China titanium piping solution supplier: www.titaniuminfogroup.com

What is a titanium pipe?

What is a titanium pipe?

Titanium pipe is light in weight, high in strength and excellent in mechanical properties. It is widely used in heat exchange equipment, such as tubular heat exchanger, coil heat exchanger, serpentine heat exchanger, condenser, evaporator and transmission pipeline. Many nuclear power industries use titanium pipes as their unit standard pipes. According to the material, it can be divided into pure titanium pipe and alloy pipe. According to the processing technology, it can be divided into seamless pipe and welded pipe. As the raw material for the production of finished pipe, pipe blank is also used to make pipe target (pure titanium) for vacuum coating. Pure titanium pipe can be used to produce titanium coil, such as heat exchange, heating pipe, condensing pipe and pipe on heat exchanger.

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  • Ti Tube Standards: ASTM B338, B861, B862, DIN 17 861, AMS 4941, AMS 4942
  • Tube Type: Welded Tube / Seamless Tube
  • Grade Material: CP Grades 1 – 4, Alloys: Grade 5, 7, 9, 12, 24, 26, 29
  • Seamless Tube Dimensions:
    • Outer Diameter Range: 0.5 – 330 mm
    • Wall Height Range: 0.4 – 10 mm
    • Length Range: < 15000 mm
  • Welded Tube Dimensions:
    • Outer Diameter Range: 114 – 5,000 mm
    • Wall Height Range: 0.5mm – 50mm
    • Length Range: < 15000 mm

Pipe Size Chart

The NPS is a commonly used titanium tube sizing standard for pipes used for high pressure and temperature applications, along with the DN standard used in Europe. We manufacture titanium pipes to both standards and also customer defined requirements.

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Titanium Pipe Sizing Standards – NPS ⅛ to NPS 24
NPS DN OD[in (mm)] Wall thickness[in (mm)]
SCH 5 SCH 10s / 10 SCH 30 SCH 40s / 40 / STD SCH 80s / 80 / XS SCH 120 SCH 160 XXS
6 0.405 (10.29) 0.035 (0.889) 0.049 (1.245) 0.057 (1.448) 0.068 (1.727) 0.095 (2.413)
¼ 8 0.540 (13.72) 0.049 (1.245) 0.065 (1.651) 0.073 (1.854) 0.088 (2.235) 0.119 (3.023)
10 0.675 (17.15) 0.049 (1.245) 0.065 (1.651) 0.073 (1.854) 0.091 (2.311) 0.126 (3.200)
½ 15 0.840 (21.34) 0.065 (1.651) 0.083 (2.108) 0.095 (2.413) 0.109 (2.769) 0.147 (3.734) 0.188 (4.775) 0.294 (7.468)
¾ 20 1.050 (26.67) 0.065 (1.651) 0.083 (2.108) 0.095 (2.413) 0.113 (2.870) 0.154 (3.912) 0.219 (5.563) 0.308 (7.823)
1 25 1.315 (33.40) 0.065 (1.651) 0.109 (2.769) 0.114 (2.896) 0.133 (3.378) 0.179 (4.547) 0.250 (6.350) 0.358 (9.093)
32 1.660 (42.16) 0.065 (1.651) 0.109 (2.769) 0.117 (2.972) 0.140 (3.556) 0.191 (4.851) 0.250 (6.350) 0.382 (9.703)
40 1.900 (48.26) 0.065 (1.651) 0.109 (2.769) 0.125 (3.175) 0.145 (3.683) 0.200 (5.080) 0.281 (7.137) 0.400 (10.160)
2 50 2.375 (60.33) 0.065 (1.651) 0.109 (2.769) 0.125 (3.175) 0.154 (3.912) 0.218 (5.537) 0.250 (6.350) 0.343 (8.712) 0.436 (11.074)
65 2.875 (73.03) 0.083 (2.108) 0.120 (3.048) 0.188 (4.775) 0.203 (5.156) 0.276 (7.010) 0.300 (7.620) 0.375 (9.525) 0.552 (14.021)
3 80 3.500 (88.90) 0.083 (2.108) 0.120 (3.048) 0.188 (4.775) 0.216 (5.486) 0.300 (7.620) 0.350 (8.890) 0.438 (11.125) 0.600 (15.240)
90 4.000 (101.60) 0.083 (2.108) 0.120 (3.048) 0.188 (4.775) 0.226 (5.740) 0.318 (8.077) 0.636 (16.154)
NPS[5] DN
[2]
OD
[in (mm)]
Wall thickness
[in (mm)]
SCH 5 SCH 10s/10 SCH 20 SCH 30 SCH 40s/40
/STD
SCH 60 SCH 80s/80
/XS
SCH 100 SCH 120 SCH 140 SCH 160 XXS[5]
4 100 4.500 (114.30) 0.083 (2.108) 0.120 (3.048) 0.188 (4.775) 0.237 (6.020) 0.281 (7.137) 0.337 (8.560) 0.437 (11.100) 0.531 (13.487) 0.674 (17.120)
115 5.000 (127.00) 0.247 (6.274) 0.355 (9.017) 0.710 (18.034)
5 125 5.563 (141.30) 0.109 (2.769) 0.134 (3.404) 0.258 (6.553) 0.375 (9.525) 0.500 (12.700) 0.625 (15.875) 0.750 (19.050)
6 150 6.625 (168.28) 0.109 (2.769) 0.134 (3.404) 0.280 (7.112) 0.432 (10.973) 0.562 (14.275) 0.719 (18.263) 0.864 (21.946)
7[5] 7.625 (193.68) 0.301 (7.645) 0.500 (12.700) 0.875 (22.225)
8 200 8.625 (219.08) 0.109 (2.769) 0.148 (3.759) 0.250 (6.350) 0.277 (7.036) 0.322 (8.179) 0.406 (10.312) 0.500 (12.700) 0.593 (15.062) 0.719 (18.263) 0.812 (20.625) 0.906 (23.012) 0.875 (22.225)
9[5] 9.625 (244.48) 0.342 (8.687) 0.500 (12.700)
NPS[5] DN
[2]
OD
[in (mm)]
Wall thickness
[in (mm)]
SCH 5s SCH 5 SCH 10s SCH 10 SCH 20 SCH 30 SCH 40s/STD
10 250 10.75 (273.05) 0.134 (3.404) 0.134 (3.404) 0.165 (4.191) 0.165 (4.191) 0.250 (6.350) 0.307 (7.798) 0.365 (9.271)
12 300 12.75 (323.85) 0.156 (3.962) 0.165 (4.191) 0.180 (4.572) 0.180 (4.572) 0.250 (6.350) 0.330 (8.382) 0.375 (9.525)
14 350 14.00 (355.60) 0.156 (3.962) 0.156 (3.962) 0.188 (4.775) 0.250 (6.350) 0.312 (7.925) 0.375 (9.525) 0.375 (9.525)
16 400 16.00 (406.40) 0.165 (4.191) 0.165 (4.191) 0.188 (4.775) 0.250 (6.350) 0.312 (7.925) 0.375 (9.525) 0.375 (9.525)
18 450 18.00 (457.20) 0.165 (4.191) 0.165 (4.191) 0.188 (4.775) 0.250 (6.350) 0.312 (7.925) 0.437 (11.100) 0.375 (9.525)
20 500 20.00 (508.00) 0.188 (4.775) 0.188 (4.775) 0.218 (5.537) 0.250 (6.350) 0.375 (9.525) 0.500 (12.700) 0.375 (9.525)
22 550 22.00 (558.80) 0.188 (4.775) 0.188 (4.775) 0.218 (5.537) 0.250 (6.350) 0.375 (9.525) 0.500 (12.700) 0.375 (9.525)
24 600 24.00 (609.60) 0.218 (5.537) 0.218 (5.537) 0.250 (6.350) 0.250 (6.350) 0.375 (9.525) 0.562 (14.275) 0.375 (9.525)

