RFQ Today
Certifications available: EN 10204 3.1 / 3.2 MTRs, pressure test certificates, material traceability, Third-Party Inspection available, and complete EPC and industrial export documentation packages.
Pneumatic
Fittings
A world-class technical reference for EPC contractors, instrument and process engineers, procurement heads, maintenance engineers, and global project buyers specifying pneumatic fittings — push-in tube fittings, compression fittings, NPT and BSPT threaded fittings, barbed fittings, manifold blocks, quick-connect couplings, and silencer / exhaust fittings for compressed air, inert gas, nitrogen, instrument air, and pneumatic control systems across Oil & Gas, Power Generation, Petrochemical, Offshore, Pharmaceutical, Food Processing, and Industrial Automation sectors.
Fitting Type Classification
& Connection Principles
Pneumatic fittings are pressure-rated connection devices that join pneumatic tubing, hose, or threaded ports to create leak-free compressed air and gas circuit connections — enabling the distribution of pneumatic power and instrument air throughout industrial systems with easy assembly, reliable sealing, and field serviceability.
1.1 — Technical Definition and System Context
Pneumatic fittings are used in compressed air and gas systems operating typically at 4–16 bar (58–232 psi) gauge pressure — significantly lower pressures than hydraulic systems (100–700 bar) but requiring the same engineering rigour for leak integrity, because: (1) compressed air leaks are an energy waste — a 3 mm hole at 7 bar gauge in a compressed air system leaks approximately 1.8 m³/min of free air, costing thousands of dollars per year in compressor energy; (2) pneumatic systems for instrumentation and control require zero-leak connections — a leaking instrument air supply to a control valve actuator creates spurious valve movement and process upsets; and (3) in hazardous area classified zones (ATEX Zone 1/2, IECEx), any leak of compressed flammable gas (nitrogen-purged instrument air in sour service, hydrogen gas systems) creates an explosive atmosphere.
Pneumatic fittings serve multiple connection functions in industrial compressed air systems: tube-to-tube connections (push-in, compression, or barbed fittings); tube-to-manifold connections (push-in fittings into manifold blocks); tube-to-equipment connections (NPT or BSPT threaded fittings into valve actuators, cylinders, and instrument ports); directional changes (elbow, tee, and cross fittings in push-in or threaded variants); size transitions (reducing fittings, adaptors); and system isolation (push-in fittings with integrated check or shut-off valves).
1.2 — Pneumatic Fitting Type Classification
Push-In (One-Touch / Instant) Fittings
The most widely used pneumatic fitting type in industrial automation — tube is inserted into the fitting body and an internal collet (grab ring with inward-facing stainless steel teeth) grips the tube OD and creates a mechanical lock. A stainless steel collet ring bites into the tube surface as the pneumatic pressure load pushes the tube toward the release direction — the pressure creates a self-sealing effect: the higher the pressure, the tighter the tube grip. Released by pressing the collet release button/ring while extracting the tube. Compatible with polyurethane (PU) tubing, nylon PA12 tubing, and semi-rigid LDPE or HDPE pneumatic tube. Not for use with soft rubber hose — the collet requires a rigid tube OD to grip against. Working pressure: 0–16 bar (0–232 psi) at ambient temperature per ISO 14743.
Compression Fittings (Ferrule / Bite-Type)
A two-part compression fitting — a ferrule (olive or compression ring) compresses onto the tube OD as the nut is tightened, creating a metal-to-metal seal between the ferrule, the tube OD, and the fitting body cone seat. Single-ferrule (Parker CPI/A-LOK equivalent) and double-ferrule (Swagelok / Parker FK equivalent) designs. Used for: semi-rigid copper, stainless steel, and rigid nylon tubing; instrument air connections where the permanence of a compression connection is required; and high-cycle and high-vibration applications where push-in collet connections may fatigue. Working pressure: up to 100+ bar for stainless compression fittings — significantly higher than push-in fitting capability. Per ISO 8434-1 (stainless compression fittings).
NPT / BSPT Threaded Fittings
Threaded pneumatic fittings with NPT (ASME B1.20.1 — tapered thread, 60°, seals on thread flanks) or BSPT (ISO 7-1 — tapered thread, 55°, seals on thread flanks) for direct connection to tapped ports in pneumatic cylinders, valve actuators, air preparation units (filters, regulators, lubricators), and manifold blocks. NPT and BSPT are NOT interchangeable — they differ in thread pitch, angle, and taper geometry; forcing an NPT fitting into a BSPT port (or vice versa) damages both components and creates a leaking connection. PTFE tape or anaerobic thread sealant (Loctite 565) is applied to all tapered threaded pneumatic connections. Available in brass, nickel-plated brass, SS 316, and carbon steel in ⅛” BSP through 2″ BSP.
