GB/T 3091-2001 Welded steel pipes for low pressure fluid transportation
Some standard content:
GB/T30912001
This standard adopts IS05591991 "Carbon Steel Pipe for Sewer" in a non-equivalent manner. This standard is based on the merger of GB/T3091-1993 "Galvanized Welded Steel Pipe for Low-Pressure Fluid Transportation", GB/T3092-1993 "Welded Steel Pipe for Low-Pressure Fluid Transportation" and GB/T14980-1994 "Large Diameter Electric Welded Steel Pipe for Low-Pressure Fluid Transportation", and adds the content of straight seam submerged arc welded steel pipe (mainly proposed by Guangzhou Panyu Zhujiang Steel Pipe Co., Ltd.).
This standard differs from IS0) 559:1991 in technical contents such as outer diameter series, allowable deviation of outer diameter and wall thickness. The following major technical contents of this standard have been modified during this revision: the outer diameter and wall thickness series have been modified, and the outer diameter range has been expanded; the usual length range has been modified, and the resistance welding butt steel pipe has been cancelled; the coefficient of the theoretical weight formula has been modified;
- New grades have been added;
- The agreement clause in the original GB/T 14980-1994 standard, the residual height of the burr in the weld, has been revised; corresponding regulations have also been made for the weld residual height and staggered edge of the submerged arc welded steel pipe. The furnace welding manufacturing method in the original GB/T3092-1993 standard has been cancelled, and the straight seam submerged arc welding manufacturing process has been added. From the date of implementation of this standard, GB/T3091-1993 "Galvanized welded steel pipe for low-pressure fluid delivery", GB/T3092-1993 "Welded steel pipe for low-pressure fluid delivery" and GB/T 14980-1994 "Large diameter electric welded steel pipe for low-pressure fluid delivery" have been replaced. Appendix A and Appendix B of this standard are both appendices of the standard. This standard is proposed by the State Bureau of Metallurgical Industry. This standard is under the jurisdiction of the National Technical Committee for Steel Standardization. The drafting units of this standard are: Linggang Group Jinxi Steel Pipe Co., Ltd., Guangzhou Panyu Zhujiang Steel Pipe Co., Ltd., Shanghai Steel Pipe Co., Ltd., Shanxi Taigang Group Linfen Steel Co., Ltd. Welded Pipe Factory. The main drafters of this standard are Qi Huijuan, Wang Long, Tong Lianxun, Li Junqiang, Zhao Shanyuan, Li Yaping, and Liu Wenliang. 56
1 Scope
National Standard of the People's Republic of China
Welded steel pipe for low pressure liquid delivery
Welded steel pipe for low pressure liquid deliveryGB/T 3091—2001
neqiso 559.1991
GB/T3091—1993
GB/T3092—1993
GB/T 14980—1994
This standard specifies the size, shape, weight, technical requirements, test methods, inspection rules, packaging, marking and quality certificate of straight seam welded steel pipe for low pressure fluid delivery.
This standard applies to straight seam welded steel pipes for low-pressure fluid transportation such as water, sewage, gas, air, heating steam, and other structural purposes. This standard marks the different requirements for electric resistance welded steel pipes and submerged arc welded steel pipes respectively. The unmarked ones are applicable to both electric resistance welded steel pipes and submerged arc welded steel pipes.