Specifications of Titanium Pipe

Specifications of Titanium Seamless Pipe

Dimension Outer Diameter Thickness Length
Size Range: 0.5mm – 330mm 0.4mm – 10mm Max 15m
Manufacturing Standards ASTM B338ASTM B861DIN 17 861

Specifications of Titanium Welded Pipe

Dimension Outer Diameter Thickness Length
Size Range: 114mm – 20000mm 0.5mm – 50mm Max 15m
Manufacturing Standards ASTM B338ASTM B862

Properties of seamless titanium pipe

1. Seamless titanium pipe.

Titanium pipe has high strength. Titanium alloy has very high strength, its tensile strength is 686-1176mpa, and its density is only about 60% of steel, so its specific strength is very high.

2. The hardness of seamless titanium pipe is high.

The hardness HRC of titanium alloy (as annealed) is 32-38.

3. The elastic modulus of seamless titanium pipe is low.

The elastic modulus of titanium alloy (annealed) is 1.078 × 10-1.176 × 10MPa, about half of that of steel and stainless steel. Executive Standards: ASTM B337, ASTMB338, ASTM B338 B861

4. Excellent high and low temperature performance.

At high temperature, titanium alloy can still maintain good mechanical properties, its heat resistance is higher than that of aluminum alloy, and its working temperature range is wide. At present, the working temperature of the new heat-resistant titanium alloy can reach 550-600 ℃; at low temperature, the strength of titanium alloy is higher than that at normal temperature, and it has good toughness. At – 253 ℃, the low temperature titanium alloy can still maintain good toughness.

5. Seamless titanium pipe has strong corrosion resistance.

When titanium is in the air below 550 ℃, a thin and compact titanium oxide film will form on its surface. Therefore, its corrosion resistance is better than that of most stainless steels in the oxidizing media such as atmosphere, sea water, nitric acid, sulfuric acid and strong alkali. Seamless titanium pipe is made by extrusion technology, and welded titanium pipe is made by welding after plate curling. Generally, the wall thickness of seamless titanium pipe is relatively small, and the caliber is also relatively small.

Chemical Composition of Titanium Pipe

Titanium Grade 1-4 is pure Titanium, the other grades are alloys. Pure Titanium is used due to its high corrosion resistance, the alloys because of the extremely high strength to weight ratio.

  • Grade 1. Pure Titanium, relatively low strength and high ductility.
  • Grade 2. The pure titanium most used. The best combination of strength, ductility and weldability.
  • Grade 3. High strength Titanium, used for Matrix-plates in shell and tube heat exchangers.
  • Grade 5. The most manufactured titanium alloy. Exceedingly high strength. High heat resistance.
  • Grade 7. Superior corrosion resistance in reducing and oxidizing environments.
  • Grade 9. Very high strength and corrosion resistance..
  • Grade 12. Better heat resistance than pure Titanium. Applications as for Grade 7 and Grade 11.
  • Grade 23. Titanium-6Aluminum-4Vanadium ELI (Extra Low Interstitial) Alloy for surgical implant Applications.

CHEMICAL, PHYSICAL AND
MECHANICAL PROPERTIES

CHEMICAL COMPOSITION

ASTM Grade

(Max. Values)

1

2

5

7

9

12

23

N, Nitrogen

0,03

0,03

0,05

0,03

0,02

0,03

0,03

C, Carbon

0,1

0,1

0,1

0,1

0,05

0,08

0,08

H, Hydrogen

0,015

0,015

0,0125

0,015

0,013

0,015

0,0125

Fe, Iron

0,2

0,3

0,4

0,3

0,25

0,3

0,25

O, Oxygen

0,18

0,25

0,20

0,25

0,12

0,25

0.13

Pd, Palladium

0,12-0,25

Al, Aluminum

5,5-6,75

2,5-3,5

5,5-6.5

Mo, Molybdenum

0,2-0,4

V, Vanadium

3,5-4,5

2,0-3,0

3,5-4,5

Ni, Nickel

0,6-0,9

Ti, Titanium

Bal.

