DE1608181A1 - Use of a nickel steel - Google Patents

Description

DiL-ING. G. EICHENBERG _{4 DöSSELDORF / Wed} October.

DIPL-ING. H. SAUERLAND ceciuenallee ve

DR.-ING. R. KING "~ ™« * «

PATENT LAWYERS

International Nickel limited, Thames House, Millbank,

London, S.W. 1, England

"Using a Uiekelstahla"

The invention "relates to the use of a nickel steel as a material for pressure vessels that are in the Use subject to the action of hydrogen. This applies in particular to pressure vessels in cracking systems, i.e. for pressure vessels in which crude oil is treated with hydrogen gas under pressure at elevated temperature so that hydrogenation takes place simultaneously with the catalytic cracking. In this process, commonly called hydrogenation cracking is known, the pressure of hydrogen is 0.7 to 1.4 kg / mm at a temperature of 315 to 455 ºC. The end product of the aforementioned process is fuel or other high quality distillates.

The conventional pressure vessels for hydrogenation cracking are extremely massive; so are pressure vessels with a length of about 30 m, an inner diameter of 3 m and a wall thickness of 18 em with a total weight of 750 t is by no means uncommon. Such dimensions,

009 ^ 4.6 / 0 25 3 _

BANK ACCOUNT DEUTSCHE BANKAO., DÜSSELDORF 1072161 POST CHECK ACCOUNT i ESSEN 6734

18. OkJt ο .1.9.6.7 .... an .. !!. VeJEWi: ^^^ sheet ....

in particular, the great wall thicknesses not only lead to difficulties in manufacture, but also in transport and installation. The conventional pressure vessels are generally made of a normalized and stress-free annealed steel with low strength and 2.25 ° chromium and 1 $ molybdenum, which is known under the ASTM designation A 587 D. The low strength of this steel, ie its tensile strength of 42 to 56 kg / mm, is the reason for the large wall thickness of the pressure vessels, which is required to cope with the high operating pressures. The object on which the invention is based is now to propose a steel with greater strength which allows the wall thickness and thus the total weight of pressure vessels for hydrogenation cracking to be reduced.

In addition, the steel should maintain its strength at the high process temperatures of hydrogenation cracking, be stable and experience no impairment of its technological properties even after long periods of operation. In addition, the steel must be tough and ductile at both room and operating temperature and sufficient Have resistance to temper brittleness.

After all, a pressure vessel must be used for the aforementioned pressure vessels suitable steel regardless of its structural

6/025?

sheet

ability to resist the attack of hot hydrogen. For this reason, the inner walls of the pressure vessel are generally plated with an austenitic stainless steel for hydrogenation cracking. Steels against the Not resistant to attack by hot hydrogen, bubbles and cracks form despite the plating ο because of the large size Wall thickness of the pressure vessel must plating with the stainless Steel done by applying a welding layer, which is not only expensive but also difficult since plating must be done after the container is completed. If, on the other hand, the pressure vessels are made of high-strength steel, they can have smaller wall thicknesses and the plating layer can be applied by roll cladding.

To avoid the aforementioned difficulties, the use of a 2.25 ° f chromium and 1 $> molybdenum-containing steel in the quenched and tempered condition has been proposed, in which it has a higher strength than in the normalized and annealed tension-free state. The tensile strength of this steel in the quenched and tempered state should be up to about 112 kg / mm. Its notched impact strength, on the other hand, is

1 to 1.2 kgm / cm very low. In addition, the steel owns ■ In this state a bainitic structure, the special one tends to be brittle.

.009846 / 0253

16Ö8181

1.8ο. Oct 19.6.7 ... _αη ..!.! Application of a Iickels.tatil.s !! sheet

The invention is now based on the surprising Finding that certain low carbon steels and nickel, aluminum and molybdenum are preferred as well niobium also have very good technological properties, in particular high strength both at room temperature as well as at elevated temperatures, good toughness and ductility as well as resistance to both hot hydrogen as well as against tempering brittleness and high stability at high temperatures. These steels are therefore particularly suitable as a material for pressure vessels for hydrogenation cracking of petroleum.

