Titanium Flanges: Types, Grades and 12 Applications Explained

Опубликовано Engineering Team, Shaanxi Qianyi Tuoda Technology Co., Ltd от 2026-10-19

Titanium Flanges are the connection points in piping systems where corrosion, pressure and temperature all concentrate. They are specified across chemical electrolysis, sea water desalination, pharmaceutical clean service, hydrometallurgy, flue gas desulphurisation and vacuum salt production — anywhere a stainless flange would pit, and anywhere the joint has to survive decades rather than years.

Density is 4.51 g/cm³. Strength ranges from 240 MPa in commercially pure grades to 895 MPa in Ti-6Al-4V. Service temperature spans −253 °C to 600 °C. Available from DN10 to DN800, PN0.25 to PN25, in ASME B16.5, EN 1092-1, HG/T 20592 and GB/T configurations, with RF, FM, TG and RJ facings.

1. Five Structures and Where Each One Belongs

Structure is the first decision, and it is driven by three things: pressure class, temperature range and how often the joint will be opened for maintenance.

Type	Standard	Pressure Range	Where It Fits
Integral forged	HG/T 20592	PN0.6 – PN6.0	Low pressure, ambient temperature, joints rarely opened
Weld neck	ASME B16.5 / GB/T 9112	PN1.0 – PN25	High pressure, high temperature, frequent thermal cycling
Lap joint	GB/T 9112	PN0.25 – PN2.5	Frequent inspection, cost-controlled projects — the flange rotates free of the pipe
Threaded	GB/T 9114	PN0.6 – PN4.0	Thin-wall pipe, or where welding is not possible on site

The lap joint type is the one buyers underuse. Because the backing flange is free to rotate, bolt holes can be aligned without turning the pipe — which matters on a line that is dismantled every shutdown. The trade-off is a lower pressure rating, so it is not a substitute for a weld neck on a high-class joint.

2. Twelve Applications and the Grade That Suits Each

The grade question is answered by the medium. Below are the twelve duties we quote most often, with the reason each one calls for the grade it does.

#	Industry	Medium / Condition	Grade
1	Chlor-alkali	Saturated brine, electrolyte, wet chlorine, sodium hypochlorite, up to 120 °C	TA2
2	PTA (purified terephthalic acid)	Hot acetic acid with cobalt-manganese and bromide catalysts	TA10
3	Hydrometallurgy	Dilute sulphuric and hydrochloric acid, ammonium sulphate and chloride liquors	TA9 / TA10
4	Sea water desalination	Hot high-salinity brine, MED / MSF / RO evaporator and tube-sheet joints	TA2 / TA10
5	Oil and gas completion	H₂S, CO₂ and chlorides together, high temperature and pressure	TC4
6	Marine condensers	Flowing sea water, 30–50 °C, 1–3 m/s	TA2
7	Power plant condensers	Sea water, demineralised water, secondary-loop condensate	TA2 / TA10
8	Aerospace hydraulics	Hydraulic fluid, fuel, lubricant; −54 to 200 °C; 21–35 MPa	TC4
9	Food and pharmaceutical	Fermentation media, water for injection, organic solvents; CIP/SIP cleanable	TA2
10	Flue gas desulphurisation	Acidic slurry, pH 1–5, 50–80 °C, chloride and fluoride present	TA10
11	Vacuum salt production	Saturated sodium chloride brine, 50–130 °C, −0.08 MPa vacuum	TA2
12	Electroplating	Chrome, nickel and copper plating baths, pH 0.5–14	TA1

The reasoning behind the less obvious entries

Chlor-alkali (TA2). Saturated brine and wet chlorine are oxidising, and that is precisely where commercially pure titanium performs best — a stable passive film forms and holds. 316L in the same service begins pitting above roughly 80 °C. This is why titanium is the default material for membrane cell anode and cathode chamber flanges and chlorine header connections.

PTA (TA10). Hot acetic acid carrying cobalt-manganese and bromide catalysts is a reducing, halide-bearing environment. Unalloyed titanium is not sufficient here; the molybdenum and nickel in TA10 are what hold the passive film together. This is a genuine grade requirement, not an upsell.

Flue gas desulphurisation (TA10). The slurry is acidic, chloride-bearing and frequently also carries fluoride. TA10 is specified for the chloride resistance. Note that if the fluoride content is significant, titanium ceases to be the right material altogether — fluoride attacks titanium regardless of grade, and the answer becomes a nickel alloy.

Aerospace (TC4). This is the one application where the driver is strength rather than corrosion. At 21–35 MPa with a fatigue requirement and a weight penalty, Ti-6Al-4V at 895 MPa tensile and 4.43 g/cm³ is the only grade in this family that works.

Electroplating (TA1). The requirement here is purity — the flange must not shed metal ions into the plating bath, because contamination changes the deposit. TA1 is the lowest-alloy, highest-purity option, and the load on a tank cover flange is trivial.