Bal.

Bal.

Bal.

Bal.

Bal.

Bal.

MECHANICAL PROPERTIES

Tensile strength, min (Mpa)

240,00

345,00

895,00

345,00

620,00

483,00

828,00

Yield strength, 0,2% Offset,
min (Mpa)

170,00

275,00

825,00

275,00

483,00

345,00

759,00

Elongation (in 4D, min, %)

24,00

20,00

10,00

20,00

15,00

18,00

10,00

Reduction of Area, min, %

30,00

30,00

25,00

30,00

25,00

25,00

15,00

Hardness * Interpolated

Rb70

Rb80

Rc36

Rb80

Rc28

Rc17*

List of ASTM Grades 

ASTM Grade

Description

1

Unalloyed Titanium – Low Oxygen

2

Unalloyed Titanium – Standard Oxygen

3

Unalloyed Titanium – Medium Oxygen

4

Unalloyed Titanium – High Oxygen

5

Titanium – 6%Al – 4%V

6

Titanium – 5%Al – 2.5%Sn

7

Unalloyed titanium plus 0.12 % to 0.25 % Pd, standard oxygen,

9

Titanium – 3%Al – 2.5%V

10

Titanium – 11.5%Mo – 6%Zr – 4.5%Sn

11

Unalloyed titanium plus 0.12 % to 0.25 % Pd, low oxygen,

12

Titanium – 0.3%Mo – 0.8%Ni

13

Titanium – 0.5%Ni – 0.05%Ru, low oxygen

14

Titanium – 0.5%Ni – 0.05%Ru, standard oxygen

15

Titanium – 0.5%Ni – 0.05%Ru, medium oxygen

16

Unalloyed titanium plus 0.04 % to 0.08 % Pd, standard oxygen,

17

Unalloyed titanium plus 0.04 % to 0.08 % Pd, low oxygen

18

Titanium alloy – 3%Al – 2.5 %V plus 0.04 % to 0.08 % Pd

19

Titanium – 3%Al – 8%V – 6%Cr – 4%Zr – 4%Mo

20

Titanium – 3%Al – 8%V – 6%Cr – 4%Zr – 4%Mo plus 0.04% to 0.08%Pd

21

Titanium – 15%Mo – 3%Al – 2.7%Nb – 0.25%Si

23

Titanium – 6%Al – 4%V, extra low interstitial, (ELI)

24

Titanium – 6%Al – 4%V plus 0.04 % to 0.08 %Pd

25

Titanium – 6%Al – 4%V plus 0.3% to 0.8%Ni and 0.04% to 0.08 %Pd

26

Unalloyed titanium plus 0.08 to 0.14 %Ru, standard oxygen

27

Unalloyed titanium plus 0.08 to 0.14 %Ru, low oxygen

28

Titanium – 3%Al – 2.5%V plus 0.08-0.14 %Ru

29

Titanium – 6%Al – 4%V, extra low interstitial, (ELI) plus 0.08-0.14 %Ru

30

Titanium – 0.3%Co – 0.05%Pd, standard oxygen

31

Titanium – 0.3%Co – 0.05%Pd, medium oxygen

32

Titanium – 5%Al – 1%V – 1%Sn – 1%Zr – 0.8%Mo

33

Titanium – 0.4%Ni – 0.015%Pd – 0.025%Ru – 0.15%Cr, standard oxygen

34

Titanium – 0.4%Ni – 0.015%Pd – 0.025%Ru – 0.15%Cr, medium oxygen

35

Titanium – 4.5%Al – 2%Mo – 1.6%V – 0.5%Fe – 0.3%Si

What are the uses for titanium pipe?

Titanium pipe is being used in an increasing number of applications because there are so many cases in which stainless steel and other materials are simply insufficient. Tubing is one of the common titanium mill products, and it is used in a range of products because of its superior strength-to-weight ratio and corrosion resistance. Let’s take a deeper look at titanium pipe and what it is commonly used for.

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Application of seamless titanium pipe

1. Military seamless titanium pipe
For typhoon class nuclear submarines, seamless titanium tubes are widely used in military industry. Nuclear powered submarines, hydrofoil boats, mortar tubes, anti tank missiles, missile launchers, tank shields and bulletproof vests use a large number of titanium tubes. It is understood that the use of titanium tubes is as high as 9000 tons, which shows that the military industry has a huge demand for titanium tubes.
2. Application of seamless titanium pipe in aerospace
The number of titanium tubes used in civil aircraft accounts for about 20-25% of the weight of the frame. In addition, a large number of titanium tubes are also used in strategic rocket engines, spacecraft (such as Shenzhou 5 and Shenzhou 6) and satellite antennas. Titanium tubes are widely used in aviation industry.
3. Application of seamless titanium pipe in marine industry
Seamless titanium pipe has corrosion resistance, which can not be compared with other metal materials. Especially in seawater, it can withstand high-speed corrosion. At present, the United States, Japan, France and other countries have developed various advanced titanium controlled deep submersibles, submarines and submarine laboratory equipment for marine research. In addition, titanium control equipment and devices have been widely used in coastal power stations, offshore oil production equipment, seawater desalination, marine chemical product production and marine aquaculture.
4. Application in chemical industry
The types of equipment have developed from small and single to large and diverse. According to the prediction of the chemical industry department, the application of seamless titanium pipe equipment has expanded from the original soda and caustic soda industry to the whole chemical industry. The number of titanium tubes used in the chemical industry will exceed 1500 tons per year. State owned vacuum salt enterprises gradually began to use titanium tube metal materials to manufacture equipment, and the corrosion of equipment has been greatly improved.
5. Application in oil refining
Sulfide, chloride and other corrosive substances in petroleum processing products and cooling water. In the process of petroleum refining, the condensing equipment of atmospheric tower and vacuum tower in refinery, especially low-temperature light oil, is highly corrosive. One of the outstanding issues. In recent years, the United States, Japan and other countries have introduced seamless titanium control equipment for these high corrosion links, and achieved good results.
6. Application in automobile industry
Titanium tubes have been used in racing cars for many years. The lightweight and high strength characteristics of titanium tubes have always been the focus of automobile manufacturers. At present, almost all titanium tubes are used for racing. The number of titanium tubes for automobiles in Japan has exceeded 600 tons. With the development of the global automobile industry, titanium tubes for automobiles are still growing rapidly.
7. Application in medicine
With the progress of medical technology, metal implantation into the human body is a very rare surgical operation. Due to the weak rejection between seamless titanium tube and human tissue, it is widely used in human bone implants, such as artificial bone, artificial joint and artificial tooth. In addition, the application of titanium tubes in pharmaceutical machinery and medical equipment has been further recognized, and the future demand should not be underestimated.
8. Demand of titanium and titanium alloy tubes in shipbuilding industry