2 Referenced standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and the parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T222-1984 Sampling method for chemical analysis of steel and allowable deviation of chemical composition of finished products GB/T 223.5-1997 Chemical analysis methods for steel and alloys - Reduced molybdenum silicate photometric method for determination of acid-soluble silicon content GB/T 223.59-1987 Chemical analysis methods for steel and alloys - Antimony-phosphorus clamp blue photometric method for determination of phosphorus content GB/T 223.62-1988 GB/T 223.63-1988 GB/T 223.68-1997 GB/T 223.69-1997 GB/T 228-1987 GB/T 241 1990 GB/T 244—1997
GB/T246—1997
GB/T 700-1988
GB/T1591—1994
GB/T 2102—1988
GB/T 2651—1989
Methods for chemical analysis of iron, steel and alloy
Determination of phosphorus content by butyl acetate extraction photometric method
Methods for chemical analysis of iron, steel and alloy: Determination of manganese content by sodium (potassium) periodate photometric methodMethods for chemical analysis of iron, steel and alloy
Determination of sulfur content by potassium iodate titration after combustion in a tubular furnaceMethods for chemical analysis of iron, steel and alloy
Determination of carbon content by gas volumetric method after combustion in a tubular furnaceTensile test method for metals
Liquid Test method
Metal pipe
Metal pipe
Bending test method
Compression test method
Metal pipe
Carbon structural steel
Low alloy high-strength structural steel
Acceptance, packaging, marking and quality certificate of steel pipesTensile test method for welded joints
GB/T4336—1984
Photoelectric emission spectrometric analysis method for carbon steel and medium and low alloy steels GB/T 6397--1986
GB/T7735-1995
GB/T11345—1990
3. Order Contents
Metal Tensile Test Specimens
Eddy Current Flaw Detection Method for Steel Pipe
Ultrasonic Flaw Detection Method for Steel Welds and Grades of Flaw Detection Results The contract or order for ordering according to this standard shall include the following contents: a) Standard No.:
People's Republic of China. Approved on September 15, 2001 by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
2002-02-01 Implementation
b) Product Name;
c) Steel Grade;
d) Weight or Quantity;
e) Dimensions and Specifications;
f) Delivery Status;
g) Other Requirements.
4 Dimensions, shape and weight
4.1 Outside diameter and wall thickness
GB/T3091—2001
4.1.1 For steel pipes with a nominal outside diameter not exceeding 168.3 mm, their nominal diameter, nominal outside diameter, nominal wall thickness and theoretical weight shall conform to the requirements of Table 1.
Table 1 Nominal diameter, nominal outer diameter, nominal wall thickness and theoretical weight of steel pipes Ordinary steel pipes
Nominal diameter/mm
Nominal outer diameter/nim
Nominal wall thickness/mm
Theoretical weight/(kg/m）
Thickened steel pipes
Nominal wall thickness/mm
Theoretical weight/(kg/m）
The nominal diameter in Table 1 is the nominal size of the approximate inner diameter, and does not indicate the inner diameter obtained by subtracting two nominal wall thicknesses from the nominal outer diameter. 2 According to the requirements of the purchaser, after agreement between the supply and demand parties and indicated in the contract, steel pipes with sizes other than those specified in Table 1 can be provided. 4.1.2 For steel pipes with a nominal outer diameter greater than 168.3 mm, the nominal outer diameter, nominal wall thickness and theoretical weight shall comply with the requirements of Table 2. 58
21.22|23, 8226.
244. 5123. 72126. 63
170.00182.9
17H.17 151.7
GB/T 3091—2001
Table 2 Nominal outer diameter, nominal wall thickness and theoretical weight of steel pipes Nominal wall original/
Theoretical weight/(kg/m)
75.08181.83
.7218B.62
99.18:110.29
80. 3986.4998.65
110.75122.81
68.88189.7
95.29108.71122. 07 135. 39
Nominal wall thickness/n
Measurement/ko
......
188.17201.24211.26
1205.78220
176.06207.43223.04238.60254.11284.99300.35315.671346.15391.50
1223,78
.73240.13
217561956
231.40272.83
24406989
78.76200.87222.94
1323.51:218,09
3: 93 234. 831260. 67
191.58210.311226.8.
1256.0429
258.26276.33294 .3| | tt | t||807.63324.25
61:E5F| | tt | ||tt ||161.0816416974.75
657-20691
705.20741
Note: According to the requirements of the demander, upon agreement with the supplier and noted in the contract, it can be supplied in Table 2 Steel pipes with sizes other than those specified 42
792.13870.26587.08
GB/T 3091—-2001
4.1.3 The allowable deviations of the outer diameter and wall thickness of steel pipes shall comply with the provisions of Table 3. Table 3 Allowable deviations of old outer diameter and wall thickness of steel
Nominal outer diameter 13/mm
48. 3-D≤168. 3
168.3-D508
Allowable deviation of the outer diameter of the substitute
The outer diameter of the pipe end is allowed to be biased/mm
(within 10mm from the pipe end)
4.1.4 The roundness of the steel pipe should not exceed the nominal outer diameter Taxi 0.75%. 4.2 Length
4.2. 1 Usual length
The usual length of resistance welded (ERW) steel pipe is 4000mm~12000mm. The usual length of submerged arc welded (SAW) steel pipes is 3000mm ~ 12000mm. 4.2.2 Fixed length
The fixed length of the steel pipe should be within the normal length range, and the allowable deviation is + mm. 4.2.3 times the length
wall thickness allowable deviation
The incision remains.
