Industrial flanges & gaskets

Flanges to European EN 1092-1 and American ANSI/ASME B16.5 standards, with matched gaskets: spiral wound, PTFE, rubber cloth, jacketed and gas-rated. Stocked in the most common sizes and pressure ratings.

Flange types

Weld neck (WN)

Maximum strength, radiographable butt weld to pipe. For high pressure, high temperature and critical service.

Slip-on (SO)

Economical, easy to align. Fillet-welded internally and externally. For moderate pressure general service.

Blind (BL)

Solid disc to close pipe ends or vessel nozzles. Must resist full design pressure across entire surface.

Lap joint (LJ)

Used with stub end, flange rotates for bolt alignment. Allows economical flange with premium stub end material.

Threaded (TH)

Screws onto threaded pipe, no welding required. For small bores, low pressure, instrument connections and ATEX zones.

Plate/flat (PN)

The most common and economical. Pipe sits on face and is fillet-welded. For low/medium pressure, non-hazardous fluids.

EN 1092-1 (European)

  • Pressure ratings: PN 6, 10, 16, 25, 40, 63, 100
  • Sizes: DN 10 — DN 600
  • Materials: P250GH, 1.4301, 1.4404

ANSI/ASME B16.5 (American)

  • Classes: 150, 300, 600, 900, 1500, 2500 lbs
  • Sizes: 1/2" — 24"
  • Materials: A105, A182 F304/F316/F11/F22

Gaskets for flanged joints

Joint integrity depends as much on gasket selection as on the flange itself. Roffia supplies a comprehensive range of gaskets for every industrial application.

Spiral wound gaskets

The industrial standard for raised-face flanges. Metal strip wound with flexible graphite or PTFE filler. Excellent elastic recovery and sealing even with thermal cycling.

Use: steam, thermal oil, gas, general industrial. EN 1514-2.

PTFE / Teflon gaskets

Virgin or filled PTFE (glass, carbon, graphite) with virtually universal chemical resistance. Inert to nearly all acids, bases and solvents. Low friction coefficient.

Use: chemical, pharmaceutical, food industry. -200°C to +260°C.

Water service gaskets

Elastomer (EPDM, NBR) and compressed fibre gaskets for water mains, water treatment and cooling circuits. Compliant with potable water contact regulations.

Use: waterworks, HVAC, water treatment, closed circuits.

Gas service gaskets

High-integrity gaskets for natural gas, biogas, LPG and compressed air lines. Spiral wound with graphite filler or certified composite materials.

Use: gas mains, biogas plants, boiler houses, compressed air.

Rubber cloth gaskets

Rubber reinforced with cloth inserts (cotton or synthetic) for improved compression and extrusion resistance. Economical and versatile for low/medium pressures.

Use: water, air, non-aggressive fluids. General civil and industrial.

Jacketed (envelope) gaskets

Elastomer or fibre core encased in a PTFE jacket. Combines elastomer resilience with PTFE chemical resistance. Ideal where chemical inertness and good recovery are needed.

Use: chemical, pharmaceutical, food. Aggressive fluids at medium pressure.

Bolting for flanged joints

Correct bolt torque is essential for joint integrity. Roffia supplies complete stud + nut kits in international-standard materials:

  • ASTM A193 B7 + A194 2H — the carbon steel standard
  • A193 B7M — for HIC/SSC (sour service) environments
  • A193 B8/B8M — stainless steel 304/316
  • A320 L7 — for cryogenic and low-temperature service

Domande frequenti

What is the difference between EN 1092 and ANSI/ASME B16.5 flanges?
EN 1092-1 is European, uses pressure ratings in bar (PN 10, 16, 25, 40...) and DN sizes. ANSI/ASME B16.5 is American, uses class ratings in pounds (150, 300, 600 lbs...) and inch sizes. Bolt patterns are different and not interchangeable. In Italy both standards are used: EN for civil and general industrial, ANSI for Oil & Gas and petrochemical. Roffia stocks both standards in Cremona.
Which flange type should I choose?
Depends on pressure, temperature and criticality: slip-on (SO) for low pressure and non-hazardous fluids; weld neck (WN) for high pressure, high temperature and PED-regulated plants — the safest option; blind (BL) for line closures; lap joint (LJ) for frequent disassembly with corrosive fluids.
What gasket to use with flanges?
The industrial standard is spiral wound gaskets (graphite or PTFE) for raised face flanges. For high temperatures (>400°C) use expanded graphite. For chemically aggressive fluids, PTFE. For class 600+ with RTJ face, use metallic ring joint gaskets. Gasket selection is as critical as flange selection for joint integrity.
Does Roffia keep flanges and gaskets in stock?
Yes. Our Cremona warehouse stocks the most requested flanges: slip-on and weld neck EN 1092-1 up to DN 300 in PN 10/16/25/40, and ANSI/ASME B16.5 up to 12 inch in class 150/300. Materials: carbon steel (P250GH / A105), stainless (1.4301 / A182 F304, 1.4404 / A182 F316). We also stock spiral wound, PTFE, rubber cloth, jacketed and gas gaskets in matching sizes. Fast delivery to Northern Italy and all of Italy.
What is a spiral wound gasket and when is it used?
A spiral wound gasket consists of a metallic strip (stainless steel 304 or 316) wound in a spiral with a soft filler, typically flexible graphite or PTFE. The metal strip provides mechanical strength and elastic recovery, the filler ensures sealing. Used on raised face (RF) flanges, it is the industrial standard for steam, thermal oil, gas and process fluids. Reference standard: EN 1514-2. The centering ring aids positioning and can include an inner ring to prevent erosion at high velocities. Roffia supplies spiral wound gaskets in graphite and PTFE in all EN and ANSI sizes.
What is the difference between PTFE gaskets and jacketed (envelope) gaskets?
Solid PTFE gaskets (virgin or filled) are made entirely of polytetrafluoroethylene: they offer universal chemical resistance (-200°C to +260°C) but have limited elastic recovery, requiring precise bolt torque. Jacketed gaskets have an elastomer core (e.g. EPDM, NBR) or fibre core enclosed in a PTFE envelope: they combine the elastic resilience of the core with the chemical resistance of PTFE, compensating better for thermal variations and sealing surface irregularities. Jacketed gaskets are preferred in chemical, pharmaceutical and food industries where both chemical inertness and good adaptability are needed.
What gaskets are needed for natural gas or biogas pipelines?
For gas lines (natural gas, biogas, LPG) gaskets must guarantee absolute gas-tight sealing even at low pressures. Main options: spiral wound gaskets with graphite filler (the standard for RF flanges on gas lines); certified composite material gaskets for combustible gases; gaskets with CE marking and declaration of conformity to gas regulations. For biogas plants with H₂S, avoid non-stainless metallic gaskets and prefer 316 stainless spiral wound with graphite. Gas gaskets must comply with EN 1514 and network operator specifications.
How to choose the right gasket for my plant?
To correctly select a gasket you need: fluid type (water, steam, oil, gas, chemicals), operating temperature (min/max), nominal pressure, flange diameter (DN) and flange face type (RF raised face, FF flat face, RTJ ring type joint). General rules: spiral wound graphite for steam and oil (up to 550°C); spiral wound PTFE for moderate chemicals; solid PTFE for strong acids and bases; rubber cloth for low-pressure water and air; jacketed PTFE for pharmaceutical and food. Roffia's technical team provides free selection assistance: contact us with your process data.

Need flanges or gaskets?

Specify standard (EN/ANSI), type, size, pressure class and material. For gaskets, include fluid and operating temperature. We check stock for immediate availability.

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