According to the invention, therefore, for the above-mentioned purpose, a steel having less than 0.04 & carbon, 5 to 10 $> nickel, 0.7 to 1.2 # aluminum, 0.5 to 2 ⁰ Jo molybdenum, 0 to 1.5 $ Chromium, 0 to 1 ° ß> Manganese, 0 to

1 per cent silicon, 0 to 0.12 $ niobium, 0 to 5 fi cobalt, 0 to

2 $ copper, 0 to 0.01 $ boron and 0 to 0.2 $ tantalum, the remainder including iron impurities from the smelting process. In the proposed steel, the molybdenum content can be completely or partially replaced by tungsten, with two parts by weight of tungsten each replacing one part by weight of molybdenum. However, molybdenum is much more effective than tungsten in terms of the technological properties of steel and is therefore preferable.

009846/0253

Oct 18, 19.61 ... _αη .,! IUse. of a nickel steel.!.! ..... Blatt, SL

Among the impurities in the steel, the contents of nitrogen, oxygen, sulfur and phosphorus should be kept as low as practically possible. The steel does not need to contain elements such as vanadium and titanium, since higher contents of these elements impair its toughness. After all, the steel according to 0.2 ° / o vanadium and titanium can be given by

The carbon content must be below 0.04 f <> and advantageously does not exceed 0.03 ° β> ₀ With higher carbon contents, there is also an increased risk that the nascent hydrogen which occurs during hydrogenation cracking and which penetrates the plating layer will react with the carbon present as carbide . This reaction leads to the formation of methane at the grain boundaries as well as other inhomogeneities. Sometimes the pressure of the resulting gas can rise to such an extent that bubbles or cracks form. A relatively low carbon content does not always prevent these difficulties, since other low carbon steels not falling under the invention were defective in the investigation.

The nickel content of the steel of the invention contributes to adequate hardenability. It is 5 to 7 # and for optimal adhesion 8 to 9 »5 i» »

Aluminum is an effective hardener and yields

009846/0253

Oct 18, 1.S.61 ... απ .1! JMyί§MMM ...... βi.M§ ..... M .. ° k§lM.1ίSül.l.§ .. ^l .! sheet

! "Sheet * £ L

high strengths} yes, too high aluminum contents of "for example 1.5 $ impair the impact resistance to a great extent, so that the aluminum content must not exceed 1.2 $, but is preferably at least 0.75 % .

Molybdenum increases the strength and strengthens the resistance to temper brittleness, so that the molybdenum content is advantageously $ 0.75 to $ 1.5.

Niobium gives the steel high strength without impairing its toughness, provided that its content does not exceed $ 0.12. In addition, it appears that niobium, because of its affinity for carbon and the resulting carbide formation, reduces the risk of cracking because the carbides are less easily attacked by hydrogen. The steel therefore advantageously contains at least 0.008 # niobium.

Steels of the above-mentioned composition, which contain 0.008 to 0.12 » niobium, are new and therefore represent an essential part of the present invention

A particularly preferred steel according to the invention consists of up to 0.03 # carbon, 5 to 9.5 "A nickel, 0.75 to 1.2 ° j> aluminum, 0.75 to 1.5 # molybdenum, 0.008 to 0 , 08 "Jo niobium, 0 to 1 i * chromium, 0 to 0.75 # manganese, 0 to 0.5 ^ silicon, the remainder including melting-related

009846/02 & 3

"Sheet;

! §. · -9.M * "1.967 απ" J. ^e Z ^ .§M ^ S. §Ϊ́ $$$. Iic ^ elsiafels. "Sheet;

Impurities iron. A steel with 0.02 $ carbon, 9 # winding, 1 fi aluminum, 0.9 # molybdenum, 0.06 to 0.1 $ niobium, 0.5 # manganese and 0.2 $ silicon, the remainder, has particularly good properties Iron including impurities from the smelting process.