4.3 Curvature
4.3.1 Steel pipes with a nominal outer diameter of no more than 168.3mm shall be straight for use, or the curvature index shall be specified by agreement between the supply and demand parties. 4.3.2 For steel pipes with a nominal outer diameter greater than 168.3mm, the bending degree should not be greater than 0.2% of the total length of the steel pipe. 4.4 Pipe end
The two end faces of the pipe should be perpendicular to the axis of the steel pipe and should have no cut burrs. For steel pipes with an outer diameter greater than 168.3mm, the incision slope should not be greater than 5mm, as shown in Figure 1. According to the requirements of the buyer, upon agreement between the supplier and the buyer, and stated in the contract, the ends of steel pipes with a wall thickness greater than 4mm can be processed with bevels. The bevel angle is 30°+, and the remaining thickness of the pipe end is 1.6mm ± 0.8mm. See Figure 2 with end
4.5 Weight
90 noon 9
4.5.1 Unplated Zinc steel pipes are delivered according to actual weight or theoretical weight. The theoretical weight per meter of ungalvanized steel pipes is calculated according to formula (1) (the density of steel is 7.85 kg/dm2), rounded to the nearest 0.01 kg/ mW -- 0. 024 661 5(D -- $)S
The buried weight per meter of the steel pipe, the unit is ks/m; the nominal outer diameter of the D steel pipe, the unit is mm
s —The nominal wall thickness of the steel pipe, in tmm. (1)
4.5.2 Galvanized steel pipes are delivered by actual weight or by theoretical weight. The theoretical load-bearing capacity per meter of galvanized steel pipe (the density of steel is 7.85kg/dm2) is calculated according to formula (2), rounded to the nearest 0.01kg/m. 60
Where: W-
GB/T 3091--2001
W = c[0.024 661 5(DS)S]
The theoretical weight of meters, in kg/m; the weight coefficient of galvanized steel pipes compared with black pipes, see Table 4: Nominal outer diameter of steel pipes, in mm;
S-...Nominal wall thickness of steel pipes, in units is mm. Table 4
Weight coefficient of galvanized steel pipe
Nominal wall thickness S/mm
coefficient.
Nominal wall original 5/mm
4. 6 Marking example
Made of Q235B boiling steel, the nominal outer diameter is 323.9mm, the nominal wall thickness is 7.0mm, and the length is 12000mm Resistance welded steel pipe, its mark is:
Q235B·F323.9X7.0X12 000 ERW CB/T 3091-2001 Made of Q315B steel, the nominal outer diameter is 1016mm, the nominal wall thickness is 9.0mm, and the length is 12000mm Buried welded steel pipe, its mark is:
Q345B 1 016X9.0X12 000 SAw GB/T 3091 2001 Plated steel pipe made of Q3451 steel with a nominal outer diameter of 88.9mm, a nominal wall thickness of 4.0mm, and a length of 12000mm Zinc resistance welded steel pipe: Its mark is: Q345B·Zn 88.9X4.0×12 000ERWGB/T 3091-20015 Technical requirements
5.1 grade and chemical composition
5.1.1 grade
The grade and chemical composition (smelting analysis) of the steel used for steel pipes should comply with the regulations of Q215A, Q215R, Q235A, Q235B in GB/T700 and Q295A, Q295B, Q345A, Q345B in GB/T1591. Upon agreement between the supplier and the buyer, other mild steels that are easy to weld can also be used.
