中华人民共和国国家标准
National Standard of the People?s Republic of China
UDC 669.14-462
:665
.53.092
GB 9948 - 88
石油裂化用无缝钢管
Seamless steel tubes for petroleum cracking
——————————————————————————————————————————
1. Topic Content and Applicable Scope
This Standard specifies size, profile, technical requirements, test method, inspection rules, packing, marks and quality certificate of seamless steel tubes for petroleum cracking.
This Standard applies to seamless steel tubes for furnaces, heat exchangers and piping in petroleum refineries.
2. Cited Standards
GB 222 Method for Sampling the Test Sample for Chemical Analysis of Steel and Allowable Deviation for Chemical Composition of Final Products
GB 223 Method for Chemical Analysis of Steel and Alloy
GB 228 Metal Tensile Test Method
GB 229 Metal Charpy( U- notch) Impact Test Method
GB 231 Metral Brinell’s Hardness Test Method
GB 241 Metal Tube Hydraulic Test Method
GB 242 Metal Tube Opening Expansion Test Method
GB 246 Metal Tube Press-flat Test Method
GB 2102 General Rules for Inspection and Acceptance,Ppacking, Marks and Quality Certificate for Steel Tubes
GB 2106 Metal Charpy (V- notch) Impact Test Method
GB 5311 Tube Blank of Seamless Steel Tube for High Pressure Boilers
GB 5777 Ultrasonic Testing Method for Seamless Steel Tubes
GB 6397 Test Sample for Metal Tensile Test
GB 7735 Method for Eddy Testing of Steel Tubes
GB 8163 Seamless Steel Tubes for Delivering Fluid
3. Size and Profile
3.1 Outer diameter and wall thickness
3.1.1 The outer diameter and wall thickness of furnace tubes and heat exchanger tubes shall meet what specified in Table 1. The outer diameter and wall thickness of tubes of piping shall meet what specified in GB 8163.
As requested by the demander and agreed by the supplier and the demander, steel tubes of other outer diameter and wall thickness may be supplied.