BSPP (Parallel) Fittings with O-Ring Face Seal
BSPP (ISO 228 — G-series, parallel thread, 55°) fittings sealed by compression of an elastomeric O-ring (or bonded seal washer) on the flat face at the port entry — the parallel thread holds the fitting in axially; the face O-ring provides the pressure seal. Not sealed on the thread flanks like BSPT/NPT — PTFE tape on BSPP threads does not provide a reliable seal; the face O-ring or bonded washer is the seal. BSPP is the standard pneumatic port thread in European and international industrial automation equipment. The combination of BSPP port and O-ring face seal provides a repeatable, low-torque, leak-free connection ideal for the high-cycle assembly operations typical of pneumatic component manufacturing.
Barbed Fittings (Hose Barbs)
Fittings with a barbed (serrated) shank that inserts into flexible tubing or hose — the barbs bite into the hose inner bore and resist pull-out. Used for: flexible air hose connections (low pressure, ≤ 8 bar); pneumatic tool supply connections; light-duty air blow-gun hose connections; and general compressed air distribution in workshops and light industrial settings. Not suitable for precision instrument air or control systems — the barbed connection provides no positive leak-tight seal at higher pressures without a hose clamp or compression ring. Available in brass and nylon in ⅛”–1″ hose IDs. For higher-pressure hose connections: push-lock (swage) fittings with a serrated barb and outer sleeve provide a higher-integrity connection than bare barb-and-clamp.
Quick-Disconnect Couplings
Push-to-connect, pull-to-release coupling pairs for temporary or frequently disconnected pneumatic connections — tool connections, jig and fixture air supply, portable pneumatic equipment, and maintenance supply points. Half-coupling plug (male, connects to the tool) and half-coupling socket (female, connects to the supply line). Internal poppet valve closes both halves on disconnection, preventing air loss. Available in several coupling standards: CEJN (European standard), ARO/Industria (US), Milton (US), and Nitto Kohki (Japanese/international). Coupling standards are NOT interchangeable — CEJN and ARO sockets accept only their own plug profiles. Specify the coupling series clearly — a jobsite with mixed coupling standards requires adaptors or cannot interchange tools between supply points.
1.3 — Thread Form Incompatibility Table
1.4 — Flow Rate, Cv, and Pressure Drop Principles
Cv = Flow coefficient of the fitting (dimensionless) — published by fitting manufacturer
ΔP = Pressure drop across the fitting (psi)
G = Specific gravity of the gas (air = 1.0; nitrogen ≈ 0.97)
T = Absolute temperature of the gas (°R = °F + 460)
For compressed air in metric units — ISO flow factor Kv:
Kv (m³/h water) = 0.865 × Cv ΔP (bar) = (Q_air / Kv)² × ρ_air / ρ_water
Typical Cv values for pneumatic push-in fittings:
Straight union, tube OD 6 mm: Cv ≈ 0.08 | Elbow 6 mm: Cv ≈ 0.05
Straight union, tube OD 10 mm: Cv ≈ 0.25 | Tee 10 mm: Cv ≈ 0.15
Straight union, tube OD 16 mm: Cv ≈ 0.65 | Elbow 16 mm: Cv ≈ 0.40
Note: Elbows and tees typically have Cv = 0.6–0.7× the straight union Cv for the same tube size.
Q = 100 L/min = 26.4 US gal/min; Cv (6 mm elbow) ≈ 0.05; G = 1.0; T = 530°R (70°F)
ΔP = (26.4 / 0.05)² × 1.0 × 530 / 520 = 277,000 × 1.02 ≈ 282,000 psi — obviously non-subsonic: use compressible flow equations
For real-world pneumatic system design: use the fitting manufacturer’s published Cv tables and their pneumatic flow calculator — the simplified Cv formula applies only to subsonic (non-choked) flow conditions.
Submit your tube OD, connection type, thread form, working pressure, material, and quantity for a documented RFQ within 24 hours.
Working Pressures
& Standards Compliance
Pneumatic fitting dimensions, thread forms, and working pressures are governed by ISO 14743 (push-in), ISO 8434 (compression), ISO 7-1 and ISO 228 (thread forms), ASME B1.20.1 (NPT), and manufacturer dimensional series. All applicable standards are supported at RR Hydraulic.
Submit tube OD, fitting type, thread, material, pressure rating, and quantity to sales@rrhydraulics.com for a certified offer.