5.1.2 The chemical composition shall be accepted according to the melting composition. When the buyer requires finished product analysis, it shall be stated in the contract. The allowable deviation of the chemical composition of the finished product should comply with the relevant regulations in GB/T222. 5.2 Manufacturing process
Steel pipes are manufactured by resistance welding or submerged arc welding. 5.3 Delivery status
5.3.1 Steel pipes without galvanizing and pipe end processing shall be delivered in the original manufacturing condition. 5.3.2 Steel pipes with a nominal outer diameter not larger than 323.9mm can be delivered galvanized. 53.3 According to the requirements of the buyer, upon agreement between the supplier and the buyer, and stated in the contract, the pipe end of the steel pipe can be threaded. The thread processing method and acceptance criteria shall be specified in the contract.
5.4 Mechanical properties
5.4.1 The mechanical properties of the steel pipe shall comply with the provisions of Table 5. 5.4.2 For steel pipes made of other grades, the mechanical performance indicators shall be determined through negotiation between the supply and demand parties. 61
Q215A,Q215B
Q235A.Q235B
Q295A,Q29313
Q345A,Q34$B
GB/T3091—2001
Table 5 Mechanical properties of steel pipes
Tensile strength α/MPa
Not less than
Belonging to waist point 6,/MPa
Not less than
1 Steel pipes with a nominal outer diameter less than 114.3mm, and steel pipes with a nominal outer diameter greater than 114.3mm, excluding light yield strength, elongation after break of 8.7%
not less than
D≤168.3
2 , used as a reference for determining yield strength and not as a delivery condition. 5.5 Process performance
5.5.1 Bending test
Electrically welded steel pipes with a nominal outer diameter not larger than 60.3mm shall undergo a bending test. There is no filler during the bending test. The bending radius of the ungalvanized steel pipe is 6 times the nominal outer diameter. The bending radius of the galvanized steel pipe is 8 times the nominal outer diameter. The bending angle is 90°, and the weld is located on the side of the bending direction. There should be no cracks on the specimen after the test. Galvanized steel pipes should not have zinc layer peeling off. 5.5.2 Flattening test
Resistance explosive steel pipes with a nominal outer diameter greater than 60.3mm shall undergo a flattening test. For electric resistance welded steel pipes with a nominal outer diameter not greater than 168.3mm, when the distance between the two pressing plates is 3/4 of the nominal outer diameter of the steel pipe, no cracks should appear in the weld; the distance between the two pressing plates is 3/4 of the nominal outer diameter of the steel pipe. /5, there should be no cracks in other parts other than the weld, and the nominal outer diameter should be greater than 168.For 3mm resistance welded steel pipe, when the distance between the two pressure plates is 2/3 of the nominal outer diameter of the steel pipe, no cracks should appear at the weld. When the distance between the two plates is 1/3 of the nominal outer diameter of the steel pipe, no cracks should appear in other parts other than the weld. 5.5.3 Hydraulic test
Steel pipes should be hydraulically tested one by one. The test pressure should comply with the provisions of Table 6. The pressure stabilization time for steel pipes with a nominal outer diameter of less than 508mm should be no less than 5 and the pressure stabilization time for steel pipes with a nominal outer diameter of not less than 508mm should be no less than 10. Under the test pressure, the steel pipe should not leak. The manufacturer can also use eddy current flaw detection or ultrasonic flaw detection instead of hydraulic test. Eddy current flaw detection of steel pipes shall be carried out in accordance with the relevant provisions of GB/T7735, and the artificial defects (drilling) of the comparison sample shall be Class A; ultrasonic flaw detection shall be carried out in accordance with the relevant provisions of GB/T11345, the inspection level shall be Class A, and the assessment level shall be Class III. Hydraulic test shall be used for arbitration. Table 6 Hydraulic test pressure value
Nominal outer diameter of steel pipe D/i
168. 3D323. 0
323.9-D508
5.6 Surface quality
5.6.1 Weld
5.6.1.1 Burr height of electric resistance welded steel pipe
Test pressure value/MPa
The external burrs of the weld of steel pipe shall be removed, and the remaining height shall not exceed 0.5mm1m. According to the requirements of the purchaser and the agreement between the supply and demand parties, the burrs inside the weld can be removed or flattened, and the remaining height shall not exceed 1.5mm. When the total thickness is not more than 4nm, the scraping groove depth after removing the burrs shall not exceed 0.2mm; when the wall thickness is greater than 1mm, the scraping groove depth shall not exceed 0.4mm. 5.6.1.2 Inner and outer weld reinforcement of submerged arc welded steel pipes 32
