Titanium Gr 4 Weld Neck Flanges | Titanium Gr 4 Blind Flanges | Titanium Gr 4 Slip On Flanges | Titanium Gr 4 Socket Weld Flanges | Titanium Gr 4 Threaded Flanges | ASTM B381 Grade 4 Flanges | UNS R50700 Flanges | ASME B16.5 Titanium Flanges | DIN 3.7065 Flanges
Titanium Grade 4 flanges (UNS R50700, ASTM B381 / ASME SB-381) are manufactured from the highest-strength commercially pure (CP) titanium available. Among the four CP titanium grades, Grade 4 achieves the greatest tensile strength — a minimum of 550 MPa (80 ksi) — by incorporating the highest allowable oxygen content (0.40% max), which acts as an interstitial strengthener in the titanium lattice without compromising the outstanding corrosion resistance that defines all CP titanium grades.
Tesco Steel & Engineering manufactures Titanium Grade 4 flanges in India across all standard flange types per ASME B16.5, ASME B16.47, EN 1092-1, and other international standards. We supply to refineries, desalination plants, chemical processing facilities, marine platforms, and pharmaceutical plants across 96 countries on six continents. All flanges are supplied with EN 10204 3.1 material test certificates and full dimensional inspection reports.
Titanium Grade 4 is an unalloyed (commercially pure) titanium defined by ASTM B381 / ASME SB-381. It is designated UNS R50700 and identified by the DIN designation 3.7065. "Commercially pure" means titanium of high purity with only trace interstitial elements — oxygen, nitrogen, carbon, hydrogen, and iron — that are controlled to specific limits.
The four CP titanium grades are defined primarily by their oxygen and iron content, which govern strength:
| Grade | UNS | Oxygen Max (%) | Iron Max (%) | UTS Min (MPa) | Yield Min (MPa) |
|---|---|---|---|---|---|
| Grade 1 | R50250 | 0.18 | 0.20 | 240 | 170 |
| Grade 2 | R50400 | 0.25 | 0.30 | 345 | 275 |
| Grade 3 | R50550 | 0.35 | 0.30 | 450 | 380 |
| Grade 4 | R50700 | 0.40 | 0.50 | 550 | 483 |
| Grade 5 (alloy) | R56400 | 0.20 | 0.30 | 895 | 828 |
Note: Grade 5 (Ti-6Al-4V) is a titanium alloy, not a CP grade. It has higher strength but lower corrosion resistance and harder weldability than Grades 1–4.
| Element | Maximum Limit (%) | Role / Significance |
|---|---|---|
| Oxygen (O) | 0.40 | Primary strengthening interstitial; highest limit of all CP grades — responsible for Grade 4's superior strength |
| Iron (Fe) | 0.50 | Secondary strengthener; higher than Grades 1–3 |
| Carbon (C) | 0.10 | Carbide formation if excessive; kept low to maintain ductility |
| Nitrogen (N) | 0.05 | Increases strength but reduces ductility and toughness; strictly limited |
| Hydrogen (H) | 0.015 (forgings) / 0.0125 (sheet) | Causes hydrogen embrittlement if too high; lowest-limit element |
| Titanium (Ti) | Balance (≥ 99.0%) | Base metal |
| Property | Value (ASTM B381 — Forgings, Annealed) |
|---|---|
| Tensile Strength (UTS) — Minimum | 550 MPa (80 ksi) |
| Yield Strength (0.2% Offset) — Minimum | 483 MPa (70 ksi) |
| Elongation in 4D gauge — Minimum | 15% |
| Reduction in Area — Minimum | 25% |
| Hardness (typical) | 200–280 HB |
| Density | 4.51 g/cm³ |
| Elastic Modulus | 105–110 GPa |
| Thermal Conductivity at 20°C | ~15 W/m·K |