3. The Five Grades, Side by Side

Grade	UNS / ASTM	Density	Tensile	Yield	Specify For
TA1	R50250 / Gr1	4.51 g/cm³	≥ 240 MPa	≥ 170 MPa	High-purity service, plating baths, low load, easy forming
TA2	R50400 / Gr2	4.51 g/cm³	≥ 345 MPa	≥ 275 MPa	Broadest coverage; the default when the duty is unclear
TA9	R52400 / Gr7	4.52 g/cm³	≥ 345 MPa	≥ 275 MPa	Reducing acids — dilute hydrochloric and sulphuric
TA10	R53400 / Gr12	4.51 g/cm³	≥ 485 MPa	≥ 345 MPa	Wet chlorine, dilute sulphuric acid, crevice corrosion
TC4	R56400 / Gr5	4.43 g/cm³	≥ 895 MPa	≥ 825 MPa	High-load structures, high pressure, thermal cycling

How to choose when the duty is not fully defined: TA2. It covers the widest range of media and is the grade most likely to be in stock, which matters when the line is already down.

How to choose when the duty is defined: wet chlorine or dilute sulphuric acid — TA10. Strongly reducing acid — TA9. High pressure and high load — TC4. High purity — TA1. And if the medium contains fluoride in any meaningful concentration, none of the five — the material changes to a nickel alloy.

One caution worth repeating: TC4 is not a premium version of TA2. It is roughly two and a half times the strength and materially less corrosion resistant in many chemical media, and it is harder to weld. Specify it because a mechanical calculation demands it, not because it sounds safer.

4. Standards and Facings

Four standard systems are in use, and they are not interchangeable — the same nominal pressure class produces different dimensions in each.

System	Standard	Coverage
Chinese national	GB/T 9112 – 9114	General steel pipe flange dimensions; pair with GB/T 21225 for titanium material
Chinese chemical	HG/T 20592 – 20635	Integral, weld neck, lap joint, threaded and blind — full range
American	ASME B16.5	Class 150 – 2500, NPS ½" – 24"; the export default
European	EN 1092-1	PN-designated metric flanges

Pressure class and PN do not convert reliably. Class 150 and PN16 are close but not identical, and the difference shows up in the bolt circle — an ASME Class 150 and an EN PN16 flange of the same nominal size will not consistently bolt together. Confirm the system and stay in it across the whole spool.

Facing	Code	Strength	Normally Used For
Raised face	RF	Widest availability, lowest cost	General service — the default
Male and female	FM / MFM	Gasket confined, better sealing reliability	Medium and high pressure chemical duty
Tongue and groove	TG	Gasket fully enclosed	Toxic or flammable media
Ring joint	RJ	Metal-to-metal seal	High temperature, high pressure oil and gas

RF and FM are the standard stock facings. TG and RJ are made to order. Whichever you specify, state the surface roughness alongside the code — RF at Ra 3.2–6.3 μm, and progressively finer for confined and ring joint facings. A facing code alone does not define the sealing surface.

5. How They Are Made, and Why It Matters

A titanium flange passes through five operations, and each one leaves a defect signature if it is done badly.

1. Forging. Open die or closed die, with a forging ratio of 3–5 recommended. The ratio is what breaks up the cast structure and gives the metal continuous flow lines. Under-forged stock retains casting porosity that no machining operation will remove.
2. Rough machining. The sealing face is left with 2–3 mm of stock for finish machining. This is the reason a flange cannot be re-faced indefinitely — there is a finite allowance.
3. Finish machining. The sealing face is machined to Ra 3.2–6.3 μm for a standard raised face. Bolt holes and location dimensions follow the standard tolerance.
4. Surface treatment. Pickling removes the oxide scale from hot working; passivation restores the passive film. A properly finished flange has an even silver-grey appearance — patchy or discoloured surfaces suggest the pickling was incomplete.
5. Non-destructive testing. 100% penetrant testing (PT) or 100% ultrasonic testing (UT) as standard; radiographic testing (RT) added for critical duty.

Why the testing line matters commercially. PT finds surface-breaking defects; UT finds what is inside — shrinkage cavity, inclusion, lamination. A flange with an internal void passes every dimensional check and every visual inspection, then fails under pressure at temperature once the line is commissioned. At that point the cost is not the flange, it is the shutdown.

6. Five Things That Go Wrong in the Supply Chain

Grade substitution. TA1 shipped where TA2 was ordered, or another alloy shipped as TC4. The parts are visually identical. Mill test certificates can be photocopied. The only reliable check is a spectrometer reading on a sample from the delivered lot.

Welded-over cracks. A forging crack dressed out and welded flush will pass a visual inspection and fail in service. PT on 100% of the part is what exposes it — this is the single most useful test to require on a forged flange.

Roughness out of specification. A sealing face at Ra 12.5 μm instead of 3.2–6.3 μm looks fine and leaks at temperature. Require a roughness record with the goods, and check it on receipt with a comparator or profilometer.

Dimensional error on the bolt pattern. Bolt circle diameter or hole spacing out of tolerance means the flange will not align with its mating part on site. This is checked in minutes with a caliper against the standard table, and it is the cheapest defect to catch before shipment.

No real non-standard capability. Some suppliers can only modify the dimensions of a standard part. Ask specifically about non-standard geometry — irregular outlines, variable thickness, titanium-steel composite flanges — before placing the order, not after.

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We hold Titanium Flanges in TA1, TA2, TA9, TA10 and TC4 across integral, weld neck, lap joint and threaded structures, from DN10 to DN800 and PN0.25 to PN25, in ASME B16.5, EN 1092-1, HG/T 20592 and GB/T configurations. Non-standard flanges, irregular shapes and titanium-steel composite parts are made to drawing. Stock items dispatch in 3–5 working days; custom parts typically 7–15 days.

Send us the medium, temperature, pressure class, standard system and facing code — we will confirm the grade and provide the mill certificate, roughness record and NDT report with the quotation.

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