GB/T 3091... 2001
When the wall thickness of the steel pipe is not more than 12.5mm, the weld reinforcement exceeding the original surface of the steel pipe shall not be more than 3.(1mm; when the wall thickness of the steel pipe is more than 12.5mm, it shall not be more than 3.5mm. Grinding of the super-high weld reinforcement shall be allowed. 5.6.1.3 Misalignment
For submerged arc welded steel pipes with a wall thickness of not more than 12.5mm, the radial misalignment (misalignment) of the edge of the steel strip at the weld shall not be more than 1.6 mm, for submerged arc welded steel pipes with a wall thickness greater than 12.5mm, the radial misalignment should not be greater than 0.125S. 5.6.2 Repair of weld defects
Repair welding is not allowed for steel pipes with a nominal outer diameter of not more than 168.3mm. For steel pipes with a nominal outer diameter greater than 168.3mm, for defects in the weld, the repair weld should be cleaned before repair welding to meet the welding requirements. The shortest length of the repair weld should not be less than 5mm. The maximum length of the repair weld of the resistance welded steel pipe should not be greater than 150mm, and the repair of each steel pipe should not exceed 3. At 200 from the pipe end, Repair welding is not allowed within mm1. Repair welds should be ground, and the remaining height after grinding should be consistent with the original weld. After repair, the steel pipe should be hydraulically tested in accordance with the provisions of Article 5.5.3. 5.6.3 Surface defects
The inner and outer surfaces of the steel arm should be smooth, and defects such as folding, cracks, delamination, and lap welding are not allowed; other defects that do not exceed the negative deviation of the wall thickness are allowed.
5.7 Butt welding of buried arc-welded steel pipes
When butt welding steel pipes, the welding requirements should be met. The longitudinal welds of the butted steel pipes should be staggered by 50 to 200 mm arc length. The butt welds should be uniform and consistent, and the weld residual height should comply with the provisions of Article 5.6.1.2. Butt steel pipes must be hydraulically tested in accordance with the provisions of Article 5.5.3. 5.8 Galvanized steel pipes
5.8.1 Galvanized by hot-dip galvanizing.
5.8.2 Galvanized steel pipes should be tested for the uniformity of the galvanized layer. Steel The pipe sample should not turn red (copper color) after being immersed in copper sulfate solution for 5 consecutive times. 5.8.3 The inner and outer surfaces of the galvanized steel pipe should have a complete galvanized layer, and there should be no black spots and bubbles that are not plated with zinc. Small rough surfaces and local zinc nodules are allowed.
5.8.4 According to the requirements of the purchaser, after agreement between the supply and demand parties, and indicated in the contract, the weight of the galvanized layer of the galvanized steel pipe can be measured, and the average value should not be less than 500g/m2, but any one of the samples should not be less than 480g/m. 5.8.5 Mechanical properties and process performance tests should be carried out on the steel pipe before galvanizing. 5.9 Other requirements
According to the requirements of the purchaser, after agreement between the supply and demand parties, and indicated in the contract, the steel pipe can be supplied according to one or more of the following additional conditions: adding coating, expansion test, metallographic inspection, increasing hydraulic test pressure value, etc. 6 Test method
6. 1 The size and shape of the steel pipe shall be measured one by one with measuring tools that meet the accuracy requirements. 6.2 The various inspection items and test methods of steel pipes shall comply with the provisions of Table 7. Table 7 Inspection items, test methods and sampling numbers of steel pipes Serial number
Inspection items
Chemical composition
Tensile test
Bending testwww.bzxz.net
Flattening test
Hydraulic test
Test method
GB/T222
GB/T 223
GB/T 1336
GB/T 228
GB/T 6397
GB/T244
GB/T 246
GR/T 241
Number of samples
One for each furnace number
One for each batch
One for each batch
One for each batch
Inspection items
Fluorescence testing
Ultrasonic testing
Surface quality testing
Uniformity test of zinc coating
Weight determination of zinc coating
GB/T 3091—2001
Table 7 (end)
Test method
GB/T 7735
GB/T 11345
Appendix A to this standard
Appendix B to this standard
Number of samples
: Randomly select 2 steel pipes from each batch, and take 1 longitudinal specimen from each batch Randomly select 2 vibration steel pipes from each batch, and take 1 longitudinal specimen from each batch 6.3 The specimens for the tensile test of steel pipes are longitudinal specimens or transverse specimens. The angle between the longitudinal specimen cutting position and the weld is at least 90°, and the angle between the transverse specimen cutting position and the weld is about 180°. It is also called cutting the full-section pipe section specimen. The longitudinal test is used as the guide during the stretching. The weld tensile specimen of the submerged arc welded steel pipe is a transverse specimen. The test method is carried out in accordance with GB/T2651, and the test results shall comply with the provisions of Table 5. 7 Inspection rules