2.1 — Push-In Fitting Size and Pressure Reference
| Tube OD (mm) | Compatible Tubing | Port Thread Options | Max Working Pressure | Min Burst Pressure | Temp Range | Application |
|---|---|---|---|---|---|---|
| 4 mm | PU, PA12, LDPE | M5, ⅛” BSP | 16 bar (232 psi) | ≥ 64 bar | −20 to +60°C | Miniature actuators; sensors; pilot circuits |
| 6 mm | PU, PA12, LDPE | ⅛”, ¼” BSP / NPT | 16 bar (232 psi) | ≥ 64 bar | −20 to +60°C | Standard instrument air; small cylinders |
| 8 mm | PU, PA12 | ¼”, ⅜” BSP / NPT | 16 bar (232 psi) | ≥ 64 bar | −20 to +60°C | Medium actuators; air preparation units |
| 10 mm | PU, PA12 | ¼”, ⅜” BSP / NPT | 16 bar (232 psi) | ≥ 64 bar | −20 to +60°C | Standard automation circuits; valve actuation |
| 12 mm | PA12, Semi-rigid | ⅜”, ½” BSP / NPT | 16 bar (232 psi) | ≥ 64 bar | −20 to +60°C | Large cylinders; high-flow circuits |
| 16 mm | PA12, Semi-rigid | ½”, ¾” BSP / NPT | 12 bar (174 psi) | ≥ 48 bar | −20 to +60°C | High-flow distribution; large actuators |
| ¼” OD | Nylon, copper | ⅛”, ¼” NPT | 16 bar (232 psi) | ≥ 64 bar | −20 to +60°C | US-coded systems; instrument air |
| ⅜” OD | Nylon, copper | ¼”, ⅜” NPT | 16 bar (232 psi) | ≥ 64 bar | −20 to +60°C | US process control; actuator supply |
2.2 — Thread Form Comparison Reference
| Thread | Standard | Angle | Taper | Seal Method | Sealant Required | Region / Application |
|---|---|---|---|---|---|---|
| NPT | ASME B1.20.1 | 60° | 1:16 (tapered) | Thread flanks | PTFE tape or anaerobic | USA; Americas; US-coded EPC |
| BSPT (R / Rc) | ISO 7-1 | 55° | 1:16 (tapered) | Thread flanks | PTFE tape or anaerobic | UK; Europe; Asia-Pacific; international EPC |
| BSPP (G) | ISO 228 | 55° | Parallel (no taper) | O-ring face seal | O-ring / bonded washer | European automation; ISO 4400 valve ports |
| Metric (M) ORFS | ISO 9974 | — | Parallel (metric) | O-ring face seal | O-ring | European hydraulic / pneumatic hybrids |
| JIC 37° | SAE J514 | 37° | Parallel + cone | Metal-to-metal cone | None (metal seal) | US hydraulic-to-pneumatic transitions |
2.3 — Applicable Standards and Compliance Framework
ISO 14743
Pneumatic fluid power — push-in connectors for thermoplastic tubing. Governs: tube OD dimensions and tolerances; fitting body port dimensions; collet design and retention requirements; minimum tube pull-out force at working pressure; pressure/temperature rating; and test methods. ISO 14743 push-in fittings are the international standard for industrial pneumatic automation systems. Working pressure rating per ISO 14743: 16 bar (232 psi) maximum for tube OD 4–12 mm at 20°C ambient temperature. Temperature de-rating: at 60°C, working pressure typically reduces to 12 bar; at −20°C, brittle failure risk of plastic collet components must be addressed by specifying stainless steel or metal collet variants.
ISO 8434-1 / ISO 8434-2
ISO 8434-1: Metallic tube connections for fluid power and general use — 24° cone fittings (DIN compression fittings, bite-type). ISO 8434-2: 37° flared tube fittings (JIC-type). These standards govern the heavy-duty compression fittings used in stainless steel instrumentation tubing (3/8″ and 1/2″ OD SS tubing at high pressure). While predominantly used in hydraulic and high-pressure instrument systems, ISO 8434-1 compression fittings are also specified in high-pressure pneumatic gas systems (nitrogen, instrument air above 16 bar) where push-in fitting pressure ratings are insufficient. Full metal-to-metal seal; no plastic or elastomeric sealing element; suitable for high-temperature applications above push-in fitting limits.
ISO 7-1 / ISO 228 / ASME B1.20.1
ISO 7-1: Pipe threads for joints with pressure-tight joints made on the threads (BSPT) — governing tapered pipe threads sealing on the flanks. ISO 228: Pipe threads for joints not making pressure-tight joints on the threads (BSPP / G-series parallel threads) — sealing on the face O-ring. ASME B1.20.1: Pipe Threads, General Purpose — NPT tapered thread. All three are referenced in pneumatic fitting specifications depending on project code and geographic region. The procurement document must explicitly state which thread standard applies — “1/4 inch pipe thread” is ambiguous; “1/4″ NPT per ASME B1.20.1” or “G1/4 BSPP per ISO 228” is unambiguous.
