Titanium Grade 7 Flanges

Titanium Grade 7 (F-7, Ti-0.15Pd, UNS R52400) Flanges to ASTM B381 and ASME B16.5

Dinesh Tube India supplies and exports titanium Grade 7 flanges from Mumbai for acid, chlor-alkali, hydrometallurgy and chemical piping in India and abroad. Grade 7 flanges are machined from forgings to ASTM B381 / ASME SB381 Grade F-7 (UNS R52400, Werkstoff 3.7235), with dimensions to ASME B16.5, and are supplied with EN 10204 3.1 mill test certificates.

Grade 7 is commercially pure titanium with 0.12–0.25% palladium, the most corrosion-resistant of the common titanium grades in dilute reducing acids. The gasket face of a flange is a tight crevice, often the first place a lower grade corrodes, so in acid lines the flanges should match the Grade 7 pipe and Grade 7 fittings. For all grades, see our titanium flanges page.

Table of Contents

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

Titanium Grade 7 F-7 flanges to ASTM B381

Titanium Grade 7 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 7 Stub End with Backing Flange

A solid Grade 7 flange is not always needed. In a lap-joint assembly, only the stub end touches the process fluid, so it is made in Grade 7 while the loose backing flange can be carbon steel, coated steel or stainless steel. With palladium-bearing Grade 7 this saves the most material cost, and the loose flange also makes bolt-hole alignment easier.

Stub end: Grade 7 (WPT7) to ASTM B363, long or short pattern. See Grade 7 pipe fittings.
Backing flange: lap-joint flange to ASME B16.5 in a cheaper material.
When to use solid F-7: where the flange face or bore is wetted, for blind flanges, or where the specification requires it.

F-7 vs F-12 vs F-2 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
Dilute reducing acids (HCl, H₂SO₄)	Poor to fair	Good	Best
Crevice corrosion under gaskets in hot brines	Fair	Excellent	Excellent
Cost and availability	Lowest; widest range	Moderate	Highest; mostly to order

F-16 (Grade 16, Ti-0.05Pd) has about a third of the palladium of Grade 7 and is sometimes accepted as a lower-cost alternative; check your specification first.

Titanium Grade 7 Flange Chemical Composition (ASTM B381 F-7, %)

Element	F-7
Palladium (Pd)	0.12–0.25
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 7 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.

Why Grade 7 Flanges in Acid Service?

Gasket crevices: the area under the gasket is a tight crevice where acid concentrates; Grade 7 stays passive there where Grade 2 can corrode.
Reducing acids: palladium keeps titanium passive in dilute hydrochloric and sulphuric acid.
When F-12 is enough: for hot brines without acid, Grade 12 flanges give similar crevice resistance at lower cost.
Limits: not intended for hot, concentrated HCl or H₂SO₄, where zirconium or tantalum may be needed; not suitable for hydrofluoric acid or dry chlorine.

Need Grade 7 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-7, 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 matching ERTi-7 filler.

Titanium Grade 7 Flange Applications

Dilute hydrochloric and sulphuric acid process lines
Chlor-alkali and chlorine dioxide plants
Hydrometallurgy leaching and autoclave piping
Hot brine and high-chloride process piping
PTA, acetic acid and fine-chemical plants

Acid, chlor-alkali and chemical uses of titanium Grade 7 flanges

Titanium Grade 7 Flanges: FAQs

Which standard covers titanium Grade 7 flanges?

The flange material is covered by ASTM B381 (ASME SB381) Grade F-7, the specification for titanium forgings. Flange dimensions follow ASME B16.5, with EN 1092-1 on request.

What is F-7 titanium?

F-7 is the ASTM B381 forging grade of titanium Grade 7 (UNS R52400, Werkstoff 3.7235), commercially pure titanium with 0.12–0.25% palladium.

Why use Grade 7 flanges in acid service?

The gasket face of a flange is a tight crevice where acid concentrates. Grade 7's palladium keeps titanium passive there in dilute hydrochloric and sulphuric acid, where Grade 2 flanges can corrode.

Do I need a solid Grade 7 flange, or will a lap-joint flange do?

In many lines a Grade 7 stub end with a carbon-steel or coated lap-joint backing flange is enough, because only the stub end touches the fluid. With palladium-bearing Grade 7 this saves the most material cost.

Should I choose F-7 or F-12 flanges?

F-7 is best where reducing acids are present. F-12 is stronger and lower cost and is usually enough for hot brines without acid. Match the flange grade to the pipe grade.

What is the price of titanium Grade 7 flanges?

Grade 7 costs more than Grade 2 and Grade 12 because of its palladium content, and flanges are mostly made to order. Send the flange type, NPS, class and quantity to kamlesh@dineshtube-india.com or call +91 83559 10913 for a quote.

Which certificates come with Grade 7 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 7 Flanges

We supply titanium Grade 7 flanges across India, including chemical, chlor-alkali and hydrometallurgy projects in Gujarat, Maharashtra, Tamil Nadu and Andhra Pradesh, and export to the Middle East (UAE, Saudi Arabia, Qatar, Oman, Kuwait, Bahrain), Asia (Japan, South Korea, Singapore, Malaysia, Vietnam, Bangladesh), Africa (Egypt, South Africa) and Europe on request.