7.1 Inspection and acceptance
The inspection and acceptance of steel pipes shall be carried out by the supplier's technical supervision department. 7.2 Batch rules
Steel pipes shall be inspected and accepted in batches. Each batch shall consist of steel pipes of the same brand, specification and galvanized layer (such as galvanized), and the quantity of each batch shall not exceed the following provisions: D33.7 m
D33.7 mm~60.3 m
D>60.3 mm~168.3 mm
D>168.3 mm~323.9 mm
D323.9 mm
7.3 Sampling quantity
The sampling quantity for steel pipe inspection shall comply with the provisions of Table 7. 7.4 Re-inspection and judgment rules
The re-inspection and judgment rules for steel pipes shall comply with the relevant provisions of GB/T2102. 8 Packaging, marking and quality certificate
8.1 The packaging, marking and quality certificate of steel pipes shall comply with the relevant provisions of GB/T2102. 1000 pieces
750 pieces
500 pieces
200 pieces
100 pieces
8.2 According to the requirements of the buyer, after the agreement between the supplier and the buyer, and indicated in the contract, the steel pipe can be coated on the outer surface. The coating should be smooth, firmly attached and with little dripping.
8.3 According to the requirements of the buyer, after the agreement between the supplier and the buyer, and indicated in the contract, the steel pipe can be equipped with a protective cover at the end. The protective cover is made of plastic or metal.
A1 Preparation of test sample
GB/T30912001
Appendix A
(Standardized Appendix)
Test for uniformity of zinc coating Copper sulfate diffusion method From each batch of galvanized steel pipes to be inspected, select 2 pipe sections of not less than 150 mm in length as test samples. Remove the oil stains on the surface of the test sample first and wipe them clean with a clean soft cloth. A2 Preparation of test solution
The test solution is prepared by dissolving 33 g of crystalline copper sulfate (CuSO.·5H,0) or about 36 g of industrial sulfuric acid in 100 mL of distilled water. Then add the powdered copper hydroxide [Cu(OH); or alkaline copper carbonate [CuCO:-Cu(OH)] and stir to neutralize the free acid. Then let it stand for 24 hours and then filter to clarify. The density of the test solution at 15°C is: 1.170 kg/dm. The amount of copper oxychloride added is about 10 g per 10 L solution. The excess can be determined by its precipitation at the bottom of the container. If alkaline copper carbonate (chemically pure) is added, about 12 g is required for every 10 L solution. If powdered copper oxide (Cu0) is used instead of copper hydroxide, about 8 g is required for every 10 L solution. However, it needs to be filtered after standing for 48 hours. A3 Test container
A3.1 The material of the test container must be insensitive to copper sulfate. A3.2 The internal dimensions of the container must ensure that the sample has a gap of at least 25 mm with any wall of the container after being immersed in the solution. A4 Test operation method
A4. 1 The sample should be immersed in the copper sulfate solution for 5 consecutive times with the cut end facing downward. The length of the sample immersed in the solution should be not less than 100 mm. During the test, the temperature of the sample and the solution should be maintained at 15°C to 21°C and should not be stirred. Each immersion of the sample should last for "min, then take it out and immediately wash it in running water, and use a soft brush to brush off all black sediments, and then use a soft cloth to wipe it. A4.2 Except for the last immersion, the sample should be re-immersed in the solution immediately. A4.3 The same test solution should be discarded after 20 immersions of the sample and cannot be used again. A5 Determination of results
After the sample is immersed for 5 consecutive times as specified, and after the final washing and drying, no red (copper plating) color can appear on the sample base material. However, within 25 mm from the end of the sample and 10 mm from the surface of the solution, the sample should not be red (copper plating) on the base material. Except if there is a red deposit of metallic copper on the part. If the above test shows a red deposit of metallic copper on the sample, its adhesion can be determined by the following methods: gently rub and peel off (scrape with a blunt tool such as the back of a knife); immerse in hydrochloric acid solution (1:10) for 15 minutes and then immediately wash in running clean water. If the zinc layer reappears on the bottom surface, the sample is judged to be qualified.