ISO 4414
Pneumatic fluid power — general rules and safety requirements for systems and their components. The overarching safety standard for pneumatic systems — covers fitting selection, installation, pressure testing, and maintenance. ISO 4414 requires that all pneumatic fittings be rated for the system working pressure with a minimum safety factor of 4:1 burst-to-working pressure ratio. It also requires that fittings be compatible with the fluid (air quality per ISO 8573-1) and the temperature range of the installation. For EPC pneumatic systems: ISO 4414 compliance is mandatory — this standard establishes the engineering basis for fitting pressure rating, safety factor, and system test procedure requirements.
ISO 8573-1
Compressed air — contaminants and purity classes. Defines compressed air quality classes for: particulate (solid particles), water (liquid, vapour, and pressure dew point), and oil (aerosol, vapour, and liquid) contamination. Purity class 1.4.1 (Class 1 particle, Class 4 water, Class 1 oil) is typical for clean instrument air systems. Pneumatic fitting material must be compatible with the compressed air quality — contaminated air (high moisture, high oil carryover) accelerates corrosion of brass fittings; low-lubrication air (Class 1 oil) may cause premature wear of collet and O-ring sealing surfaces in push-in fittings. Stainless steel and polymer fittings are preferred for moisture-laden or oil-free air systems.
ATEX Directive / IECEx
For pneumatic fittings installed in hazardous classified areas (ATEX Zone 1/2 or IECEx Zone 1/2) carrying flammable gases or in flammable gas-laden atmospheres: fittings must be made of materials that will not create sparks by impact or friction — brass (non-sparking) and stainless steel are acceptable; carbon steel fittings are not acceptable in Zone 1 gas atmospheres. Push-in fittings in ATEX areas: the plastic collet and body must be antistatic (surface resistance ≤ 10⁹ Ω) to prevent static charge accumulation that could create a spark. ATEX-rated fittings from certified manufacturers (Festo, SMC, Parker Watts) are the standard solution for Zone 1/2 pneumatic circuits in oil and gas facilities.
PED 2014/68/EU
Pressure Equipment Directive — for pneumatic fittings in European CE-marked pressure systems with working pressure above 0.5 bar and internal volume above 50 mL. Push-in and threaded fittings forming part of a CE-marked compressed air distribution system must comply with PED 2014/68/EU. Fittings below Category I (simple pressure vessels, low hazard) may be supplied with a Declaration of Conformity from the manufacturer; Category II and above require third-party notified body assessment. For EPC projects with European end destinations: verify PED category of the pneumatic system and ensure the fittings are PED-compliant with appropriate CE marking and Declaration of Conformity documentation.
ISO 6150 / ISO 6861
ISO 6150: Pneumatic fluid power — components using compressible fluids — determination of flow-rate characteristics. Provides the test method for determining Cv (flow coefficient) and critical pressure ratio for pneumatic fittings and components. ISO 6861: Pneumatic fluid power — components using compressible fluids — determination of the flow characteristics. Used by fitting manufacturers to establish and publish Cv tables that system designers use for pressure drop calculations in pneumatic circuit design. When specifying fittings for high-flow pneumatic circuits (large cylinder actuators, air-powered tools, high-volume blow-off systems): always request ISO 6150 Cv data from the fitting manufacturer for each fitting type and size before finalising the system design.
Sealing Systems
& Corrosive Environments
Pneumatic fitting material selection is driven by the compressed fluid composition, the process environment temperature, corrosion exposure, and any hazardous area or food-grade requirements. RR Hydraulic supplies pneumatic fittings in all standard grades — brass, nickel-plated brass, SS 316, and polymer — with full EN 10204 3.1 traceability on all metal fitting supply.
3.1 — Material Selection by Application Environment
| Material | Standard Air | Wet / Humid Air | Marine / Offshore | Chemicals | Food / Pharma | ATEX Zone 1/2 | Temp Max |
|---|---|---|---|---|---|---|---|
| Brass (CuZn) | Excellent | Good | Poor (dezinc.) | Poor (acids) | Not permitted | Yes (non-spark) | +150°C |
| Nickel-Plated Brass | Excellent | Very Good | Fair | Fair | Conditional | Yes | +150°C |
| SS 316 Body | Excellent | Excellent | Excellent | Very Good | Yes | Yes | +200°C |
| Nylon / Polyamide PA12 | Very Good | Good | Good | Fair | Yes (food-grade) | Antistatic grade | +80°C |
| PVDF (Kynar) | Good | Excellent | Excellent | Excellent | Yes | Check grade | +130°C |
| PEEK | Good | Excellent | Excellent | Excellent | Yes | Yes | +250°C |
3.2 — Sealing Systems and Elastomer Compatibility
NBR (Nitrile) O-Rings and Seals
The most common elastomeric sealing material in standard pneumatic push-in and threaded fittings — NBR (acrylonitrile-butadiene rubber) provides good resistance to petroleum-based lubricating oils present in lubricated compressed air systems (FRL — Filter/Regulator/Lubricator units). Service temperature: −40°C to +100°C. Poor resistance to: ozone, UV, ketones, esters, and aromatic hydrocarbons. For oil-free compressed air systems: NBR still acceptable (absence of oil does not degrade NBR). For instrument air: NBR standard. For nitrogen service: NBR acceptable. Not suitable for: compressed air used in oxygen-enriched environments (risk of NBR ignition in contact with oxygen-enriched air above 30% O₂).