  • 1) Submarine. Russia is an international leader in the research and manufacturing skills of creating titanium alloy submarines. It is also the first country to create pressure resistant shells with titanium alloy titanium tubes. At its peak, the annual output of titanium alloy thick plates and pipes for submarines reached 10000 tons, accounting for 30-50% of the annual output of titanium alloy processing. Since the 1960s, Russia has developed four generations of submarines. Russia created the first “Alfa” class submarine in 1970. In the 1970s-1980s, six submarines were built successively, each with about 3000t titanium. The typical application of titanium on ships, such as the Russian typhoon submarine, has a shell made of titanium alloy. Due to military needs, the double shell layout is selected. Its double shell shares 9000t of titanium, making it non-magnetic, deep diving, fast speed, low noise and less repair times.
  • (2) Titanium alloy ship. Japan Tsai has good practical experience in making titanium ships. In the 1990s, DONGBANG titanium company, Nisheng industry company, Tengxin shipyard and Jiangteng shipyard all created all titanium fishing boats or speedboats. The advantages of titanium alloy ship are light weight, fast speed, small engine, low fuel cost, low carbon dioxide emission, no need for external coating, easy sorting of attachments, etc. the defects are high data cost, difficult processing and manufacturing skills and strict maintenance requirements. The results of the ship test show that the functions of ship speed, stability and noise are very good.
  • (3) Atomic powered ship. Russia uses titanium alloy instead of stainless steel to make ship steam engine, heat exchanger and cooler, which overcomes corrosion damage. Titanium steam engines are widely used in the power plants of existing atomic powered icebreakers in Russia. The use of titanium alloy can extend the service life of the engine by more than 10 times.
  • (4) Related parts of deep submersibles and rescue boats. The United States, Japan and France have successively created deep submersibles. The pressure shell is made of titanium and titanium alloy. Meanwhile, there are American aivin, sea cliff submersible, French sm97, Japanese deep-sea “2000”, and American Navy deep-sea rescue boat.
  • (5) Sonar shroud. Titanium alloy sonar deflector has superior function and is used in the sonar system of Russian aircraft carriers “Kursk”, “titanium plate Minsk” and “Kiev”. According to the different requirements of underwater and surface applications, at present, there are basically two kinds of shell plate sound transmission data for the sonar fairing of ships in service in China, one is stainless steel and the other is fiber-reinforced FRP.
  • (6) Propeller. The propeller has high data demand intensity, good fatigue function in seawater medium, erosion resistance and cavitation corrosion resistance. Titanium alloy can meet the above summarized functional requirements. American sailors first used 1500mm diameter four blade detachable supercavitation titanium alloy propeller on hydrofoil boats. China developed hydrofoil speedboat propeller in 1972, and has produced various titanium alloy propellers with a diameter of 450-1100mm. Long term application shows that the service life of titanium alloy propeller exceeds that of copper alloy propeller by more than 5 times.
  • (7) Ship pumps, valves and piping. Because the working conditions of pumps, valves and pipes on ships are very poor, the service life of pipes made of copper and stainless steel is only 2-5 years. After replacing titanium alloy, it has excellent effect and is suitable for moving seawater pipeline with high flow rate. The life rule of Russian ship pipeline has three life requirements. That is, the time limit for the first docking repair is 8-9 years; The service life shall not be less than 15 years. Full life requires that all classes of ships should operate reliably within 25-30 years.

What is the right grade to use?

Most grades of titanium are approved for pressurized service, meaning there are many different options out there. While all grades are usable, grade 2 is the one that is employed in most situations. This grade is readily available, which also makes it a good choice for quick production runs as well as larger orders.

Production process of titanium pipe

The production process of industrial pure titanium pipe is as follows:

Surface treatment – blanking – rolling – degreasing – drying – cut to length – annealing – straightening – Pickling – rolling – degreasing of finished products – drying – annealing – straightening – cut to length of finished products – Pickling – Inspection – packaging

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(Note: the above processes can be added or reduced according to product specifications and performance requirements. )

For the titanium tube blank lubricated by copper plating before rolling, a copper removal process is added before the surface treatment of this process.

Pickling process

In the production process of industrial pure titanium pipe, pickling is a very important process, which can not be ignored. In the process of hot working or heat treatment, titanium tube will react with oxygen and other gases in furnace gas without protective atmosphere to form oxide layer. The oxide layer formed on the surface of titanium tube is very harmful to the process after pickling and the quality of the final product. For example, if titanium tube is rolled with oxide layer, the tube will have defects. At the same time, due to the existence of oxide layer, the oxide layer will be pressed into the tube surface, resulting in unsatisfactory surface. It directly affects the quality of titanium tube products, material consumption, productivity and economic benefits.

As we all know, acid pickling is the process of removing the oxide layer on the surface of metals by treatment in acid, alkali, salt and their solution. There are many ways to remove oxide layer, the traditional way is to use inorganic strong acid, such as H2SO4 sulfuric acid, hydrochloric acid (HCI), nitric acid (HNO3) and hydrofluoric acid (HF). This kind of method uses the chemical reaction between oxide layer and acid to remove oxide layer. For different materials, one of them can be used according to their performance characteristics.