If there is doubt about whether there is a zinc layer on the bottom surface under the metallic copper red deposit, the metallic copper red deposit can be scraped off and one to several drops of dilute hydrochloric acid can be dripped there. If there is a zinc layer, active hydrogen will be generated. In addition, it can also be determined by a qualitative test of zinc, that is, a small piece of filter paper or a pipette is used to collect the dripping acid solution, and then neutralize it with ammonium hydroxide to make it weakly acidic. Hydrogen sulfide is passed through this solution to see whether a white precipitate (zinc sulfide) is generated to determine whether it is used.
B1 Preparation of sample
GB/T 3091---2001
Appendix B
(Appendix to the standard)
Determination of the amount of zinc coating Antimony chloride method
Take 2 steel pipes from each batch of galvanized steel pipes to be inspected, and cut a pipe section of 30 mm to 60 mm (depending on the size) at one end of each steel pipe (after cutting other samples) as a sample. There should be no rough surface and zinc nodules on the surface of the sample. Clean the surface with a pure solvent such as benzene, petroleum benzene, trichloroethylene or carbon tetrachloride. Rinse with ethanol, rinse with clean water, and apply varnish (benzoic acid) on the end faces of both ends of the sample, and then dry well.
B2 Preparation of test solution
Dissolve 32g of antimony dichloride (ShCl) or 20g of antimony trioxide (Sh,O,) in 1000mL of hydrochloric acid with a density of more than 1.18kg/dm2 to prepare a stock solution. Before the test, 5 mL Add the original solution to 100 ml of hydrochloric acid with a density of 1.18 kz/dm° or more as the test solution. B3 Test operation method
B3.1 Use a large balance to weigh the sample after removing the oil stain, accurate to 0.01g. B3.2 Immerse the weighed sample in the test solution, immerse one sample at a time, and the liquid level must be higher than the sample. During the measurement process, the solution temperature must not be greater than 38 ℃.
B3.3 When the sample is dissolved, the generation of hydrogen becomes very small and the zinc coating has disappeared, take out the sample. Rinse in clean water and wipe with cotton or clean cloth. After drying, weigh it on the balance again, accurate to 0.01g. B3.4 The outer diameter and inner diameter of the sample should be measured once in two mutually perpendicular directions at the - end of the sample after the zinc layer is stripped, and the average value is taken as the actual outer diameter and inner diameter of the steel pipe, accurate to 0.01mm. B3.5 The test wire can be reused as long as the zinc layer can be easily removed. B4 Calculation of test results
The surface area of the sample is calculated by formula (B1):
A = yuan (D - + d) h
Wherein: A-
The surface area of the sample after the zinc layer is stripped, in m: D-the outer diameter of the sample after the zinc layer is stripped, in И; d-the inner diameter of the sample after the zinc layer is stripped, in m! The length of the sample, in m.
The weight of the sample reduced after weighing once is calculated by formula (B2): Am = ml - m2
Wherein: Am
The weight of the sample reduced after weighing once, in g: The weight of the sample before stripping the zinc layer, in g: m:-the weight of the sample after the zinc layer is left, in g. The weight of the galvanized layer is calculated by formula (B3):
Wherein: ma
The weight of the galvanized layer, in g/m\;
The weight of the sample reduced after the second weighing, in area; (B1)
-(B2)
GB/T3091—2001
: The surface area of the sample after the zinc layer is stripped, in average. A.
