This standard applies to continuous cast grey cast iron straight pipes for water and gas transportation. The use of cast iron pipes should refer to relevant pipeline design and construction specifications. GB 3422-1982 Continuous Cast Iron Pipes GB3422-1982 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
GB3422-1982
Continuous Cast Iron Pipe
1983-11-01
1982-12-31Approved
National Bureau of Standards
Page 1
1 Classification,
2 Dimensions, shape, weight
3 Technical requirements
4 Test methods
5 Inspection rules
6 Marking, packaging and quality certificate
7 Transportation and storage
Page 2
This standard applies to sand-cast centrifugal cast iron straight pipes for conveying water and gas. The use of cast iron pipes should refer to relevant pipeline design and construction specifications. Area
Page 3
1 Classification
Continuous cast iron pipes are divided into three grades: LA, A and B according to their wall thickness. M||tt ||Page 4
2.1 Size and shape
2 Size, shape, weight
2.1.1 The shape and size of the socket straight pipe shall comply with the provisions of Figure 1 (omitted), Table 1 and Table 2. Nominal diameter
75~450
500~800
900~1200
Nominal diameter
Inside the socket
Table 1 Bearing Mouth size
Dimensions of each part
Page 5
1144.024.2
Wall thickness T,
29.0268.41
1246.025.828.431.0318.51
Table 2 Wall thickness and weight of continuous cast iron pipe
Weight of straight part 1 meter kg
The specific gravity of cast iron is 7.20.
Note: ①When calculating weight,
Effective length L, mm
Total weight, kg
3170345037303880
42304580
Grade A Grade B
878囍
43004660www.bzxz.net
459050105430
Page 6
②Total weight = weight of straight part 1 meter × effective length + weight of convex part of socket (calculated result, rounded off, retaining three significant figures)
2.1.2If a straight pipe with a flexible rubber ring interface or other interface form is required, it can be produced by negotiation between the supply and demand parties. According to the requirements of the demander, the small step at the "8" position in the socket can be cast. 2.1.3The fixed length of the cast iron straight pipe shall comply with the provisions of the effective length in Table 2. The weight of the short-length pipe supplied shall not exceed 10% of the order quantity (excluding the pipe for cutting the sample), and the allowable shortened length shall comply with the provisions of Table 3. For the same batch of orders and the same diameter pipes, only one fixed length can be supplied. Table 3 mm
Fixed length
5000, 6000
2.2 Appearance
2.2.1 The curvature of the cast iron pipe shall not exceed the provisions of Table 4. Table 4 mm
Nominal diameter Dg
≤150
200～450
≥500
L in the table represents the effective length of the pipe in meters. 2.2.2 The end face of the front iron pipe shall be perpendicular to the axis. 2.3 Dimensional deviation
2.3.1 Deviation of the outer diameter of the spigot and the inner diameter of the socket
The deviation of the outer diameter of the spigot and the inner diameter of the socket shall comply with the provisions of Table 5. Table 5mm
Nominal diameter Dg
≤450
500~800
Allowed shortening length
Outer diameter of plug
Bending
Inner diameter of socket
Page 7
≥900
2.3.2 Socket depth deviation
For nominal diameter less than 600mm, it is ±5mm, and for others, it is ±10mm. 2.3.3 Wall thickness deviation
The negative deviation of the wall thickness of the pipe body is (1+0.05T)mm; the negative deviation of the wall thickness of the socket is (1+0.05T)mm. 2.3.4 Length deviation
The length deviation of cast iron pipe is ±20mm.
2.4 Weight and its deviation
Cast iron pipes are delivered according to theoretical weight. The cast iron pipe from which the sample is cut shall be inspected according to the complete length. The negative deviation of the weight of each cast iron pipe is 5%.
2.5 Marking example
The continuous casting grey cast iron straight pipe with a nominal diameter of 500mm, a wall thickness of grade A and an effective length of 5000mm is marked as:
Continuous casting pipe A-500-5000GB3422-—82
Page 8
3.1 Chemical composition
3 Technical requirements
The phosphorus content of the continuous cast iron pipe shall not be greater than 0.30%, and the sulfur content shall not be greater than 0.10%. 3.2 Mechanical properties
3.2.1 The bending strength of the pipe ring shall comply with the provisions of Table 6 Table 6
Nominal diameter Dg, mm
≥300
350~700
≥800
3.2.2 The surface hardness shall not be greater than HB210. 3.3 Process performance
3.3.1 Water pressure test
The water pressure test shall comply with the provisions of Table 7.