Table 1
|
Nominal OD，mm |
Nominal wall thickness, mm |
|
1 |
1.5 |
2 |
2.5 |
3 |
3.5 |
4 |
5 |
6 |
8 |
10 |
12 |
14 |
16 |
18 |
20 |
|
Theoretical weight, Kg/m |
|
10 |
0.222 |
0.314 |
0.395 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
14 |
0.321 |
0.462 |
0.592 |
0.709 |
|
|
|
|
|
|
|
|
|
|
|
|
|
18 |
|
|
0.789 |
0.956 |
|
|
|
|
|
|
|
|
|
|
|
|
|
19 |
|
|
0.838 |
1.02 |
|
|
|
|
|
|
|
|
|
|
|
|
|
25 |
|
|
1.13 |
1.39 |
1.63 |
|
|
|
|
|
|
|
|
|
|
|
|
32 |
|
|
|
1.82 |
2.15 |
2.46 |
2.76 |
|
|
|
|
|
|
|
|
|
|
38 |
|
|
|
|
2.59 |
2.98 |
3.35 |
|
|
|
|
|
|
|
|
|
|
45 |
|
|
|
|
3.11 |
3.58 |
4.04 |
4.93 |
|
|
|
|
|
|
|
|
|
57 |
|
|
|
|
|
|
5.23 |
6.41 |
7.55 |
|
|
|
|
|
|
|
|
60 |
|
|
|
|
|
|
5.52 |
6.78 |
7.99 |
10.26 |
12.33 |
|
|
|
|
|
|
83 |
|
|
|
|
|
|
|
|
11.39 |
14.80 |
18.00 |
21.01 |
|
|
|
|
|
89 |
|
|
|
|
|
|
|
|
12.28 |
15.98 |
19.48 |
22.79 |
|
|
|
|
|
102 |
|
|
|
|
|
|
|
|
14.20 |
18.54 |
22.69 |
26.63 |
|
|
|
|
|
114 |
|
|
|
|
|
|
|
|
15.98 |
20.91 |
25.65 |
30.18 |
34.52 |
38.67 |
|
|
|
127 |
|
|
|
|
|
|
|
|
17.90 |
23.48 |
28.85 |
34.03 |
39.01 |
43.80 |
|
|
|
141 |
|
|
|
|
|
|
|
|
19.97 |
26.24 |
32.30 |
38.17 |
43.85 |
49.32 |
|
|
|
152 |
|
|
|
|
|
|
|
|
21.60 |
28.41 |
35.02 |
41.43 |
47.64 |
53.66 |
|
|
|
159 |
|
|
|
|
|
|
|
|
22.64 |
29.79 |
36.74 |
43.50 |
50.06 |
56.42 |
|
|
|
168 |
|
|
|
|
|
|
|
|
23.97 |
31.56 |
38.96 |
46.16 |
53.17 |
59.97 |
|
|
|
219 |
|
|
|
|
|
|
|
|
31.52 |
41.63 |
51.54 |
61.26 |
70.77 |
80.10 |
|
|
|
273 |
|
|
|
|
|
|
|
|
|
|
|
77.24 |
89.42 |
101.40 |
113.19 |
124.78 |
3.1.2 Allowable deviation for OD and wall thickness shall meet what specified in Table 2.
Table 2
|
Type of steel tube |
Size of steel tube |
Allowable deviation |
|
Hot rolled tube |
OD |
≤159
>159 |
±1.00%
±1.25% |
|
Wall thickness |
≤20
>20 |
±12.5%
±10.0% |
|
Cold drawn (rolled) tube |
OD |
≤30
30~50
>50 |
±0.20
±0.30
±0.8% |
|
Wall thickness |
≤3
>3 |
+12
-10
±10% |
Notes: The deviation for size of heat expanded tubes shall be agreed by two parties of the supplier and the demander.
As requested by the demander and agreed by two parties, steel tubes more strict than deviations specified in Table 2 may be produced and the deviations shall be specified in the contract.
3.2 Length
3.2.2 General length of steel tubes
Hot rolled (expanded) tubes: 4 ~ 12m;
Cold drawn (rolled) tubes: 3 ~ 10.5m.
3.2.2 Fixed-rule length and multiple-rule length of steel tubes
The fixed-rule length and the multiple-rule length of steel tubes shall be within the range of usual length. The allowable deviation for total length shall be mm. For each multiple-rule length, allowance for cutting shall be provided in accordance with following stipulations:
OD≤159mm, 5 ~ 10mm;
OD > 159mm, 10 ~ 15mm.
3.3 Degree of bend
The degree of bend of steel tubes shall not exceed what specified below:
Wall thickness ≤ 15mm: 1.5mm/m;
Wall thickness > 15mm: 2.0mm/m
3.4 Profile of end
Both ends of steel tubes shall be right angle cut and spur shall be removed.
3.5 Ellipticity and unevenness of wall thickness
As requested by the demander, agreed by both parties and specified in the contract, the ellipticity of steel tubes and the unevenness of wall thickness shall not exceed 80% of allowance of OD and wall thickness respectively.
3.6 Delivery weight
Steel tubes shall be delivered as per actual weight. It may also be delivered as per theoretic weight. For theoretic weight of best quality carbon steel tubes and alloy steel tubes, see Table 1. The theoretic weight of austenite stainless steel tube is 1.015 of theoretic weight in Table 1. The theoretic weight of martensite stainless steel tube is 0.985 of theoretic weight in Table 1.
The theoretic weight in Table 1 is calculated as per following formula:
Theoretic weight of one steel tube per meter (as density of steel is 7.85g/cm3) shall be calculated according to formula (1):
W = 0.02466 s (D - s) ------------------------------------------(1)
In which:
W ------ Theoretic weight of steel tube per meter, kg;
s ------ Nominal wall thickness of steel tube, mm;
D ------ Nominal OD of steel tube, mm.
3.7 Examples of marks
For steel tubes made of 20# steel, with OD of 89mm and wall thickness of 6.0mm:
a. Hot rolled (expanded) steel tube with length of 6000mm multiple-rule:
Steel tube 20 – 89 x 6.0 x 6000 multiple– GB 9948 - 88
b. Cold drawn (rolled) steel tube with length of 8000mm fixed-rule:
Drawn steel tube 20 – 89 x 6.0 x 8000 – GB 9948 – 88
4. Technical Requirements
4.1 Method of manufacture
4.1.1 Method of steel smelting
Best quality carbon steel 10, 20, alloy steel 12 CrMo, 15 CrMo shall be made in Martin furnace, pure oxygen top blow converter or electric furnace.