| Coefficient of Thermal Expansion (20–300°C) | 8.6 × 10⁻⁶ /°C |
| Max. Continuous Service Temperature | ~315°C (CP titanium begins oxidising above 540°C) |
Tesco Steel & Engineering manufactures all standard flange configurations in Titanium Grade 4 per ASME B16.5, ASME B16.47, and EN 1092-1:
| Flange Type | Short Code | Standard | Typical Application |
|---|---|---|---|
| Weld Neck | WNRF | ASME B16.5 / B16.47 | High-pressure, high-cycle fatigue service; preferred for critical titanium piping |
| Slip On | SORF | ASME B16.5 | Low-to-moderate pressure; easier fit-up than weld neck |
| Blind | BL | ASME B16.5 / B16.47 | Closing pipe ends; inspection access in corrosive service |
| Socket Weld | SWRF | ASME B16.5 | Small-bore (½″–2½″) high-pressure chemical lines |
| Threaded / Screwed | TH | ASME B16.5 | Low-pressure non-shock, non-vibration; instrument connections |
| Lapped Joint (Loose) | LJ | ASME B16.5 | Systems requiring frequent dismantling; used with titanium stub ends |
| Long Weld Neck | LWN | ASME B16.36 / API | Nozzle connections on pressure vessels; heat exchanger channels |
| Spectacle Blind | SB | ASME B16.48 | Positive isolation of corrosive process lines for maintenance |
| Orifice Flanges | ORF | ASME B16.36 | Flow measurement in corrosive fluid systems |
| Ring Type Joint | RTJ | ASME B16.5 | High-pressure, high-temperature service requiring metal-to-metal seal |
| Plate / Flat Flanges | PL / FF | Customer drawing | Equipment connections, low-pressure tanks, custom assemblies |
Selecting the right titanium grade for flanges involves balancing strength, corrosion resistance, weldability, and cost. This comparison covers the three most commonly specified titanium flange grades:
| Property | Grade 2 (UNS R50400) | Grade 4 (UNS R50700) | Grade 5 (UNS R56400 / Ti-6Al-4V) |
|---|---|---|---|
| Type | Commercially Pure (CP) | Commercially Pure (CP) | Alpha-Beta Alloy |
| ASTM Standard | B381 / SB-381 | B381 / SB-381 | B381 / SB-381 |
| UTS Minimum | 345 MPa (50 ksi) | 550 MPa (80 ksi) | 895 MPa (130 ksi) |
| Yield Minimum | 275 MPa (40 ksi) | 483 MPa (70 ksi) | 828 MPa (120 ksi) |
| Corrosion Resistance | Excellent (all CP grades) | Excellent (equal to Gr 2) | Good (inferior to CP grades in reducing acids) |
| Weldability | Excellent | Very Good | Moderate (requires PWHT) |
| Ductility / Formability | Highest among CP grades | Good | Lower (less formable) |
| Relative Cost | Baseline | ~15–20% premium over Gr 2 | ~50–80% premium over Gr 2 |
| Best For | General corrosive service; highest ductility; most economical | Higher-pressure corrosive service; max CP strength without alloy | High-strength structural; aerospace; maximum pressure ratings |
Recommendation: Use Grade 4 flanges when Grade 2's ASME B16.5 pressure-temperature ratings are insufficient and Grade 5's welding challenges are undesirable. Grade 4 is the ideal middle ground — CP corrosion resistance at near-alloy strength.
Titanium Grade 4 forms a stable, adherent, and self-repairing titanium dioxide (TiO₂) passive oxide film on its surface when exposed to oxygen or moisture. This film provides exceptional corrosion resistance across a wide range of environments — performance that no stainless steel grade can match in many applications.