Nominal diameter Dgmm
≤450
≥500
3.3.2 Air tightness test
Bending strength of pipe ring, kgf/mm2, not less than 34
Test pressure, kgf/mmz
When cast iron pipe is used for gas pipeline, if air tightness test is required, the test method shall be agreed upon by both parties. 3.4 Organization
Cast iron pipe shall be gray cast iron with dense organization and easy to cut and drill. 3.5 Surface quality
The inner and outer surfaces of cast iron pipe are not allowed to have significant defects such as cold shut, crack, dislocation, etc. that hinder the use. The depth of various local defects that reduce the wall thickness shall not exceed (2+0.05T) mm. Page 9
Local defects can be repaired with the consent of both parties. However, the repaired cast iron pipe must be re-tested with water pressure according to this standard.
3.6 Coating
3.6.1 The inner and outer surfaces of the pipe body can be coated with asphalt or other anti-corrosion materials. If cement mortar lining or no coating is required on the inner surface, it shall be agreed upon by the supplier and the buyer.
3.6.2 The coating shall be insoluble in water and shall not cause odor or taste in water. The content of harmful impurities shall comply with the relevant provisions of the Ministry of Health for water use.
3.6.3 Before coating, the inner and outer surfaces shall be smooth and free of rust and iron flakes.
3.6.4 After coating, the inner and outer surfaces shall be smooth, the coating shall be uniform and firmly adhered, and shall not be abnormal due to hot or cold weather.
Page 10
4 Test Methods
4.1 The dimensions of cast iron pipes shall be measured with calipers or samples and measuring tools with sufficient accuracy. 4.2 The surface quality and coating quality of cast iron pipes shall be inspected with the naked eye. 4.3 Chemical analysis shall be conducted in accordance with the provisions of GB223 (1~8)-81 and GB223.9~223.24-82 "Methods for Chemical Analysis of Iron and Steel and Alloys".
4.4 The pipe ring bending strength test shall be sampled at the spigot end of the cast iron pipe with qualified surface quality. s
Specimen size: For cast iron pipes with a nominal diameter less than or equal to 350mm, the pipe ring width is half of the average diameter; for cast iron pipes with a nominal diameter equal to or greater than 400mm, the pipe ring width is 200mm. a
During the test, place the sample on a hard pad and use a testing machine to test, as shown in Figure 2 (omitted). 0
4.5 Hardness test shall be conducted in accordance with the provisions of GB231-63 "Brinell Hardness Test Method". 3
The sample that has completed the strength test shall be processed into an appropriate sample for hardness test. 4.6 The water pressure test must be carried out before coating. When the specified pressure is reached, the pressure stabilization time shall not be less than 30s. A 0.75kg steel hammer shall be used to tap the pipe body. There shall be no leakage.
Page 11
5.1 Inspection and acceptance
5 Inspection rules
The inspection and acceptance of cast iron pipes shall be carried out by the supplier's technical supervision department. 5.2 Batch rules
Cast iron pipes shall be inspected and accepted in batches. Each batch shall consist of cast iron pipes with the same nominal diameter, the same wall thickness, the same fixed length and the same chemical analysis results. 5.3 Sampling quantity
5.3.1 The size, surface quality and coating quality of cast iron pipes shall be inspected one by one. 5.3.2 Chemical analysis Two samples shall be taken per shift (within 8 hours). However, when changing the charge, sampling must be carried out for chemical analysis. 5.3.3 Mechanical tests should be conducted on various cast iron pipes cast from the same furnace. When the production is less than or equal to 50 pipes per shift (8 hours), take one sample. When the production is more than 50 pipes, take two samples (4 hours apart, once for large pipes and once for small pipes). 5.3.4 Cast iron pipes must be subjected to water pressure tests one by one. 5.3.5 The weight of cast iron pipes should be randomly checked.
5.4 Re-test and judgment rules
If any one of the test results of the bending strength and hardness of the pipe ring does not meet the requirements of this standard, the pipe shall be scrapped and double samples can be taken from the same batch of cast iron pipes for re-testing of the unqualified items. If the re-test results are still unqualified, the batch of cast iron pipes shall be scrapped. At this time, the manufacturer can also submit each pipe for acceptance. If the chemical composition is unqualified, samples can be taken from the pipe body of the batch of cast iron pipes represented by the samples for re-testing. If the re-test results are still unqualified, the batch of cast iron pipes shall be scrapped. Page 12
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