Stainless steel 1Cr19Ni9, 1Cr19NiNb, heat resistance steel 1Cr2Mo, 1Cr5Mo shall be smelted in electric furnaces plus fine smelted out of furnace or manufactured with slag heavy melting.
As agreed by both parties, other smelting processes may also be used to produce steel.
In case the demander assigns one process for smelting, it shall be specified in the contract.
4.1.2 Chemical composition of tube blank of steel tubes.
The chemical composition of tube blank of steel tubes shall meet what specified in Table 3 and other specifications shall meet what specified in GB 5311.
4.1.3 Manufacturing of steel tubes
Steel tubes shall be manufactured by using seamless method of hot rolling (expanding) or cold drawn. In case the demander assigns a method to manufacture the steel tubes, it shall be specified in the contract.
4.2 Brand number and chemical composition of steel tubes
4.2.1 The band number and chemical composition (smelting analysis) of steel tubes shall meet what specified in Table 3.
4.2.2 In case chemical analysis is requested by the demander, it shall be specified in the contract. The allowable deviation for chemical composition of final products of steel tubes shall meet relevant stipulations in GB 222.
Table 3
|
Sequence number |
Type of steel
|
Steel number |
Chemical composition, % |
|
C |
Mn |
Si |
Cr |
Mo |
Ni |
Nb + Ta |
S |
P |
|
Not more than |
|
1 |
Best quality carbon steel |
10 |
0.07
~0.14 |
0.35
~0.65 |
0.17
~0.37 |
≤0.15 |
— |
≤0.25 |
— |
0.035 |
0.035 |
|
2 |
20 |
0.17
~0.24 |
0.35
~0.65 |
0.17
~0.37 |
≤0.25 |
— |
≤0.25 |
— |
0.035 |
0.035 |
|
3 |
Alloy steel |
12CrMo |
0.08
~0.15 |
0.40
~0.70 |
0.17
~0.37 |
0.40
~0.70 |
0.40
~0.55 |
≤0.30 |
— |
0.035 |
0.035 |
|
4 |
15CrMo |
0.12
~0.18 |
0.40
~0.70 |
0.17
~0.37 |
0.80
~1.10 |
0.40
~0.55 |
≤0.30 |
— |
0.035 |
0.035 |
|
5 |
Heat resistance steel |
1Cr2Mo |
≤0.15 |
0.30
~0.60 |
0.50
~1.00 |
2.15
~2.85 |
0.45
~0.65 |
— |
— |
0.030 |
0.035 |
|
6 |
1Cr5Mo |
≤0.15 |
≤0.60 |
≤0.50 |
4.00
~6.00 |
0.45
~0.60 |
≤0.60 |
— |
0.030 |
0.035 |
|
7 |
Stainless steel |
1Cr19Ni9 |
0.04
~0.10 |
≤2.00 |
≤1.00 |
18.00
~20.00 |
— |
8.00
~11.00 |
— |
0.030 |
0.035 |
|
8 |
1Cr19Ni11Nb |
0.04
~0.10 |
≤2.00 |
≤1.00 |
17.00
~20.00 |
— |
9.00
~13.00 |
≥8C%
~1.00% |
0.030 |
0.035 |
Notes: ① Residual copper content shall not be > 0.25%.
② For steel made in pure oxygen top blow converter, the nitrogen content shall not be > 0.008%.
③ For steels of 10 and 20, in case the acid solvable aluminum is not > 0.010%, it shall not be taken as the basis for delivery for the time being, however it shall be noted in quality certificate.
4.3 Delivery status
To secure good general performance, the delivery status of steel tubes shall meet what specified in Table 4.
4.4 Physical performance
The longitudinal physical performance of steel tubes delivered shall meet what specified in Table 4.
Longitudinal impact test shall be made to steel tubes with OD≥57mm and wall thickness ≥14mm.