Among the oxide layers of industrial pure titanium tubes, titanium dioxide (TiO2) is the main one, followed by many low-cost titanium oxides, such as TiO, Ti2O3, TiO2. In addition, there are also high valence oxides of titanium, such as TiO2. The results show that the protective oxide layer is formed on the surface of titanium tube when it is pickled in dilute sulfuric acid wash solution of < 5% at room temperature, which can protect titanium from further erosion by dilute sulfuric acid, but the pickling reaction with titanium is obvious in sulfuric acid of > 5%. At room temperature, the corrosion rate of about 40% sulfuric acid to titanium is the fastest. Hydrochloric acid with concentration less than 5% does not react with titanium at room temperature. When the temperature increases, even dilute hydrochloric acid will corrode titanium, but hydrochloric acid with concentration more than 10% at 70 ℃ and hydrochloric acid with concentration of 1% at 100 ℃ will corrode titanium obviously. However, when there is oxide layer or metal ion (such as copper, etc.) in hydrochloric acid solution, the corrosion effect of hydrochloric acid on titanium can be reduced. Hydrofluoric acid (HF) is the strongest solvent for titanium. Even if the concentration of hydrofluoric acid is 1%, it can react violently with titanium.

  • 2Ti + 6HF = 2TiF3 + 3H2

When there are metal ions such as iron and copper in hydrofluoric acid solution, the dissolution of titanium can be accelerated.

Titanium tube with rough surface is most likely to react with hot and cold dilute nitric acid (HNO3):
  • 3Ti + 4HNO3 + 4H2O = 3H4TiO4+ 4NO
  • 3Ti + 4HNO3 + H2O = 3H2TiO3 + 4NO

In view of the corrosion characteristics of various acids on titanium pipe, in order to effectively remove the oxide layer on the surface of titanium pipe, the pickling of titanium pipe adopts nitric acid and hydrofluoric acid, and its formula and process are as follows:

The solution concentration ratio is:
  • (35 %~40 %) HNO3  +  (5 %~7 %) HF + Remaining H2O 

The solution temperature is: 30 ℃~50 ℃.

The test shows that the above formula and process have some shortcomings: first, the reaction of titanium tube entering into the acid solution is too violent, which makes the temperature of the acid solution rise rapidly, and even makes the acid solution boil, which is very easy to cause oxidation and combustion of the titanium tube matrix, thus increasing the loss of the titanium tube matrix; second, the acid solution splashed out in such a violent reaction process, It is quite harmful to the operators; third, the operating environment of the employees is poor and the pollution is too large. In view of the above reasons, the acid and washing formula and process of titanium tube are adjusted as follows:

  • Main components of solution: nitric acid (HNO3) + hydrofluoric acid (HF)

  • The solution concentration ratio is: (25 %~28 %) HNO3  +  (3 %~5 %) HF + Remaining H2O 
  • The solution temperature is: ≤30 ℃ 

  • Pickling time: 10-20 minutes

The results show that the acid pickling condition after adjustment is better, the reaction of titanium tube entering into acid solution is more stable, and the acid pickling loss rate of titanium tube matrix can be reduced by 30% – 50%.

It should be noted that the titanium tube after pickling must be washed and dried. After pickling in acid solution, the titanium tube can remove the oxide layer, but there is a part of residual acid on the surface of titanium tube more or less. If the residual acid is not removed, part of hydrogen will diffuse to the titanium tube matrix due to the chemical action of residual acid, which will reduce the plasticity of titanium tube. At the same time, the existence of residual acid on the surface of titanium tube will cause premature wear of roller and waste products of titanium tube. Therefore, there is no residual acid on the surface of titanium tube after pickling.

The purpose of drying is to drive out the hydrogen atom in the metal lattice in time, so as to avoid the hydrogen embrittlement of titanium tube during rolling and improve the lubrication performance.

Development of rolling process

The production practice shows that different rolling processes for the same steel tube will get different results. Therefore, the reasonable rolling process is the main condition to ensure the high yield and high quality of industrial pure titanium pipe. It is a basic comprehensive technical subject in the production of industrial pure titanium pipe.

In the past, for the products that have not been produced, the process formulation mainly depends on the experience of brother units and reference materials. The experience from the success or failure of production practice is undoubtedly very valuable and reliable. However, its application scope is local, such as rolling mill equipment, strength of other parts, elastic deformation, wear, plastic deformation, estimation of mechanical parameters, etc. For this reason, the rolling process of titanium tube is determined under the conditions of comprehensive performance, characteristics, condition of tube blank, delivery requirement standard of finished product, capacity of rolling mill equipment and production conditions of industrial pure titanium tube.

For φ 76mm × 7mm industrial pure titanium pipe rolled into φ 45mm × 1.2mm finished product, the rolling process is determined as follows:

  • φ76mm x 7mm → φ51mm x 3mm → φ48mm x 2mm → φ45mm x 1. 2mm

It should be noted that when rolling φ 51mm × 3mm industrial pure titanium pipe, MoS2 lubricant should be applied to the inner and outer walls of the raw pipe for lubrication. It is strictly prohibited to use chlorinated paraffin as lubricant to prevent the pipe from reacting with chloride ion due to high temperature during rolling, resulting in corrosion of the pipe matrix.

Heat treatment process

Heat treatment is a processing method different from rolling. It does not change the size and shape of industrial pure titanium pipe, nor damage the titanium pipe, but essentially changes or improves the performance of titanium pipe. That is to say, the industrial pure titanium tube is used for heating, heat preservation and cooling in the solid range, so as to change its structure and obtain the required performance.

In the rolling process of industrial pure titanium pipe, as other steel pipes, there is a basic feature, that is, the rolled pipe will produce the change of shape and size that can not be recovered by itself plastic deformation.

In the process of plastic deformation, the structure and properties of industrial pure titanium tube will also change. The most important one is work hardening, that is, with the increase of deformation degree, the deformation resistance increases, the strength and hardness increase, while the plasticity and toughness decrease, so that the power consumption of titanium tube in cold rolling increases and the rolling amount is limited.