The thickness of the galvanized layer of the galvanized steel pipe is calculated by formula (B4) (approximate value): e-ma
Wherein: ε--The approximate value of the thickness of the galvanized layer, in μrm#ma--The weight of the galvanized layer, in g/m.+*.-(B4)1 Use a large scale to weigh the sample with the oil stain removed, accurate to 0.01g. B3.2 Immerse the weighed sample into the test solution, one sample at a time, and the liquid level must be higher than the sample. During the measurement process, the solution temperature shall not exceed 38 ℃.
B3.3 When the sample is dissolving, the generation of hydrogen becomes very small, and the zinc coating has disappeared, take out the sample. Rinse in clean water and wipe off with cotton or clean cloth. After drying, weigh it on the balance to the nearest 0.01g. B3.4 The outer diameter and inner diameter of the sample should be measured once in two mutually perpendicular directions at the two ends of the sample after the zinc layer is peeled off, and the average value shall be taken as the actual outer diameter and inner diameter of the steel pipe. Accurately to 0.01mm. The B3.5 test melt line can be reused as long as the zinc layer can be easily removed. B4 Calculation of test results
The surface area of the sample is calculated using formula (B1):
A = yuan (D -+d)h
where: A-||tt| |The surface area of the sample after the zinc layer is peeled off, the unit is m: D - the outer diameter of the sample after the zinc layer is peeled off, the unit is И; d The inner diameter of the sample after the zinc layer is peeled off, the unit is m! The length of the specimen, in m.
The weight of the sample after one drink is weighed is calculated using formula (B2): Am = ml -m2
In the formula: Am
The sample is reduced after one weighing Weight, unit is: the weight of the sample before the zinc layer is peeled off, the unit is g: m: - the weight of the sample after the zinc layer is left, the unit is g. The weight of the galvanized layer is calculated using the formula (B3):
where: ma
The weight of the galvanized layer, in g/m\;
Test after weighing twice The weight loss of the sample, the unit is area; (B1)
-(B2)
GB/T3091-2001
: The surface area of the sample after the zinc layer is peeled off, the unit is " . A.
The galvanized steel pipe thickness is calculated by formula (B4) (approximate value): e-ma
where: ε - the approximate value of the galvanized layer thickness, the unit is μrm# ma--The weight of galvanized layer, unit is g/m +*.-(B4).1 Use a large scale to weigh the sample with the oil stain removed, accurate to 0.01g. B3.2 Immerse the weighed sample into the test solution, one sample at a time, and the liquid level must be higher than the sample. During the measurement process, the solution temperature shall not exceed 38 ℃.
B3.3 When the sample is dissolving, the generation of hydrogen becomes very small, and the zinc coating has disappeared, take out the sample. Rinse in clean water and wipe off with cotton or clean cloth. After drying, weigh it on the balance to the nearest 0.01g. B3.4 The outer diameter and inner diameter of the sample should be measured once in two mutually perpendicular directions at the two ends of the sample after the zinc layer is peeled off, and the average value shall be taken as the actual outer diameter and inner diameter of the steel pipe. Accurately to 0.01mm. The B3.5 test melt line can be reused as long as the zinc layer can be easily removed. B4 Calculation of test results
The surface area of the sample is calculated using formula (B1):
A = yuan (D -+d)h
where: A-||tt| |The surface area of the sample after the zinc layer is peeled off, the unit is m: D - the outer diameter of the sample after the zinc layer is peeled off, the unit is И; d The inner diameter of the sample after the zinc layer is peeled off, the unit is m! The length of the specimen, in m.
The weight of the sample after one drink is weighed is calculated using formula (B2): Am = ml -m2
In the formula: Am
The sample is reduced after one weighing Weight, unit is: the weight of the sample before the zinc layer is peeled off, the unit is g: m: - the weight of the sample after the zinc layer is left, the unit is g. The weight of the galvanized layer is calculated using the formula (B3):
where: ma
The weight of the galvanized layer, in g/m\;
Test after weighing twice The weight loss of the sample, the unit is area; (B1)
-(B2)
GB/T3091-2001
: The surface area of the sample after the zinc layer is peeled off, the unit is " . A.
The galvanized steel pipe thickness is calculated by formula (B4) (approximate value): e-ma
where: ε - the approximate value of the galvanized layer thickness, the unit is μrm# ma--The weight of galvanized layer, unit is g/m +*.-(B4).
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