Table 4
|
Sequence number |
Type of steel |
Steel number |
Physical performance |
Delivery status |
|
Tensile
sb ,
N/mm2 |
Yield point, ss, N/mm2 |
Elongation,δ5, % |
Impact power, Aku, J |
Brinell’s hardness, HB |
|
Not less than |
Not more than |
|
1 |
Best quality carbon steel |
10 |
330~490 |
205 |
24 |
— |
— |
Final rolling for hot rolled tubes, normalization for cold drawn tubes |
|
2 |
20 |
410~550 |
245 |
21 |
39 |
— |
Final rolling for hot rolled tubes, normalization for cold drawn tubes |
|
3 |
Alloy steel |
12CrMo |
410~560 |
205 |
21 |
55 |
156 |
Final rolling plus tempering for hot rolled tubes, normalization plus tempering for cold drawn tubes |
|
4 |
15CrMo |
440~640 |
235 |
21 |
47 |
170 |
Final rolling plus tempering for hot rolled tubes, normalization plus tempering for cold drawn tubes |
|
5 |
Heat resistance steel |
1Cr2Mo |
≥(390) |
（175） |
（22） |
（92） |
（179） |
Final rolling plus tempering for hot rolled tubes, normalization plus tempering for cold drawn tubes |
|
6 |
1Cr5Mo |
≥390 |
195 |
22 |
92 |
187 |
Annealing |
|
7 |
Stainless steel |
1Cr19Ni9 |
≥520 |
205 |
35 |
— |
— |
Solution heat treatment: solution temperature ≥1040℃ |
|
8 |
1Cr19Ni11Nb |
≥520 |
205 |
35 |
— |
— |
Solution heat treatment: solution temperature for hot rolled tubes≥1050℃;solution temperature for cold drawn (rolled)hot rolled tubes≥1095℃ |
Notes: ① It is allowable that the impact power of one sample may be lower than specified
value in Table 4 by 8J, however, the arithmetic mean of 3 samples in one group shall not be < specified value in Table 4.
② In case the wall thickness is >16mm, the yield point is allowable to be lowered by 10 N/mm2.
③ When V notch impact test is made, the impact power shall be filled in the quality certificate, but it shall not be taken as the basis for delivery.
④ The criteria in parentheses shall not be taken as basis for delivery and the inspection data shall be filed in the quality certificate.
4.5 Process performance
4.5.1 Hydraulic test
Hydraulic test shall be made to steel tubes piece by piece. The test pressure shall be calculated according to formula (2). Max. test pressure shall be 20 Mpa and holding time not less than 10 seconds. Under test pressure, steel tubes shall not have any leakage or penetration.
…………………………………………………………（2）
In which:
p ------ Test pressure, Mpa;
s ----- Nominal wall thickness of steel tubes, mm
D ------ Nominal OD of steel tubes, mm;
R ----- Allowable stress, for best quality carbon steel and alloy steel, it shall be 80% of yield point specified in Table 4 while for stainless steel and heat resistance steel, 70% of yield point specified in Table 4.
An eddy test or ultrasonic testing may be done instead of the hydraulic test. In the case the ultrasonic testing is used in stead of hydraulic test, the manual damage to the standard test sample shall be C8.
4.5.2 Press-flat test
A press-flat test shall be done to steel tubes with OD > 22 ~ 400mm. After steel tubes are pressed to be flat, the space （h） between two flat plates shall be calculated in accordance with formula (3):
…………………………………………………………（3）
In which,
h ------ Space between flatted plates, mm
s ------ Nominal wall thickness of steel tubes, mm;
D ------ Nominal OD of steel tubes, mm;
a ------ Unit deformation coefficient. For best quality carbon steel and alloy steel, it shall be 0.08; for hest resistance steel, it shall be 0.07 while for stainless steel, it shall be 0.09. No cracks or cracking opening shall exist in test samples after flat-pressed.
4.5.3 Opening expansion test
An opening expansion test shall be made to best quality carbon steel and stainless steel, with wall thickness ≤8mm and OD≤159mm. As requested by the demander and agreed by two parties, the opening expansion test may also be made to alloy steel and heat resistance steel.
The opening expansion test shall be made in cold status. The taper of the tip shall be either 30°, or 45° or 60°. After the opening is expanded, the test sample shall not have any crack or cracking opening. The expanded value of the OD of the test sample shall meet what specified in Table 5.