The purpose of heat treatment is to transform and recrystallize the structure of industrial pure titanium pipe, so as to recover its plasticity before rolling, eliminate the residual stress caused by “work hardening” during rolling or uneven heat dissipation during cooling during hot extrusion, and the existence of such residual stress reduces the plasticity of titanium pipe. Or to eliminate the defects of microstructure caused by improper hot extrusion process, so that the rolling can continue. It can be seen that heat treatment is an indispensable and important process in rolling process.

The oxide layer will be produced when the industrial pure titanium tube is annealed in unprotected atmosphere. Its main component is titanium dioxide (TiO2).

The results show that the oxidation of titanium in air is very slow when the temperature is less than 100 ℃, and only the surface is oxidized at 500 ℃. With the increase of temperature, the surface oxide began to dissolve in titanium, and oxygen began to diffuse to the inner lattice of metal. However, at 700 ℃, oxygen did not enter into the inner lattice of metal in large quantities. When the temperature is over 700 ℃, the diffusion of oxygen to the metal accelerates, and titanium begins to react violently with oxygen in the air at high temperature. The thickness of the oxide layer is closely related to the annealing temperature and time, as shown in Table 1.

Table 1 Relationship between thickness of oxide layer and annealing temperature

Annealing temperature / ℃ Color of oxide layer Thickness of oxide layer / mm
<200 Silvery white Extremely thin
-300 Canary yellow Extremely thin
-400 Golden Extremely thin
-500 Blue Extremely thin
-600 Violet 0.005
-700—800 Red gray 0.0067~0.025
-900 Grey 0.03~0.050

The heat treatment of titanium tube usually adopts the chamber furnace cover to pass argon, but the furnace temperature of the chamber annealing furnace is very uneven, and the sealing performance of the cover is poor. Although argon is used for protection, the surface oxidation of titanium tube often occurs. In serious cases, the surface color of titanium tube is red gray or gray, which can be seen from table 1 as relatively thick oxide layer. This has brought some difficulties to pickling. Improper operation will lead to under pickling or over pickling, and the loss of titanium tube matrix will be large; moreover, the consumption of fuel and argon will also be large, resulting in high production cost. Therefore, in order to improve the heat treatment effect of titanium tube and reduce the production cost, the continuous roller hearth furnace is used instead of the chamber furnace heat treatment.

The process is as follows:

The temperature of furnace inlet is 720 ℃; the speed is voltage: 4.5V, time: 40min; the temperature of furnace outlet is 250 ℃; the speed is slow, air cooling.

The test results show that the surface color of titanium tube treated by this furnace type is light yellow after it is discharged from the furnace, gradually changes to golden yellow, and finally becomes light blue, which is easy to be cleaned by pickling.

Although the production of industrial pure titanium pipe is difficult, as long as we know the characteristics of industrial pure titanium pipe, and correctly formulate the relevant processes in the production process, we can produce high-quality industrial pure titanium pipe.

Quality assurance of titanium pipe

At www.titaniuminfogroup.com, we strive to be the market leader in titanium production through our dedication to control and quality. We have invested heavily in governance and training.

We have invested in advanced equipment & advanced technology, including our own ERP management & QC system.

Each of our product orders undergoes extensive quality control and each comes with an independent third party testing and inspection report.

We have a large inventory stock to be able to satisfy order quickly and on time.

Problems and solutions in titanium tube processing

Defect name

Causes

Ways to
prevent or eliminate

Transverse
scratch on external surface

1. hole
opening is insuf
ficient.

2. the
location of the Ma Tai plate is incorrect.

3. the hole
opening is not smooth or the flange is too sharp.

1. increase
the opening degree of groove.

2., adjust the
location of the market.

3. repair
opening flange.

Longitudinal
scratches on external surfaces

1. the roll of
multi roll mill is not flexible.

2. roll and
pass asymmetry.

3. the outlet
is not smooth.

1. adjust
rolling mill, repair copper tile, adjust balance spring;

2. adjust the
pass;

3. repair
outlet.

Pipe end
cracking

1. the
plasticity of the metal is poor.

2. pass
through hole.

3. excessive
air reduction;

4. there are
serious defects in both ends of the billet.

5. the
clearance of the roll is too large.

1. reduce the
amount of deformation;

2. reduce hole
opening.

3. reduce the
null value.

4. remove the
defects of the tube billets to ensure that the ends are neat.

5. replace
roller bearings and adjust clearance.

The external
ellipticity is too large.

1. pipes do
not rotate.

2. the
finishing section of the pass or slipway is too short.

3. roll and
pass asymmetry.

4. roll and
pass wear seriously.

5. the
diameter of the roll bottom groove is different.

6. the height
of several slideways is inconsistent, or the position of adjusting the
diagonal iron is different.

1. adjust the
feeding mechanism;

2. increase
the length of finishing section.

3. replace or
adjust the pass;

4. replace the
roll and choose the same roll with the same diameter.

5. replace the
slideway and adjust the position of the diagonal iron, so that the positions
of the skew iron of each block are the same.

The outer
surface is rough and not smooth.

1. lubricants
are not suitable or lubricants are not clean.

2. the
clearance is too large.

3. pass and
roll sticky metal;

4. pass and
roll surface rough.

5. excessive
delivery.

1. replace
lubricants and keep lubricants clean.

2. adjust the
rolling mill and reduce the clearance.

3. repair or
replace pass and roll;

4. reduce
delivery.

Internal
surface abrasion

1. the surface of cores is sticky or defective.

2. the inner
surface of pipes is poorly lubricated.

3. the
adjustment of rolling mill is unreasonable.

1. repair or
replace the core;

2. strengthen
inner surface lubrication;

3. adjusting
rolling mill.

Inner surface
pit

1. the inner
surface of the billet is not clean.

2. the
location of the Ma Tai disk is incorrect, causing a string movement.

3. lubricants
are not clean.