FKM (Viton) O-Rings — Chemical / High-Temperature
Fluoroelastomer seals for elevated temperature and chemical-resistant pneumatic fittings. Service temperature: −20°C to +200°C (substantially higher than NBR). Excellent resistance to: petroleum oils, fuels, aromatic hydrocarbons, hydraulic fluid, and most acids. Used in: high-temperature compressed air systems (above 100°C, near heat sources); compressed natural gas (CNG) and other hydrocarbon gas systems; chemical plant compressed air in environments with acid or hydrocarbon vapours; and process industries where the compressed air may be contaminated with solvent vapours. Higher cost than NBR — specify FKM only where the temperature or chemical exposure justifies the premium; NBR is adequate for standard compressed air service.
EPDM O-Rings — Water and Steam
EPDM (ethylene-propylene-diene monomer) seals for water, steam, and ozone-exposed compressed air systems. Service temperature: −40°C to +150°C. Excellent resistance to: water, steam, dilute acids and alkalis, ozone, UV, and weathering. Poor resistance to: petroleum oils and fuels (swells in oil contact — EPDM cannot be used with lubricated compressed air). Used in: compressed air systems in water treatment and desalination plants (water carry-over in compressed air); food and beverage processing where water vapour-saturated air contacts fittings; outdoor compressed air systems exposed to UV and ozone. EPDM seals require oil-free compressed air — specify FRL oil-free compressors if EPDM fittings are used.
PTFE Seal Tape and Thread Sealant
PTFE (polytetrafluoroethylene) tape or PTFE-loaded anaerobic thread sealant for NPT and BSPT tapered threaded pneumatic connections. PTFE tape application: wrap clockwise direction (opposite to thread advancement direction) for 2–3 turns starting from the second thread; do not cover the first thread (the starter thread must remain clear for alignment). Anaerobic sealant (Loctite 565 — medium strength, designed for pneumatic applications) provides a more reliable seal than PTFE tape alone for high-cycle and vibration-prone connections. PTFE tape alone is inadequate for connections that will be repeatedly assembled and disassembled — the tape displaces progressively with each assembly cycle.
Bonded Seal Washers (Dowty Seals)
A bonded seal (Dowty seal) consists of a metal washer with a vulcanised elastomeric inner ring — the metal provides structural integrity and the rubber provides the pressure-tight seal against the flat face of the port or fitting. Used with BSPP (G-series parallel) pneumatic fittings where no O-ring groove is provided in the port face: the bonded seal goes between the fitting flat face and the port face, and the tightening torque compresses the rubber ring to create the seal. Bonded seals are available in standard and heavy-duty (high-pressure) versions. Elastomer: NBR standard; FKM for high-temperature or chemical service. Metal washer: steel (standard) or SS 316 for corrosive environments.
SS 316 Fittings for Offshore and Marine
Stainless steel SS 316 body push-in and threaded fittings for offshore platform instrument air systems, marine engine room pneumatic circuits, and coastal industrial compressed air distribution where brass fittings corrode in the marine atmospheric environment. SS 316 fitting bodies with EPDM or FKM O-rings (depending on the application fluid and temperature). Collet in stainless steel for SS push-in fittings — the standard plastic collet used in brass push-in fittings is not appropriate for offshore environments where UV, salt spray, and mechanical impact degrade the plastic collet over time. Passivation per ASTM A967 on all SS 316 pneumatic fitting lots. EN 10204 3.1 minimum for offshore pneumatic fitting supply.