Table 5
|
Type of steel |
Expanded value of OD of steel tube, % |
|
ID/OD |
|
≤0.6 |
>0.6~0.8 |
>0.8 |
|
Best quality carbon steel |
10 |
12 |
17 |
|
Alloy steel |
8 |
10 |
15 |
|
Heat resistance steel |
6 |
8 |
10 |
|
Stainless steel |
9 |
15 |
7 |
4.6 Surface quality
4.6.1 No defect of crack, folding, cutting, scar, de-lamination or wrinkle shall be allowable to inside or outside surface of steel tubes. Any of these defects shall be removed. The depth for defect removal shall not exceed minus deviation of wall thickness. The actual wall thickness at the place of defect removal shall not be < allowable minimum value of the wall thickness.
The allowable depth of the straight line in inside or outside surface of steel tubes is as follows:
For cold drawn tubes: ≯4% of wall thickness, maximum depth ≯0.2mm.
For hot rolled tubes: ≯5% of wall thickness, maximum depth ≯0.4mm, however for hot expanded tubes, ≯0.5mm.
Other defects which do not exceed minus deviation of wall thickness are allowable.
4.6.2 Oxidation scale shall be removed from inside and outside surfaces of steel tubes, however thin oxidation layer which does not affect inspection is allowable to exist.
4.7 Non-destructive inspection
Ultrasonic testing shall be made to steel tubes piece by piece. The manual damage of the standard test sample is C8.
5. Test Method
5.1 The size of steel tubes shall be measured piece by piece with a caliper or a micro caliper.
5.2 A visual inspection shall be made piece by piece to inside and outside surfaces of steel tubes.
5.3 All performance tests of steel tubes shall meet what specified in Table 6.
Table 6
|
Sequence No. |
Items to test |
Test method |
Quantity for sampling |
|
1 |
Chemical inspection |
GB 222
GB 223 |
One sample for each furnace |
|
2 |
Tensile test |
GB 6397
GB228 |
One sample respectively taken from two tubes of each batch |
|
3 |
Press-flat test |
GB 246 |
|
4 |
Opening expansion test |
GB 242 |
|
5 |
Hardness test |
GB 231 |
|
6 |
Impact test |
GB 229
GB 2106 |
Three samples respectively taken from two tubes of each batch |
|
7 |
Hydraulic test |
GB 241 |
Piece by piece |
|
8 |
Eddy test |
GB 7735 |
|
9 |
Ultrasonic test |
GB 5777 |
6.Rules for Inspection
6.1 Inspection and acceptance
The inspection and acceptance of steel tubes shall be done by the technical supervision department of the supplier.
6.2 Principle for batching
6.2.1 Steel tubes shall be inspected and accepted as per batches. Steel tubes of same steel number, same furnace number, same specification and same heat treatment process (number of furnace) shall make up one batch. The quantity of steel tubes for each batch shall not exceed what specified below:
OD ≤76mm, wall thickness ≤3mm: 400 pieces;
OD > 351mm: 100 pieces;
Other sizes: 200 pieces.
6.2.2 For other steels, if the quantity is not less than 50% of what above specified, it can be put in one batch. If it is less than 50% of what above specified, it can be put in the batch adjoining to the same steel number, same specification and same furnace number.
6.3 Quantity for sampling
The quantity for sampling of each batch of steel tubes for performance test shall meet what specified in Table 6.
6.4 Re-test and rules for judgement
6.4.1 For preliminary performance test of each batch of steel tubes, even if there is only one sample of which the test result is not qualified, apart from put the unqualified one aside, a re-test with double quantity taken from the same batch shall be made.
6.4.2 For the result of re-test (including any criteria of the test), even if there is only one sample which is not qualified, the whole batch can not be delivered. The steels shall be re-heat treated and it shall be inspected and accepted as new batch. The times for re-heat treatment shall not be more than two.
7. Packing, Marks and Quality Certificate
The packing, marks and quality certificate of steel tubes shall meet what specified in GB 2102.
___________________
Additional Description
This Standard is put forth by the Information Standard Research Institute under the Ministry of Metallurgical Industry.
This Standard is prepared by the Anshan Steel Company.
Key persons for preparation of this Standard are Hao Wenxiu and Zheng Guiyun.
The original standard published by ex-Ministry of Metallurgical Industry YB 237 – 70 Steel Tubes for Petroleum Cracking shall become invalid from the date of implementation of this Standard.
The level class mark of this Standard is GB 9948 – 88 I. |