4. slipway or
pass curve is not appropriate, causing local deformation too large and the
bonding core.

1. clean the
inner surface of the billet.

2. strengthen
inner surface lubrication;

3., adjust the
location of the market.

4. improvement
of slideway or pass curve design.

Ring
indentation

1. the opening
of the roll pass is not proper.

2. core
position is too close.

1. repair hole
opening;

2. adjust the
position of the core.

Uneven wall
thickness on the same cross section

1. the
deviation of tube wall thickness is too large.

2. the
rotation angle of the pipe is not suitable.

3. the pre
finishing section of the pass or slipway is too short.

4. the rolling
center line is not correct.

5. core or
guide rod bending;

6. the height
of the slideway is different, or the diameter of the roll neck is different.

1. improve the
quality of billet.

2. adjust the
rotation angle;

3. increase
the length of pre finishing section;

4. adjust the
rolling center line;

5. replace the
core or guide bar.

6. replace
slideway or roll (multi roll mill)

Dimension
overshoot

1. the
size of the core is incorrect or the position is not accurate.

2. the
clearance is too large or the pass wear is serious.

3. tool
manufacturing error.

1. adjust
clearance.

2. replace
Tools.

Surface crack

1. the quality
of billets is not good.

2. excessive
variation.

3. inadequate
annealing or uneven annealing temperature.

1. repair and
inspect the tube billet seriously and improve the quality of the billet.

2. reduce
deformation.

3. re
annealing.

Metal or
non-metal pressing in

1. the end of
the tube blank has a puncture.

2. there is
metal on the pass, roll and core.

3. lubricants
are not clean.

4. inner and
outer surfaces of tube billets are not clean.

1. remove pipe
burrs;

2. regular
inspection and repair tools;

3. replace
lubricants;

4. scrub the
inner and outer surfaces of pipes.

Wave

1. excessive
delivery.

2. the length
of the back cone is too short or the taper is too small.

3. the hole
finishing section is worn to cone type.

4. variant
size is too large and finishing section is too short.

1. reduce
delivery;

2. increase
the length or taper of the inverted cone after slideway.

3. replace the
pass;

4. improving
the pass design.

Flex press in

1. the opening
of the pass is too small.

2. part of the
pass wear is serious.

3. excessive
delivery or uneven delivery.

4. gap is not
suitable.

5. pipes do
not turn.

1. enlarging
hole opening.

2. replace the
pass;

3. adjust the
sending organization;

4. adjust
clearance.

5. adjusting
slewing mechanism.

Manual welding technology of titanium pipe

Titanium alloy has the characteristics of low density, high strength and corrosion resistance. As a new material, titanium alloy pipe is widely used in the field of aerospace, and the proportion of titanium pipe in Aeroengine pipeline is increasing. In addition, titanium alloy is a very active metal. It has great affinity for oxygen, hydrogen, nitrogen and other gases at high temperature, and has strong ability to absorb and dissolve gases. Especially in the welding process, this ability is particularly strong with the increase of welding temperature. During welding, it is necessary to control the absorption and dissolution of oxygen, hydrogen, nitrogen and other gases to avoid product scrapping, This brings great difficulties to the welding of titanium alloy pipe.

Manual argon arc welding of titanium pipe

Weldability of titanium pipe

(1) Embrittlement of welded joints
At room temperature, titanium reacts with oxygen to form a dense oxide film, which makes it have good chemical stability and corrosion resistance. At high temperature, especially in the welding process, the reaction speed of titanium alloy with oxygen, hydrogen and nitrogen is very fast. When harmful gases such as oxygen, hydrogen and nitrogen are invaded into the molten pool, the plasticity, toughness and surface color of the welded joint change obviously. Especially above 882 ℃, the grain growth tendency of the joint is serious, and martensite structure is formed during cooling, resulting in the strength, hardness The plasticity and toughness decrease, the overheating tendency is serious, and the joint is seriously embrittled. Therefore, during titanium alloy welding, comprehensive and reliable gas protection should be carried out for the molten pool, droplets and high-temperature area, whether on the front or back.
(2) Stomata
Porosity is the most common defect in titanium and titanium alloy welding, which mainly occurs near the fusion line. Hydrogen is the main reason for the formation of pores. During welding, titanium has a strong ability to absorb hydrogen (stronger at high temperature), but the solubility decreases significantly with the decrease of temperature. Therefore, the hydrogen dissolved in liquid metal often accumulates near the fusion line before it can escape to form pores.
(3) Delayed crack near crack
Titanium alloy is prone to crack (delayed crack) in the near seam area for a period of time after welding. The reason is that hydrogen diffuses from the high-temperature molten pool to the low-temperature heat affected zone. With the increase of hydrogen content, the amount of TiH2 precipitated increases, which increases the brittleness of the heat affected zone. In addition, the microstructure stress generated by the volume expansion of precipitated hydride finally leads to cracks.

Welding requirements and precautions of titanium pipe

  • (1) A special welding workshop shall be set as far as possible. Smoking is strictly prohibited in the room. The environment shall be kept clean and dry, and the convection of air shall be strictly controlled.
  • (2) Welders shall wear clean work clothes and degreasing gloves during welding. It is strictly prohibited to touch parts with bare hands.
  • (3) The welding area and welding wire surface shall be degreased with acetone.
  • (4) High purity argon shall be used for protection, and the purity shall not be less than 99.99%. The air supply flow during welding shall protect the front and back of the weld bead according to the value specified in the process specification.
  • (5) During the welding process, the argon flow in the pipe and the argon flow in the welding tool nozzle shall be kept constant to prevent the convex concave phenomenon of weld pool forming in the pipe.
  • (6) Short arc welding shall be adopted as far as possible and small welding line energy shall be adopted.
  • (7) When spot welding the nozzle, the gap shall be less than 30% of the wall thickness. Each weld shall be welded at one time as far as possible.
  • (8) During welding, the welding tool shall not swing left and right, and the melting end of the welding wire shall not move out of the gas protection zone. During arc striking, air shall be supplied for 10-15s in advance. During arc stopping, the welding gun cannot be lifted immediately. Air supply shall be delayed for 15-30s until the temperature drops below 250 ℃.