3.3 — Tubing Compatibility and Selection
- Polyurethane (PU) tubing: The most common pneumatic tubing — excellent flexibility, abrasion resistance, and kink resistance; moderate pressure rating (rated to 10–12 bar at ambient temperature); suitable for most industrial automation applications; poor chemical resistance and UV stability — not suitable for outdoor or chemical environments
- Nylon PA12 tubing: Higher pressure rating than PU (rated to 15–16 bar at ambient); better chemical resistance and UV stability; stiffer than PU; the standard tubing for EPC instrument air systems, outdoor applications, and chemical plant pneumatic circuits; available in polyamide 11 (PA11) and polyamide 12 (PA12) — PA12 has lower moisture absorption and superior chemical resistance
- Polyethylene (PE / LDPE / HDPE): Soft, flexible, low-cost tubing; lower pressure rating (8–10 bar); poor abrasion resistance; suitable for light-duty air circuits in non-demanding environments; easy to cut and connect with push-in fittings; not suitable for elevated temperature or chemical exposure
- Semi-rigid Nylon (PA6 / PA66): Stiff, pressure-rated tubing for fixed compressed air distribution lines; rated to 20+ bar at ambient temperature; more difficult to route around obstacles but provides a cleaner, more professional installation than flexible tubing in permanent pneumatic circuits
- Copper tubing: Used with compression fittings for permanent, high-pressure, or high-temperature pneumatic circuits; excellent pressure rating and temperature capability; requires flaring or cutting tools for installation; does not connect with push-in fittings (too hard for collet grip)
- Stainless steel tubing: For high-pressure gas service, corrosive environments, and elevated-temperature pneumatic circuits; connects via ISO 8434-1 compression fittings; not compatible with push-in fittings; standard for offshore and chemical plant instrument air supply tubing
Industry Applications
& Documentation
RR Hydraulic maintains full traceability from certified bar and casting stock to final tested and packed pneumatic fitting shipment. Dimensional inspection, hydrostatic pressure testing, thread gauging, material certification, and complete EPC and industrial export documentation packages are standard on all project-grade pneumatic fitting supply.
4.1 — Inspection & QC Protocol
4.2 — EN 10204 Material Test Certificate Requirements
| Certificate | Content | EPC Requirement | When Mandatory |
|---|---|---|---|
| 2.1 / 2.2 | Declaration / non-specific | General commercial hardware | Acceptable for non-critical general industry pneumatic circuits |
| 3.1 | Bar/casting heat-traceable mech + chem | Standard for EPC instrument air and control | All SS 316, DZR brass offshore, and EPC pneumatic fitting supply |
| 3.2 | 3.1 + TPI countersign | Offshore safety-critical; nuclear; ATEX Zone 1 | Offshore safety-system pneumatic supply; nuclear; ATEX Zone 1 |
4.3 — Applications by Industry
EPC Instrument Air and Control Valve Actuation
PA12 nylon tubing with nickel-plated brass or SS 316 push-in fittings (6–10 mm OD, ⅛”–¼” BSP port) for instrument air supply to control valve pneumatic positioners, solenoid valve pilot signals, and pneumatic actuator supply on EPC process plant. The critical design requirement is zero leakage — a leaking instrument air connection to a critical control valve creates a sustained spurious signal that moves the valve without a process command. All instrument air pneumatic fittings must be pressure tested and verified leak-free (bubble test at 1.5× working pressure) before commissioning. EN 10204 3.1 on all SS 316 and metal fitting lots; full traceability from the raw material to the installed fitting lot number.
Offshore Platform Pneumatic Circuits
SS 316 push-in and threaded fittings with FKM O-rings for offshore platform compressed air and instrument air distribution — the combination of SS body (marine corrosion resistance), SS collet (mechanical durability in outdoor UV and salt spray), and FKM seals (temperature and chemical resistance) provides the longest service life in offshore environments. Antistatic nylon PA12 tubing for ATEX Zone 2 classified areas. ATEX-rated push-in fittings with antistatic body for Zone 1 instrument air in gas-risk areas. DNV-OS-D101 (marine systems) compliance for offshore platform instrument air system fittings on classed vessels and platforms. EN 10204 3.1 with lot traceability; pressure test certificates per lot.
Food and Pharmaceutical Grade Pneumatic Systems
FDA 21 CFR-compliant nylon PA12 or PVDF push-in fittings with EPDM O-rings for compressed air circuits in food processing, beverage production, and pharmaceutical manufacturing environments. All food-contact surfaces must be smooth, crevice-free, and compatible with CIP (clean-in-place) caustic and acid cleaning cycles — PVDF push-in fittings and tubing provide excellent chemical resistance to CIP agents. EPDM seals for wet or steam-cleaned environments (NBR is not suitable for steam). FDA compliance declaration per 21 CFR Part 177 for polymer fittings; no copper or brass fittings permitted in direct food contact applications (copper inhibits bacterial growth in water systems but must be reviewed for specific food chemistry). EN 10204 3.1 on SS 316 fittings.
Industrial Automation and Robotics
High-cycle push-in fittings (PU tubing, brass or nickel-brass body, NBR O-rings) for robotic cell pneumatic circuits — pick-and-place, welding fixture clamping, press-loading tooling, and conveyor divert gates. The push-in collet and O-ring system is rated for millions of insertion/removal cycles when using quality PA12 or PU tubing within the manufacturer’s tube OD tolerance range. Use only tubing within the manufacturer’s specified OD tolerance (typically ±0.1 mm) — oversize tubing (outside tolerance) prevents collet release; undersize tubing does not engage the collet sufficiently for rated pull-out resistance. Always clean tube ends before insertion — contaminated or damaged tube ends cause collet damage and premature seal wear.