| Industry | Application | Why Titanium Grade 4? |
|---|---|---|
| Chemical Processing | Wet chlorine gas lines, sodium hypochlorite plants, bleach storage, nitric acid reactors | Exceptional resistance to oxidising environments where SS 316L fails due to pitting; higher strength than Gr 2 for elevated-pressure reactors |
| Desalination | MSF evaporator flanges, RO membrane housings, brine heater connections | Outstanding seawater resistance with zero corrosion allowance; lightweight reduces structural load on offshore platforms |
| Marine & Offshore | Seawater cooling systems, subsea pipeline flanges, offshore platform piping | Immune to seawater corrosion; Gr 4 strength suits higher-pressure offshore lines vs Gr 2 |
| Oil & Gas | Sour gas injection lines, chloride-containing produced water systems | Resists chloride SCC that causes SS 316L failure; higher strength than Gr 2 for deepwater pressure ratings |
| Power Generation | Condenser water boxes, FGD (flue gas desulphurisation) absorber flanges | Resists chloride-laden cooling water; FGD slurry corrosion resistance superior to duplex stainless in some conditions |
| Pharmaceutical & Food | Reactor vessel nozzles, clean-in-place piping, product contact flanges | Biocompatibility and non-toxicity; surface oxide layer is inert to food-grade acids; meets FDA requirements |
| Aerospace | Hydraulic system flanges, fuel system connections, structural firewall fittings | CP titanium used where alloy grades are over-specified; Grade 4 provides additional strength margin vs Gr 2 in structural fittings |
| Pulp & Paper | Bleach plant piping flanges, chlorine dioxide contact equipment | Only material reliably resistant to hot ClO₂ and combined chlorine species at process temperatures |
Titanium Grade 4 is readily weldable by Gas Tungsten Arc Welding (GTAW / TIG). Because titanium reacts aggressively with oxygen and nitrogen above approximately 400°C, all welding must be performed with strict atmospheric protection:
| Welding Parameter | Requirement for Titanium Grade 4 |
|---|---|
| Welding Process | GTAW (TIG) — preferred; GMAW (MIG) possible with care; plasma arc welding for automated production |
| Shielding Gas | Argon or helium (99.995% purity minimum) on cover pass and root pass |
| Trailing Shield | Mandatory — protects cooling weld metal and HAZ behind the torch down to below 400°C |
| Root (Back) Purge | Full argon purge of weld root interior until oxygen level <50 ppm (measured by oxygen analyser) |
| Filler Metal | AWS A5.16 ERTi-4 (Grade 4 filler wire) or ERTi-2 (Grade 2 filler for lower-strength joints) |
| Weld Colour Acceptance | Silver (bright) = fully protected (acceptable); Straw / gold = light contamination (accept with caution); Blue = contaminated (reject); Grey / white = heavily contaminated (reject) |
| Post-Weld Heat Treatment | Not mandatory; stress relief at 480–595°C in vacuum or inert atmosphere recommended for heavily restrained joints |
| Preheat | Not required; welding at ambient temperature |
| Standard | Scope |
|---|---|
| ASTM B381 / ASME SB-381 | Titanium and titanium alloy forgings — primary material specification for Grade 4 flanges |
| ASME B16.5 | Pipe flanges and flanged fittings — NPS ½ to 24, Classes 150# to 2500# (Group 3.1 — titanium P-T ratings) |
| ASME B16.47 | Large diameter steel flanges — NPS 26 to 60 (Series A: MSS SP-44; Series B: API 605) |
| ASME B16.36 | Orifice flanges — NPS 1 to 16 |
| ASME B16.48 | Line blanks — spectacle blinds and paddle blanks |
| EN 1092-1 | European flange standard — PN rated system (PN 6 to PN 400) |
| DIN 2527 / DIN 2631 to 2638 | German DIN flanges — metric PN ratings; titanium DIN 3.7065 |
| JIS B2220 | Japanese Industrial Standard steel pipe flanges — applicable to titanium grades |
| ASTM B265 | Titanium strip, sheet and plate — Grade 4 (used for plate flanges) |
| ASME Section IX | Welding and brazing qualifications — procedure qualification for titanium welding |
| AWS A5.16 | Specification for titanium and titanium alloy welding electrodes and rods (ERTi-4) |
| EN 10204 3.1 / 3.2 | Material test certificates — 3.1 supplied standard; 3.2 third-party on request |
| Titanium Grade 4 Flanges — Available Specifications | |
|---|---|
| Material Grade | Titanium Grade 4, UNS R50700, DIN 3.7065 |
| Material Standard | ASTM B381 / ASME SB-381 Grade F-4 |
| Size Range | ½″ NB to 56″ NB (DN 15 to DN 1400) |
| Pressure Class (ASME) | 150#, 300#, 600#, 900#, 1500#, 2500# |
| Pressure Rating (PN) | PN 6, PN 10, PN 16, PN 25, PN 40, PN 64, PN 100, PN 160, PN 250, PN 320, PN 400 |
| Schedule / Wall Thickness | STD, XS, XXS, Sch 10, 20, 40, 80, 120, 160 |
| Flange Types | Weld Neck (WNRF), Slip On (SORF), Blind (BL), Socket Weld (SWRF), Threaded (TH), Lapped Joint (LJ), Long Weld Neck (LWN), Spectacle Blind (SB), Orifice, RTJ, Plate, Flat |
| Flange Face | Raised Face (RF), Flat Face (FF), Ring Type Joint (RTJ), Male-Female (MF), Tongue & Groove (T&G) |
| Facing Finish | 125–250 AARH stock finish (per ASME B16.5); smooth finish for PTFE gaskets; RTJ grooves per ASME B16.20 |
| Dimensional Standards | ASME B16.5, ASME B16.47 (Series A & B), EN 1092-1, DIN, JIS B2220, AWWA, AS 2129 |
| Additional Services | Third-party inspection (TPIA), PMI (Portable Metal Identification), Hydrostatic testing, Radiography (RT), Ultrasonic testing (UT), Pickling & passivation, Anodising, Custom marking (heat number, grade, size, pressure class per MSS SP-25) |
Every Grade 4 titanium flange leaves our facility with full documentation — heat number traceability from mill MTC to final inspection report and packing list.