Welding technology 

1. Cleaning before welding.
The occurrence of welding defects is closely related to the surface cleanliness of weldments and welding wires. Before welding, the oil stain, water, oxide film and other dirt within 15 ~ 20mm of the edge of the pipe joint and the surface of the welding wire shall be cleaned. The cleaning method can be chemical (pickling) or mechanical (stainless steel brushing) to remove the surface oxide scale. Before welding, it shall also be scrubbed with acetone or alcohol. The cleaned weldment must be welded within 24h, otherwise it needs to be cleaned again. The welding wire shall be subject to vacuum dehydrogenation treatment after pickling, and degreased with acetone before welding.
Gas protection. When welding titanium pipe joints, in order to prevent the welded joints from being polluted by harmful gases and elements at high temperature, necessary argon protection must be provided for the welds, and the purity shall not be less than 99.99%. Argon flow is shown in table 2-1.
2. Selection of welding process parameters.

  • (1) Selection of welding wire. The grade of filler wire shall be selected according to the base metal. Generally, the principle of homogeneity with the base metal is adopted. Sometimes, in order to improve the plasticity of the joint, the welding wire with a slightly lower alloying degree than the base metal can also be selected. The diameter of welding wire shall be selected according to the thickness of base metal, as shown in table 2-1.
  • (2) Selection of power supply and polarity. Titanium and titanium alloy welding generally adopts DC manual tungsten argon arc power supply, and its polarity connection method adopts DC positive connection.
  • (3) Selection of tungsten electrode. The diameter of tungsten electrode shall be selected according to the wall thickness of titanium alloy pipe, generally between 1.0-3.0mm, and the tungsten electrode shall be ground into a cone of 25 ° ~ 45 °.

Installation of titanium pipe

After the arrival of titanium pipes, the owner, construction director, constructors, quality inspectors and welding technicians shall be arranged to inspect the material, standard, quantity, quality and quality certificates of pipe valves. It is necessary to have the factory certificate and quality certificate of the manufacturer. Moreover, the outer diameter and wall thickness shall be measured one by one, and its outer diameter, wall thickness and ovality must meet the specification requirements. The internal and external surfaces shall be lubricated and clean without pinholes, cracks, folds, excessive corrosion and other defects.
Titanium pipes shall be placed equally during transportation. Nylon or synthetic fiber sling should be selected during hoisting. If steel wire rope and shackle are selected, they shall not be in direct contact with the pipeline, and rubber or asbestos products shall be selected for isolation.
For the titanium pipe with good material, if the diameter is small, it is best to get on the bed and make the groove. The speed of the lathe should be slow and pay attention to cooling. For larger diameter (above DN100), a grinder should be used to grind the groove. The operation speed should be slow, complete in several times, and pay attention to cooling. When approaching the requirements, remove the contaminated layer with a fine tooth file until the groove requirements are met. The groove surface shall be flat without crack and double skin, and the burr, slag and oxide shall be completely removed. The groove angle shall meet the welding process requirements. After the groove is processed, pickling and finishing shall be carried out within 50mm on both sides of the groove. Then seal it with plastic cloth and mark it. When grinding and cutting is selected, the operation shall be carried out in other places that meet the requirements. After the groove processing meets the requirements, it shall be moved to the special place for prefabrication.
In the construction of titanium pipe, some small holes such as condensate drainage, drainage and external source taking parts are often encountered, which is difficult to open with conventional methods. Before welding the titanium pipe, draw the size of the hole and the specific and accurate position of the hole on the corresponding titanium pipe. Use a lathe to drill many small holes along the marginal center line of the hole. The denser the better. After all the holes are drilled, tap the central arc plate of the hole with a copper hammer to separate it, and then process the hole to meet the requirements with special tools such as fine tooth round file.
Impurities such as oil stain and oxide film on the surface of titanium pipe will pose a hazard to welding. It is necessary to sort them out before welding. All welding surfaces and the surface of base metal on each side of weldment shall be cleaned with non induced steel wire brush within at least 50nrn. The surface of titanium pipe with oxide layer shall be cleaned of oxide film, and then the base metal shall be cleaned with acetone. It is also necessary to arrange the welding wires in the same way. The processed weldments and welding wires shall be assembled and welded immediately. If the storage time exceeds 2h, the above process must be repeated. It is necessary for the operators to wear clean gloves during the welding process. The welding environment should be clean and the wind direction and wind force should be appropriate to reduce the dust in the air, so as to protect the cleaning of both sides of the groove and the welding wire.
Matters needing attention:

  • 1. Titanium and titanium alloy pipes shall be cut by mechanical method, and the cutting speed shall be low; Special grinding wheel shall be used when cutting or grinding titanium pipe with grinding wheel; Flame cutting shall not be used. The groove should be machined by mechanical method.
  • 2. Inert gas shielded welding or vacuum welding shall be adopted for the welding of titanium alloy pipe, oxygen acetylene welding or carbon dioxide gas shielded welding shall not be adopted, and ordinary manual arc welding shall not be adopted.
  • 3. When installing titanium and titanium alloy pipes, iron tools and materials shall not be used for knocking and extrusion; Rubber plate or soft plastic plate shall be padded between carbon steel supports and hangers and titanium and titanium alloy pipes to prevent them from direct contact with titanium and titanium alloy pipes; When titanium and titanium alloy pipes pass through the wall and floor, they shall be equipped with sleeves, the gap shall not be less than 10mm, and filled with insulating materials, which shall not contain iron impurities.
  • 4. Titanium and titanium alloy pipes should not be directly welded with other metal pipes. When connection is required, looper flange connection can be used. The non-metallic gasket used is generally rubber gasket or plastic gasket, and the chloride ion content shall not exceed 25ppm.

Source: China Titanium Pipe Manufacturer: www.titaniuminfogroup.com

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