Nitrogen Purge and Inert Gas Systems
SS 316 compression fittings (ISO 8434-1) or high-quality push-in SS 316 fittings for nitrogen purge systems in oil and gas facility electrical panels, analyser shelters, and ATEX equipment enclosures. Nitrogen is non-toxic and non-flammable but displaces oxygen — any leak in a confined nitrogen purge system creates an asphyxiation hazard. All nitrogen purge pneumatic fittings must be pressure tested and proven leak-free before commissioning. The nitrogen purge system design and commissioning must comply with IEC 60079-2 (Ex p — pressurised and purged enclosures) for ATEX certification purposes. SS 316 fittings preferred for nitrogen service to avoid brass dezincification in the presence of any condensate.
Process Analyser Sample Conditioning Systems
SS 316 Swagelok-type compression fittings (ISO 8434-1, ⅛” and ¼” OD SS tubing) for the pneumatic carrier gas and purge connections in process gas chromatograph (GC) and analyser sample conditioning systems — where contamination of the sample stream from fitting corrosion products or O-ring degradation would cause false analyser readings. SS 316 compression fittings with stainless ferrules provide a completely metal-to-metal seal path with zero polymer or elastomeric contamination of the sample gas. Carrier gas circuits in GC and analyser systems are also at elevated pressure (helium or hydrogen carrier at 4–8 bar) and require the higher pressure rating of compression fittings vs push-in fittings. EN 10204 3.1 mandatory for all SS fitting supply to process analyser systems.
4.4 — Export Packaging Specification
- Pneumatic fittings packed by type, tube OD, thread form, material, and fitting orientation (straight, elbow, tee, reducing) in individually labelled polybag or plastic box — mixing fitting types (e.g., straight unions with elbows) creates field sorting time; individual type-and-size packaging eliminates this waste on large pneumatic installation projects
- Push-in fittings: collet release button protected with transit cap or plug in tube bore entry — the collet teeth are pre-stressed and can be damaged by transit impacts if the tube bore is open; plastic transit plugs maintain the collet in the release-neutral position during shipping
- Threaded fittings: thread ports protected with plastic thread caps matching the port thread — protects both the thread form and the O-ring groove (where applicable) from transit damage; thread caps colour-coded for easy identification (BSPT caps in one colour; BSPP/G caps in another)
- SS 316 pneumatic fittings in dedicated SS-labelled packaging, segregated from brass and nickel-brass; iron contamination from CS or brass tooling/handling on passivated SS surfaces causes corrosion in offshore and marine service — all packaging hardware for SS fittings must be SS or plastic
- EPC project bulk supply: fittings packed per instrument air loop drawing line item — each package labelled with the P&ID reference, instrument loop number, and fitting type per the pneumatic installation list; matching the package to the installation drawing eliminates part sorting on site
- Documentation in waterproof pocket: EN 10204 3.1/3.2 MTC, pressure test certificate per lot, thread gauge report (100%), pull-out test certificate (push-in), PMI report (SS/DZR brass), DZR test (marine brass), O-ring elastomer type confirmation, passivation certificate (SS), and FAI report
- ISPM-15 crates or export cartons for international shipment; desiccant sachets for ocean freight to tropical destinations; individual lots clearly marked with lot number cross-referenced to all QC certificates
4.5 — Complete Project Documentation Package
| # | Document | Standard / Format | Mandatory / Conditional | Notes |
|---|---|---|---|---|
| 01 | Material Test Certificate (MTC) | EN 10204 3.1 / 3.2 | Mandatory — SS; DZR brass offshore; EPC | Bar/casting heat-traceable; one MTC per heat lot |
| 02 | Chemical Composition Report | Certified lab analysis | Mandatory — SS 316; DZR brass | Cu%, Ni%, Mo%, Pb% limits per material spec |
| 03 | Hydrostatic Pressure Test Certificate | ISO 14743 / ISO 4414 — 4× WP | Mandatory — all pneumatic fittings | Test pressure, hold time, pass/fail per lot |
| 04 | Pneumatic Leak Test Certificate | Air test at 1.5× WP submerged | Mandatory — EPC instrument air supply | Zero bubble at 1.5× WP; per lot sample |
| 05 | Thread Gauge Report | NPT L1 / BSPT L1 / BSPP 6H gauges | Mandatory — 100% all threaded fittings | Correct thread form and taper verified; calibrated gauges |
| 06 | Tube Pull-Out Force Certificate | ISO 14743 pull-out test per OD size | Mandatory — all push-in fittings | Minimum pull-out force at working pressure per lot |