Titanium machining requires dedicated tooling and environments free from cross-contamination with ferrous metals. Our titanium production is kept segregated from steel machining areas.
We supply Titanium Grade 4 flanges to refineries, chemical plants, desalination plants, and marine platforms across the Middle East, Europe, Southeast Asia, Africa, and the Americas.
We manufacture Grade 4 titanium flanges to customer-supplied P&ID requirements, piping specifications, or dimensional drawings — any type, any size.
Material Test Certificates per EN 10204 3.1 are standard. Third-party witnessed 3.2 certificates are available with your nominated inspection authority (Bureau Veritas, Lloyd's, SGS, DNV, etc.).
Standard Grade 4 titanium flange sizes are maintained in stock for rapid despatch. Custom sizes manufactured on priority with competitive lead times.
Titanium Grade 4 (UNS R50700, ASTM B381 Grade F-4, DIN 3.7065) is the highest-strength commercially pure (CP) titanium. It is unalloyed titanium with controlled interstitial elements — maximum 0.40% oxygen, 0.50% iron, 0.10% carbon, 0.05% nitrogen, and 0.015% hydrogen. The elevated oxygen content relative to Grades 1–3 acts as an interstitial strengthener, raising the minimum tensile strength to 550 MPa (80 ksi) while maintaining the full corrosion resistance of all CP titanium grades.
Titanium Grade 4 has the UNS designation R50700. The governing ASTM standard for Grade 4 forgings (including flanges) is ASTM B381 Grade 4 / ASME SB-381. The AMS aerospace specification is AMS 4921, and the DIN designation is 3.7065.
The key difference is mechanical strength. Titanium Grade 2 (UNS R50400) has a minimum tensile strength of 345 MPa (50 ksi) and is the most commonly used CP titanium grade. Grade 4 (UNS R50700) has a minimum tensile strength of 550 MPa (80 ksi) — approximately 60% higher. Both grades have identical corrosion resistance. Grade 4 is specified when the ASME B16.5 pressure-temperature ratings achieved with Grade 2 material are insufficient and the design requires more structural capability without switching to Grade 5 (Ti-6Al-4V alloy), which has welding challenges.
Per ASTM B381 (forgings, annealed condition): Tensile Strength minimum 550 MPa (80 ksi); Yield Strength (0.2% offset) minimum 483 MPa (70 ksi); Elongation minimum 15%; Reduction in Area minimum 25%. Typical hardness is 200–280 HB. Density is 4.51 g/cm³ and elastic modulus is approximately 105–110 GPa.
The primary material standard is ASTM B381 / ASME SB-381 (titanium forgings). Flange dimensions and pressure-temperature ratings are governed by ASME B16.5 (NPS ½–24, Class 150–2500) — titanium falls under Material Group 3.1 with its own P-T rating table. Large diameter flanges use ASME B16.47. European flanges follow EN 1092-1. The welding filler material standard is AWS A5.16 ERTi-4.
