Titanium Grade 2 Flanges

Titanium Grade 2 (F-2, UNS R50400) Flanges to ASTM B381 and ASME B16.5

Dinesh Tube India supplies and exports titanium Grade 2 flanges from Mumbai for seawater, chlor-alkali, refinery, power and chemical piping in India and abroad. Grade 2 flanges are machined from forgings to ASTM B381 / ASME SB381 Grade F-2 (UNS R50400, Werkstoff 3.7035), with dimensions to ASME B16.5, and are supplied with EN 10204 3.1 mill test certificates.

Grade 2 is commercially pure titanium and the most widely used titanium flange grade. It resists seawater, wet chlorine and most chloride service at the lowest cost of the titanium grades, and matches Grade 2 pipe and Grade 2 fittings. For all grades, see our titanium flanges page.

Table of Contents

Grade 2 Flange Types
Specification & Sizes
Lap-Joint Option
F-2 vs F-12 vs F-7
Chemical Composition
Mechanical Properties
Applications
FAQs

Titanium Grade 2 F-2 flanges to ASTM B381

Titanium Grade 2 Flange Types

Weld Neck Flange

Butt-welded to the pipe; the best choice for higher pressure and cyclic service.

Slip-On Flange

Slides over the pipe and is fillet-welded; for lower-pressure lines.

Blind Flange

Closes pipe ends, nozzles and vessel openings.

Socket Weld Flange

For small-bore lines, usually 2" NPS and below.

Threaded Flange

For small-bore, low-pressure lines where welding is not possible.

Lap Joint & RTJ

Lap-joint flanges with stub ends, and ring-type-joint faces on request.

Lap-Joint Option: Grade 2 Stub End with Backing Flange

A solid Grade 2 flange is not always needed. In a lap-joint assembly, only the stub end touches the process fluid, so it is made in Grade 2 while the loose backing flange can be carbon steel, coated steel or stainless steel. This is the usual low-cost way to flange titanium piping, and the loose flange also makes bolt-hole alignment easier.

Stub end: Grade 2 (WPT2) to ASTM B363, long or short pattern. See Grade 2 pipe fittings.
Backing flange: lap-joint flange to ASME B16.5 in a cheaper material.
When to use solid F-2: where the flange face or bore is wetted, for blind flanges, or where the specification requires it.

F-2 vs F-12 vs F-7 Flanges

Point	F-2 (Grade 2)	F-12 (Grade 12)	F-7 (Grade 7)
Min. tensile / yield	345 / 275 MPa	483 / 345 MPa	345 / 275 MPa
Seawater, wet chlorine	Excellent	Excellent	Excellent
Crevice corrosion under gaskets in hot brines	Fair	Excellent	Excellent
Dilute reducing acids	Poor to fair	Good	Best
Cost and availability	Lowest; widest range	Moderate	Highest; mostly to order

Titanium Grade 2 Flange Chemical Composition (ASTM B381 F-2, %)

Element	F-2
Iron (Fe), max	0.30
Oxygen (O), max	0.25
Carbon (C), max	0.08
Nitrogen (N), max	0.03
Hydrogen (H), max	0.015
Titanium (Ti)	Balance

Titanium Grade 2 Flange Mechanical Properties (Minimum)

Tensile Strength	Yield Strength (0.2%)	Elongation (4D)	Reduction of Area	Density
345 MPa (50 ksi)	275 MPa (40 ksi)	20%	30%	4.51 g/cm³ (0.163 lb/in³)

Check the current ASTM B381 edition (B381-26) and the mill certificate for governing values.

When Grade 2 Flanges Are Enough

Use Grade 2 for seawater and cooling water, wet chlorine, hypochlorite, nitric acid and most oxidising chloride service.
Step up to Grade 12 for hot brines, where the crevice under the gasket can corrode Grade 2.
Step up to Grade 7 where dilute hydrochloric or sulphuric acid is present.
Not suitable: hydrofluoric acid, fluorides and dry chlorine gas.

Need Grade 2 titanium flanges? Send the flange type, NPS, class, facing, bore schedule and quantity to kamlesh@dineshtube-india.com or call +91 83559 10913. You can also send an enquiry.

Marking, Gaskets and Bolting

Marking: a typical flange marking reads maker's mark, ASTM B381 F-2, size, class, facing, bore schedule and heat number.
Gaskets: use chloride-free gaskets such as PTFE-based types; avoid graphite in seawater service.
Bolting: choose bolt material for the outside environment; isolate dissimilar metals where seawater can bridge the joint.
Welding: GTAW with full argon shielding and internal purge, using ERTi-2 filler.

Titanium Grade 2 Flange Applications

Seawater cooling and fire-water piping
Desalination plant seawater lines
Chlor-alkali wet chlorine and brine piping
Heat exchanger and condenser nozzles
Offshore platforms and ship systems
PTA, nitric acid and pulp bleach-plant piping

Seawater, chlorine and chemical uses of titanium Grade 2 flanges

Titanium Grade 2 Flanges: FAQs

Which standard covers titanium Grade 2 flanges?

The flange material is covered by ASTM B381 (ASME SB381) Grade F-2, the specification for titanium forgings. Flange dimensions follow ASME B16.5, with B16.47 for sizes above 24" and EN 1092-1 on request.

What is F-2 titanium?

F-2 is the ASTM B381 forging grade of titanium Grade 2 (UNS R50400, Werkstoff 3.7035), commercially pure titanium. The "F" stands for forging.

Which types of Grade 2 flanges are available?

Weld neck, slip-on, blind, socket weld, threaded and lap-joint flanges, with raised face, flat face or ring-type-joint facing.

Do I need a solid Grade 2 flange, or will a lap-joint flange do?

In many lines a Grade 2 stub end with a carbon-steel or coated lap-joint backing flange is enough, because only the stub end touches the fluid. It is usually the lowest-cost way to flange titanium piping.

When should I use Grade 12 or Grade 7 flanges instead of Grade 2?

Grade 2 suits seawater, wet chlorine and most chloride service. Use Grade 12 for hot brines, where the crevice under the gasket can corrode Grade 2, and Grade 7 where dilute reducing acids are present.

What is the price of titanium Grade 2 flanges?

The price depends on flange type, NPS, class, facing, quantity and certification. Send your requirement to kamlesh@dineshtube-india.com or call +91 83559 10913 for a current quote.

Which certificates come with Grade 2 flanges?

Every supply comes with an EN 10204 3.1 mill test certificate showing heat number, chemical analysis and mechanical properties to ASTM B381. EN 10204 3.2 certificates and third-party inspection can be arranged on request.

Export Destinations for Titanium Grade 2 Flanges

We supply titanium Grade 2 flanges across India, including chlor-alkali, refinery, power and desalination projects in Gujarat, Maharashtra, Tamil Nadu, Andhra Pradesh and Odisha, and export to the Middle East (UAE, Saudi Arabia, Qatar, Oman, Kuwait, Bahrain), Asia (Bangladesh, Sri Lanka, Singapore, Malaysia, Vietnam, Indonesia), Africa (Egypt, Nigeria, South Africa) and Europe on request.