact
04Heat and piece traceability retained after machining
05Export packages labelled with type, grade, NPS, class and PO
/ 08 — APPLICATIONS & INDUSTRIES
Engineered for demanding service environments.
From process plants to marine systems, NESCO coordinates material, dimensions and documentation around the operating conditions of each application.
01
Process piping connections02
Pressure vessels and nozzles03
Valves, pumps and compressors
04
Refineries and petrochemical plants
05
Power and steam systems
06
Marine and water systems
07
Chemical processing equipment08
Maintenance and shutdown projectsIndustries servedOne supply partner across critical sectors.
/ 09 — WHY NESCO PIPE & TUBES
Built for buyers who cannot leave details to chance.
From specification review to export documentation, NESCO coordinates the technical and commercial details as one complete supply requirement.
01
Specification control
NESCO reviews the grade, product standard, dimensions, condition and acceptance criteria as one coordinated requirement.
02
Multi-material sourcing
Stainless steel, duplex, nickel alloy, copper-nickel and titanium requirements can be combined within one project enquiry.
03
Traceable documentation
Heat numbers, MTCs and agreed inspection records are aligned with the purchase order before dispatch.
04
Inspection coordination
PMI, dimensional checks, NDT and third-party witnessing can be arranged against an approved inspection plan.
05
Value-added processing
Cutting, machining, end preparation, polishing or protective finishing can be reviewed with the base material supply.
06
Export-ready packing
Identification, surface protection and packing are planned around product geometry and the final transport route.
07
Responsive RFQ review
Technical and commercial inputs are consolidated early so queries are resolved before quotation and production.
08
One accountable supply desk
NESCO provides a single contact for material, processing, documentation, packing and delivery coordination.
/ 10 — FREQUENTLY ASKED QUESTIONS
Clear answers before you specify.
Quick guidance on product selection, standards, dimensions, inspection and documentation. For project-specific requirements, NESCO will review the complete enquiry with your team.
01Why is the matching pipe schedule required?
The flange bore and hub transition should match the connected pipe wall to support alignment, welding and stress transfer.
02When is a weld neck flange preferred?
It is commonly selected for higher-pressure, cyclic, elevated-temperature or critical service where a butt-welded connection is appropriate.
03Which flange details are essential for quotation?
State type, material grade, dimensional standard, NPS, pressure class, bore or schedule, facing, finish, quantity and inspection.
04What is the difference between Class and PN ratings?
Class and PN belong to different flange standard systems and are not direct dimensional substitutes. Use the complete selected standard and rating.
05Why must facing finish be specified?
Gasket performance depends on facing type, groove geometry and surface finish. The piping specification should define the required gasket seating surface.
06Can custom flanges be manufactured to drawings?
Yes, subject to approved material, design responsibility, machining drawing, tolerances, testing and quantity.
/ 11 — REQUEST FOR QUOTATION Nesco direct sales desk
Ready to source?Start with the details you already have.
Our team will review the grade, dimensions, testing and delivery requirements together.