Grade 4 is chosen when Grade 2's corrosion resistance is needed but its strength (345 MPa) is insufficient. Key applications: chemical plants handling wet chlorine, sodium hypochlorite, and nitric acid; desalination plants (MSF and RO); offshore seawater cooling systems; pulp and paper bleach plants; pharmaceutical and food processing reactors; aerospace structural fittings where CP titanium is preferred over alloys; and power plant FGD absorber systems.
Yes. Titanium Grade 4 is readily welded by GTAW (TIG). However, titanium reacts with oxygen and nitrogen above ~400°C, causing contamination and embrittlement. All welding must be performed with: argon or helium shielding (99.995% minimum purity), trailing shields, full root purge to less than 50 ppm O₂, and ERTi-4 filler wire. Weld quality is judged by colour — a silver/bright weld is fully protected; blue or grey indicates contamination and must be rejected. Post-weld heat treatment is not mandatory for Grade 4.
Titanium Grade 4 has outstanding corrosion resistance due to its self-repairing TiO₂ passive oxide film. It resists seawater, wet chlorine gas, sodium hypochlorite, nitric acid (all concentrations), most organic acids, and dilute mineral acids. It is immune to chloride pitting and stress corrosion cracking that attack austenitic and duplex stainless steels. Limitations: attacked by dry chlorine at elevated temperatures, concentrated hot HCl and H₂SO₄, and HF acid in any concentration.
ASME B16.5 Group 3.1 (titanium) pressure-temperature ratings extend to approximately 316°C (600°F) for commercially pure titanium grades including Grade 4. Above this temperature, titanium begins to oxidise at an accelerating rate. For continuous service, most engineers limit CP titanium to around 260–315°C. In vacuum or inert atmosphere, titanium can be used at higher temperatures, but this is not applicable to standard piping flanges.
Titanium Grade 4 flanges are significantly more expensive than stainless steel or duplex flanges — typically 5–10× the cost of SS 316L flanges of comparable size and pressure class. However, the cost comparison must be made on a total-cost-of-ownership basis: titanium flanges have zero corrosion allowance (because they do not corrode in service), providing much longer service life in aggressive environments. In chlorine, bleach, and seawater service, titanium flanges can be cost-competitive with SS 316L or duplex flanges that require frequent replacement. Contact Tesco Steel for a project-specific price quotation.
Titanium Grade 4 Flanges — Manufacturer / Supplier / Stockist in: Kuwait, UAE, Germany, Saudi Arabia, West Africa, Iraq, Congo, Mexico, Bahrain, Canada, Philippines, Thailand, Kenya, Oman, Malaysia, Turkey, Qatar, Sudan, Netherlands, Nigeria, Lithuania, Gabon, Russia, Vietnam, Angola, Bolivia, Indonesia, UK, Yemen, Italy, United States, Venezuela, Spain, Iran, Estonia, Kazakhstan, Algeria, Jordan, Ecuador, Portugal, Colombia, Libya, Chile, Peru, South Africa, Namibia, Afghanistan, Israel, Zambia, Morocco, Denmark, Taiwan, Norway, Belarus, North Macedonia, Lebanon, Sri Lanka, Bhutan, Bulgaria, Ukraine, Belgium, Finland, Slovakia, Romania, France, Brazil, Trinidad & Tobago, Fiji, Tunisia, Gambia, Hungary, Zimbabwe, Mongolia, Ghana, Egypt, Czech Republic, Azerbaijan, Poland, Greece, Costa Rica, New Zealand, Croatia, Puerto Rico, Tanzania, Somalia, Singapore, Australia, Japan, South Korea, Bangladesh.
Major Exporting Cities: Dubai, Abu Dhabi, Sharjah, Riyadh, Jeddah, Al Jubail, Al Khobar, Dammam, Kuwait City, Manama, Doha, Muscat, Tehran, Ahvaz, Lagos, Nairobi, Johannesburg, Moscow, Atyrau, Istanbul, London, Houston, Los Angeles, New York, Dallas, Toronto, Calgary, Montreal, Singapore, Kuala Lumpur, Bangkok, Jakarta, Ho Chi Minh City, Hanoi, Seoul, Busan, Tokyo, Sydney, Melbourne, Perth, Cairo, Casablanca, Algiers, Karachi, Mumbai, Chennai, Pune, Vadodara, Colombo.