| 07 | Dimensional Inspection Report | Per manufacturer drawing / ISO 14743 | Mandatory | Tube bore, thread port, overall dimensions |
| 08 | PMI Report (XRF) | Per lot — SS / PVDF / DZR brass | Mandatory — SS 316 and DZR brass lots | SS 316 vs SS 304; DZR brass Cu% and As/Sn addition |
| 09 | DZR Test Certificate | ISO 6509 / BS 2874 | Conditional — marine; hot water; potable water | Dezincification depth ≤ 200 µm acceptance |
| 10 | O-Ring Elastomer Confirmation | Lot material declaration per compound | Mandatory — all fittings with elastomeric seals | NBR / FKM / EPDM confirmed per lot; Shore hardness |
| 11 | Passivation Certificate | ASTM A967 | Mandatory — all SS 316 fittings | Cu-sulphate or water immersion acceptance test |
| 12 | ATEX / IECEx Certificate | EN 60079-0 / IEC 60079-0 | Conditional — ATEX Zone 1/2 installation | Certified fittings with zone, gas group, temp class |
| 13 | First Article Inspection (FAI) Report | Project-specific format | Mandatory — new project configurations | All parameters including pressure test; before batch production |
| 14 | TPI Witness Certificate | SGS / BV / DNV / Lloyds | Conditional — EN 10204 3.2; offshore; nuclear | Witnesses pressure test + dimensional + thread gauge |
| 15 | ISO 9001:2015 Certificate | Third-party QMS certification | Mandatory — EPC projects | Scope covers pneumatic fitting manufacture and test |
| 16 | Country of Origin + Packing List | Chamber of Commerce / item-level | Mandatory | HS tariff code; thread form on packing list |
| 17 | Commercial Invoice + Bill of Lading | Per INCOTERMS 2020 | Mandatory | Freight forwarder issued |
4.6 — ISO and Quality System Compliance
ISO 9001:2015
Quality Management System covering bar and casting stock procurement and heat traceability, machining process qualification (thread cutting per NPT/BSPT/BSPP standards, collet seat bore tolerance, tube bore tolerance), hydrostatic pressure test procedure qualification (calibrated test equipment, test pressure, hold time records), tube pull-out test procedure qualification (calibrated force gauge, test rate, acceptance criteria), thread gauge protocol (100% Go/No-Go, gauge calibration per ISO 10012), O-ring installation inspection protocol, passivation process control, PMI procedure, and full material traceability. Mandatory for all EPC, offshore, and process control pneumatic fitting procurement qualification.
ISO 14743 / ISO 4414
ISO 14743 (push-in connectors for thermoplastic tubing) and ISO 4414 (general safety requirements for pneumatic systems) together constitute the complete specification and safety framework for push-in pneumatic fitting systems. ISO 14743 defines the fitting performance requirements; ISO 4414 defines the system-level safety requirements within which the fitting operates. For EPC pneumatic system specifications: reference both standards — ISO 14743 for fitting performance and pressure rating; ISO 4414 for system safety and pressure test requirements. A fitting that meets ISO 14743 performance requirements but is installed in a system that violates ISO 4414 safety requirements is still a safety non-conformance.
IEC 60079 / EN 60079 (ATEX)
IEC 60079-0: Explosive atmospheres — general requirements. IEC 60079-2: Equipment protection by pressurised enclosures (Ex p). IEC 60079-14: Explosive atmospheres — electrical installations design, selection and erection. Pneumatic fittings in ATEX Zone 1 (continuous explosive atmosphere hazard) and Zone 2 (occasional explosive atmosphere) must comply with the relevant IEC 60079 protection concept. For intrinsically pneumatic circuits carrying flammable gas in Zone 1: specify ATEX-certified fittings with zone, equipment group (IIA/IIB/IIC) and temperature class (T1–T6) marking. For instrument air circuits in Zone 2: antistatic polymer fittings per IEC 60079-0 surface resistance requirements (≤ 10⁹ Ω) are typically acceptable without individual ATEX certification.
ISO 8573 / ISA 7.0.01
ISO 8573-1 (Compressed air — contaminants and purity classes) and ISA 7.0.01 (US instrument air quality standard) define the compressed air quality requirements that directly affect pneumatic fitting material selection, seal compatibility, and service life. ISO 8573-1 Class 1.4.1 (instrument air quality): ≤ 0.1 µm particles; pressure dew point ≤ −20°C; oil content ≤ 0.01 mg/m³. All pneumatic fittings in instrument air service must be compatible with this air quality specification — NBR seals are adequate for ISO 8573-1 Class 1.4.1; dry nitrogen (zero moisture, zero oil) requires EPDM or PTFE seals in some temperature ranges where NBR stiffens and loses sealing force at sub-zero dew points.
Submit your tube OD, fitting type, thread form, material, O-ring elastomer, and quantity to RR Hydraulic for a complete, certified commercial offer.