The invention is explained in more detail below on the basis of exemplary embodiments.

In the course of tests, the "material Steels 1 to 5 suitable for pressure vessels and three comparative steels A, B and C are melted. The compositions These steels, the remainder of which, apart from impurities, consisted of iron, result from the following Table I.

C. Ni Mon
W) T a bell e I. 0 Si
(*) other
elements 0.008 9.05 0.98 0 _ _ stole 0.008 9.15 1.02 Al
(*) Nb Mn
(*) 0 - - 1 0.017 9.27 1.03 1.02 _ _ 0 - - 2 0.020 9.40 1.00 0.96 0.008 - 0 , 05 - 3 0.02 9.10 0.94 1.08 0.008 - , 22 - 4th 0.15 - 0.93 1.07 0.06 0 , 09 , 32 2.28 Cr 5 0.02 0.91 - - 1.0 0.08 0 , 54 , 18 1.47 Cu A. 0.18 2.58 0.60 - 0 , 54 , 16 0.11V
3.00 Cr B. * 0.03 0 , 38 0 0.02 - 0 , 76

* Aluminum was only added to steel B for deoxidation.

0 0 9 84 R / η 2 5 3

Jik .... PM. · ... Jj3.6J7an. "^^^ sheet ..

Steels 4, B and C were melted in air, the rest, however, in a vacuum induction furnace »Aus den Blökken of the test steels were round bars with a diameter of 19 mm or square billets with an edge length of 16 mm forged and then hot rolled; steel 5 became a 12.5 mm thick blank is forged and hot rolled. The steels were then one or more of the following subjected to specified heat treatments:

Heat treatment:

A. 1. Annealing for one hour at 870 ° C, air cooling,

B. 1. Annealing for one hour at 870 ° C, air cooling, 2 * two-hour annealing at 540 ° C, air cooling,

C. 1. Annealing for one hour at 870 ° C, water quenching, 2. annealing for two hours at 540 ° C, air cooling,

D. 1. Anneal for one hour at 870 ° C, air cooling at one of the cooling rates a cooling speed corresponding to a 92 mm thick blank quenched in water, 2 «, three-hour annealing at 510 ° C, air cooling,

E. 1. One hour curing at 565 ° C,

P. 1. Annealing for one hour at 870 ° G, X cooling in a stream of air at a cooling rate corresponding to the cooling of a water-quenched 92 mm blank,
2. Annealing for four hours at 565 ° C, air cooling.

0 Ό Ü UU R / Π 0 S 3 COPY

s ^1. · _B | _att

After the heat treatment, the test steels were mechanically examined at different! temperatures, whereby according to Table II the 0.2 ^ yield point, the tensile strength ^ elongation, constriction and notched impact strength Charpy were determined *.

Table II

warmth
treat
lung Yersuchs-
tempera-
door
( ⁰ C) Stretch
limit ρ
(kg / mnr) Tensile strength
ability ο
(kg / mm) Deh
tion
M. A-
nice
tion Curb "
toughness
ρ
(kgm / cm) stole A.
B.
B. RT
RT *
425 69.5
105.3
73.9 78.4
108.5
80.3 21
21
22nd 80
71
75 31.8
1.81 1 A.
B.
C. RT
RT
425 69.0
105.8
75.7 79.8
109.2
80.9 19th
19.5
23 82.5
70.8
75 31.3
2.94 2 - A.
B.
B.
C. RT
RT
425
425 70.3
107.8
80.6
87.9 87.3
117.8
91.0
95.9 20th
19th
20th
20th 82.5
68.5
75.0
71.5 38.7
8.12 3 B.
B
B. RT
345
455 98.9
79.5
64.0 100.9
83.0
71.0 21
21
25th 76
75
80.8 19.9 4th D.
D.
D. RT
345
455 112.5
102.5
93.1 140.1
125.8
113.9 16.5
18.5
17.0 59.5
65.0
59.8 5.17 5 ♦
# RT
345
455 76.2
70.0
61.9 94.2
104.9.
94.7 18th
17th
19th 63.8
47.2
49.0 2.7 A. B.
E.
E. RT,
345
455 57.9
47.2
38.4 70.1
58.5
47.4 27
23.5
23.5 72.2
59.5
49.0 13.9 B. P.
P.
i ¹ RT
345
455 85.7
71.7
63.4 96.3
. '81.7
.73.6 19.5
17.5
20.5 68.8
60.0
70.2 -13.7 C.

