Titanium Flanges: From Material Selection to Seal Failure (2026 Revision)

The disc body is equipped with a circle of bolt holes, which seems to be a standardized connector, but it is a high-risk position for titanium equipment failure.Industry data show that 80% of titanium equipment early leakage problems are from flange sealing surfaces.This article comprehensively explains from the aspects of material characteristics, sealing forms, implementation standards, selection and procurement, etc.Titanium flangeFor reference by engineering designers and purchasers.

In the chemical equipment system, flanges simultaneously assume multiple functions of equipment connection, medium sealing, disassembly and maintenance.Titanium equipment body service life can reach 15 to 20 years, but flange sealing surface often occurs leakage within 2 to 3 years.Most of these failures are not corrosion failures of titanium itself, It's a sealed solution., fastener selection, gasket matching, Caused by irregular on-site installation and construction.

Titanium flangeAnd ordinary steel flanges have obvious performance differences.304/316L steel flanges will corrode and fail in 1 to 3 years in wet chlorine and seawater corrosion conditions.Titanium Flangestable use for more than 15 years;Titanium materials are prone to titanium and titanium contact surface bite, need to match titanium steel transition gasket;Stress relaxation exists in titanium bolts, and the stress can be reduced by 20%~30% within half a year.Titanium flangeThe purchase price is 1.5 to 3 times that of steel flanges, At the same time, the titanium sealing surface work hardening is obvious, It is more difficult to manufacture.

According to the statistics of Titanium Zirconium Branch of China Nonferrous Metals Industry Association, in 2024, ChinaTitanium flangeThe market scale is about RMB 2.4 billion yuan, with an annual growth rate of 22%.Titanium steel composite flange growth rate is the fastest, allTitanium flangeThe proportion of categories increased from 15% in 2020 to 38% in 2024.

According to HG/T20592 and ASME B16.5,Titanium flangeDivided into a variety of structural forms.Flat welding flange is single layer plate without neck, suitable for low pressure pipeline within 1.0MPa;Flanges with neck plain welding with short neck, smooth transition, titanium clad plate equipment is commonly used selection;Long neck structure with neck butt welding flange, the stress distribution is more reasonable, Suitable for high temperature and high pressure cycle conditions above 4.0MPaThe integral flange is forged in one body and is mostly used for connecting pipes of high-pressure equipment;Socket welding flange is suitable for small diameter instrument interface within DN50;Threaded flanges rely on pipe thread connections for temporary maintenance of pipelines;Titanium steel composite flange sealing surface for titanium material, the body of steel, can reduce 40%~60% procurement cost.

Seal surface form includes raised surface RF, Concave-convex surface M/F, Mortise surface T/G, Ring joint RTJ, Full plane FF.Protrusions are most widely used and suitable for conventional corrosive media.Concave-convex surface has good neutralization effect, suitable for wet chlorine and acidic medium;Mortise surface sealing performance is excellent, mostly used for high-risk media;Ring connection surface rely on metal ring to achieve self-sealing, for high temperature and high pressure conditions;Full plane is mostly used for butt joint with cast iron and FRP lining plastic equipment.

Material selection, TA1, TA2, TA3 industrial pure titanium suitable for wet chlorine, seawater, dilute hydrochloric acid, acetic acid;TA9 titanium palladium alloy, TA10 titanium molybdenum nickel alloy suitable for dilute sulfuric acid, phosphoric acid such as reducing corrosion medium;TC4 titanium alloy for high intensity pressure scenarios;Nickel alloy can be used in strong alkali, high temperature wet hydrogen chloride conditions;Titanium steel composite, titanium stainless steel composite flange both corrosion resistance and project cost.

Titanium Flangesignificant difference between machined and stainless steel flanges, Titanium absorbs hydrogen when the temperature exceeds 400℃, oxygen uptake, Fast work hardening speed, The whole process requires argon protection and the use of special tools.Complete process flow: raw material incoming inspection, check material certificate and complete ultrasonic, mechanical, chemical composition re-inspection;forging or sheet blanking is adopted according to blank type;forging temperature of 950-1050 DEG C is controlled to ensure forging ratio;roughing allowance;annealing at 550-650 deg.c;CNC finishing, sealing surface control roughness Ra≤0.8μm;Complete bolt hole drilling and tapping;pickling passivation treatment;Carry out appearance, size and hardness testing, 100% penetration and ultrasonic testing of important forgings;Conduct hydraulic test according to 1.5 times design pressure;Mark the batch number of material furnace, vacuum nitrogen-filled packaging.

Titanium flange processing workshop must be independent partition, carbon steel tools are prohibited to contact titanium parts.Iron pollution is the main cause of titanium flange failure, Partial pitting corrosion will be caused by iron filings embedded in titanium sealing surface, Medium leakage occurs in a short time.Grinding wheel shall not be used for cutting, special cutting tools and chlorine-free cutting fluid shall be selected for cutting, and double-sided argon protection shall be adopted for welding.

There is no special national standard for titanium flange in China, and the project selection adopts multi-standard combination.Blank refer to GB/T27684, ASTM B381;Flange geometric size PN series refer to HG/T20592, American Standard Class system refer to ASME B16.5;Material designation complies with GB/T3620.1;Non-destructive testing implements NB/T47013 series;Weld qualification is performed NB/T47014.GB/T27684 is suggested for the procurement contract, HG/T20592 and technical requirements of drawings shall be taken as the basis for implementation.

Titanium flange selection six-step method: the first step to determine the medium composition, temperature, pressure, chloride ion content;secondly, selecting a titanium material grade;Step 3 Select PN or Class pressure rating;step four, determine that form of the sealing surface;fifth, determining the flange structure;Step 6: Specify acceptance levels for nondestructive testing.Material designation shall be specified in the procurement contract, DN and pressure rating, flange structure, sealing surface roughness, Duty Parameter, executive standard, test item, surface treatment, Warranty period and complete set of deliverables.

Procurement needs to focus on avoiding six major quality risks: titanium sealing surface iron ion pollution;Insufficient welding protection produces a blue-purple oxide layer;Work hardening is not de-stressed;Seal surface roughness exceeds standard;Bolt hole position deviation;Pressure forgings omit ultrasonic testing.Domestic titanium flange manufacturing process mature, DN2000 specifications can be stable production, Compared with imported products, procurement costs can be greatly reduced.Titanium steel composite bolts and nuts are recommended for matching fasteners, Flexible graphite titanium inner ring is selected according to working conditions, PTFE or titanium ring pad, Try to avoid pure titanium bolts, Prevention of biting, Stress relaxation.

Titanium flange industry three development directions: titanium steel explosion welding composite flange continued to popularize, effectively control project cost;Large diameter DN2000~3000mm titanium flange demand growth, For large forging, Heat treatment process requirements upgradeAI vision inspection, digital stress simulation and other digital processes are gradually applied to improve product stability.

Relying on Baoji China Titanium Valley Industrial Advantage, Shaanxi Qianyi Tuoda Technology can customize TA 2 production, TC4 pure titanium flange and titanium steel composite flange, Product supporting material certificate, Forgings Information, nondestructive testing report, Chlorine alkali, wet desulfurization, Seawater desalination and other chemical corrosion equipment projects.

What about TA2 and TA10?Comparison of 3 real working conditions, reasonable material selection can save costs Titanium non-standard equipment "Sky round ground square" pipe fittings: from process principle to selection standard (2026 revision) TA2 Titanium PlateTrue and false discrimination| 5-Step Depth Discrimination Guide