* a stretched and tempered

009846/02

1.8. Oct. 19.67. " _Αη . '! Use a ^^ iric ^^ jstails ^. _sheet

The test results of Table II show that the mechanical properties of steels 1 to 5 at room temperature and elevated temperatures their use as
Material - for hydrogen tanks and the like »make possible. The steel 5 had particularly good properties, namely one
Tensile strength of almost 140.1 kg / mm, a notched impact strength of 5 »17 kgm / cm at room temperature and a tensile strength of over 115 kg / mm at 455 °.

The relatively low notched impact strength
of steels 1 and 2 after heat treatment B at room temperature is due to the low carbon content
of these steels, as a result of which oxide inclusions exerted a harmful influence. However, one can face these difficulties
by using suitable process techniques or setting a higher carbon content, such as
at steel 3, face it. Steel A serves as an example of the well-known steel containing 2.25 tf> chromium and 1 $ molybdenum. Table II shows the strength of this steel
from usually 42 to 56 kg / mm after normalization and stress relief annealing by water quenching and

let, was increased to 94.2 kg / mm, but a
resulted in substantial loss of strength.

From a comparison of the properties of steels 3 and 4 after heat treatment B at room temperature
that an increase in Job salary from $ 0.008 to $ 0.06

009846/0253

.18. Oct. 1.9.62 ... to !! XerweMung a ^ McXe ^ tahl.!. ^1st sheet

to a noticeable. Increase their toughness without a substantial one Loss of strength resulted.

The niobium-containing steel 5 according to the invention and the steels B and C were also examined to their long-term stability, their sensitivity to temper brittleness and determine their hydrogen resistance. The various test conditions to which the steels are subjected are shown in Table III below together with the results obtained during the tests.

009846/0253

.18 .'....- .. OM-0 19.6.7 .... an .. !!. Y.use ...,. One s .... Nickels t ahls « _B | _att

I *.

Table III

Steel condition stretch- tensile- elongation, constriction, notch impact

($) ikit

tenacity ($) runs tenacity

kg / imn) (kg / ^ 2) (?) ²

Normal to
was standing 112.5 140.1 16 , 5 59.5 5 , 19th 500 h
400 ° ö 118.7 139.4 15th 54.0 4th , 32 5000 h
400 ° 0 122.0 139.5 16 , 5 59.8 3 , 80 500 h
455 ⁰ C 118.9 140.6 14th 50.0 4th , 24 50Oh
400 ° 0
π *
2 118.7 139.4 15th 54.0 4th , 32 0.7 kg / mar 455 ° 0 / H ₂ *
0.7 kg / mm ² 118.9 140.6 14th , 5 50.0 4th , 24 B. Normal to
was standing 57.9 70.4. 27 72.5 13th , 9 5000 h
345 ° C 57.5 68.9 24 72 8th , 3 5000 h
455 ° 0 59.9 70.3 25th 69.5 . 5 , 71 1000 h 455 ⁰ O / H ₂ *
0.7 kg / mm ² 46.7 53.9 7th 7th 0 , 17th O Normal to
was standing 85.7 96.3 19th , 5 68.8 13th , 7 5000 h
400 ° 0 100.3 109.3 18th , 5 66.0 3 ,8th 5000 h
455 ° 0 92.2 101.9 16 »5 57th, 8th 0 »52 Overpressure 00 9 8 4 K / 0 7 S3

..1.8. Oct. «, 1.9.6.7 .. _αη ...!. '.. Use. a ^^ nickel steel.!.!. Sheet, ........ £ 51

From Table III it can be seen that the behavior of steel 5 was very satisfactory, as was the case with steels B and C does not apply. Steel B had severe temper brittleness and was despite its low carbon content very sensitive to hydrogen attack. Closer examination of this steel revealed a strong attack on the grain boundaries. Likewise, the steel lost 0 a prolonged annealing at 455 C practically all of its impact resistance.

The steel according to the invention is particularly suitable as a material for manufacturing such pressure vessels, which must have a high resistance to hydrogen, especially for pressure vessels for hydrogenation cracking; however, he is also suitable for other purposes, especially where a relatively high strength and at the same time good Tenacity is required.

The steel can be made into a variety of semi-finished products including blanks, billets, wire and forgings are processed.

009846 / 0.253

Claims (5)

... 1.8.0 Oct .. 1.9.6.7 .. an ... '! .. application .ei.nes .... Nickels..t.alll.§ ..!. ^I. Sheet .Jk- "Ί Ί608181 International Nickel Limited, Thames House, Millbank, London, S.W. 1, England Patent claims: Use of a steel consisting of below 0.04 ° / ° carbon, 5 to 10 fo nickel, $ 0.7 to $ 1.2 aluminum, 0.5 to 2 ° ß> molybdenum, 0 to 1.5 fo chromium, 0 to 1 i> manganese, 0 to 1 ^c / o silicon, 0. to 0.12 <fo niobium, $ 0 to $ 5> cobalt, 0 to 2 <fi copper, $ 0 to $ 0.01> boron, 0 to 0.2 i » tantalum, Remainder iron including smelting pollution-related contamination, as a material for pressure vessels, which are exposed to the attack of hydrogen, in particular pressure vessels for the hydrogenation cracking of petroleum. 2. Use of a steel according to claim 1, the molybdenum content of which, however, has been completely or partially replaced by tungsten, 009846/0253 whereby two parts by weight of tungsten each replace one part by weight of molybdenum, for the purpose according to claim 1o 5. Use of a steel according to claims 1 or 2, but containing 5 "to 7 ° nickel, for the purpose according to claim 1. 4. Use of a steel according to claims 1 or 2, but _{containing 8 to 9 f} 5 i ° .Nickel, for the purpose according to claim 1. 5. Use of a steel according to claims 1 to 4, consisting of below 0.04 1 ° carbon, 5 to 10 <$> nickel, 0.7 to 1.2 io aluminum, 0.5 to 2 io molybdenum, 0.008 to 1.2 1 ° niobium, O until 1, 5 5 O until 1 C.
I. O until 1 t
I. O until 5 C.
I. O until 2 C.
I. O until O, 01 < O until O. 2 < Ίο chrome, fo manganese, & Silicon, fo cobalt, fo copper, % Boron,. i » Tantalum. Remainder including smelting pollution caused by the application of iron, for the purpose according to claim 1 «, .. · '■■ -,' - 009846/0253 For rubbing the ..! § .. 'QM? .. Jß & L cm 6ο Use of a steel according to claim 5, consisting of up to 0.05 ί> carbon, 5 to 9.5 i> Mekel,
$ 0.75 to $ 1.2> aluminum,
0.75 to 1.5 # molybdenum,
$ 0.008 to $ 0.08> Biiobes,
0 to 1 i » chrome,
$ 0 to $ 0.75> Manganese,
0 to 0.5 & silicon, Remainder bisen, including smelting zing-related impurities, for the purpose according to claim 1, 7 · Use of a steel according to claim 5, but which is 0.02 i » carbon, 9 $> nickel, 1? S aluminum, 0.9 # molybdenum, 0.06 to 0.1 $> mob, 0.5 $> Manganese and $ 0.2 silicon, the remainder including impurities caused by the smelting contains iron, for the purpose according to claim 1 · 009846/0253