Steps are mainly used for descending and climbing up maintenance manholes and inspection wells of various buildings. This standard specifies the classification, technical requirements, inspection methods, inspection rules, marking, packaging, transportation and storage of iron steps. This standard applies to steps made of malleable iron or ductile iron used for descending and climbing steps in maintenance manholes, fire ladders and inspection wells such as sewers, underground gas pipelines, tap water pipelines, underground cable channels, telecommunications and electricity, building fire ladders, communication channels, etc. Steps made of other materials can refer to this standard. JG/T 120-2000 Steps JG/T120-2000 Standard download decompression password: www.bzxz.net

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People's Republic of China Construction Industry Standard JG/T120——2000
Steps
Manhole steps
2000-06-12 Issued
2000-10-01 Implementation
People's Republic of China Ministry of Construction Issued
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JG/T120—2000
This standard adopts the British standard BS1247—1990 "Manhole Steps". Steps are mainly used for descending and climbing in maintenance manholes and inspection wells of various buildings. This standard is compiled in accordance with the provisions of GB/T1.1—1993 and GB/T1.3—1997. Appendix A of this standard is the appendix of the standard.
This standard is proposed by the Standard and Quota Research Institute of the Ministry of Construction. This standard is managed by the China Academy of Building Research, the technical unit responsible for building engineering standards of the Ministry of Construction.
The drafting units of this standard are: Building Mechanization Research Branch of China Academy of Building Research, Guiyang Bada Steel Co., Ltd.
The main drafters of this standard are: Shen Yingying, Chen Wenlong, Yang Guojun, and Yi Rong. This standard is entrusted to the Building Mechanization Research Branch of China Academy of Building Research for interpretation.
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JG/T120—2000
BS Foreword
This standard BS1247 was formulated under the guidance of the Road Engineering Standards Policy Committee to replace the cancelled BS1247-1975. The old version of this standard made strict regulations on the size of the steps. In this edition, the concept of performance standards is adopted according to the new test requirements, and only key dimensions are specified. The material range includes steel, and double-foot steps (also called "ladder irons") are added. The total amount of information that should be marked on the sub-manhole is increased (this is Article 8).
Corner ring rod steps are rarely seen at present and have been deleted from the standard. It is expected that there will be updated content added soon after this edition, which will include materials such as sprayed steel, sprayed aluminum alloy and aluminum alloy for the manufacture of manhole ladders. Compliance with British Standards does not provide immunity from legal liability. I
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People's Republic of China Construction Industry Standard Steps
Manhole steps
JG/T120—2000
This standard specifies the classification, technical requirements, inspection methods, inspection rules, marking, packaging, transportation and storage of iron steps.
This standard applies to steps made of malleable cast iron or ductile iron used in maintenance manholes, fire ladders and inspection wells such as sewers, underground gas pipelines, water pipelines, underground cable channels, telecommunications and electricity, building fire ladders, communication channels, etc. Steps made of other materials can refer to this standard. Cited 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 are subject to revision, and parties using this standard should explore the possibility of using the latest version of the following standards. GB/T1348—1988 Ductile iron parts
GB/T2828—1987
GB/T9440—1988
Batch inspection counting sampling procedure and sampling table (applicable to inspection of continuous batches)
Mallet cast iron parts
a) Single-leg iron steps for masonry structures;
Approved by the Ministry of Construction of the People's Republic of China on 2000-06-12 Engineering Construction Standard Full Text Information System
Implementation on 2000-10-01
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b) Double-leg iron steps for masonry structures;
c) Single-leg iron steps for concrete structures;
d) Double-leg iron steps for concrete structures.
3.1 See Table 1 for step types
Table 1 Step types
Type code
For concrete structures
Single-leg iron step
For concrete structures
Double-leg iron step
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Schematic diagram
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Type code
For concrete structures
Single-leg special step
Concrete superstructure
Double-leg iron step
Table 1 (End)
The step model consists of name code, characteristic code, main parameter code and modification serial number
New national
Main parameters (tail size × front size × pedal length), m characteristic code: expressed by type code
Name code: T
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3.2.2 Example
a) The tail size is 115mm, the front size is ≥100mm, the pedal length is 150mm, and the masonry structure uses a single-foot step.
Marked as: TQD115×(>100)X150
b) After the first modification, the tail size is 50mm, the front size is 100mm, the pedal length is 400mm, and the concrete structure uses a double-foot step. Marked as: THSH50×(≥100)X400A Requirements
General requirements
According to the specified product drawings
4.1.2 The material of the step should be the forgeable cast iron parts with mechanical properties not lower than KTH350-10 specified in GB/T9440 or the ductile iron parts with mechanical properties not lower than QT450-10 specified in GB/T1348. 4.2 Distortion requirements
The distortion requirement for the single-foot step board surface should not exceed 3mm, and the distortion requirement for the double-foot step board surface should not exceed 5mm.
4.3 Resistance requirements
During the step load test, under the action of 2.5kN vertical force, there should be no cracks or other damage after 1min of load, and the deformation should not exceed 5mm. After unloading, the residual deformation should not exceed 1mm.
4.4 Anti-slip requirements
The surface of the step can adopt a convex or mesh anti-slip surface with a height of not less than 1.5mm (see Figure A1~Figure A4).
4.5 Appearance quality requirements
4.5.1 There shall be no defects such as pores, cracks, cold shuts, shrinkage holes, slag inclusions, and inability to pour on all parts of the step.
4.5.2 The edges and handholds of the step are not allowed to have sharp seams or other protrusions that affect the use.
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4.5.3 There shall be no more than three sand holes on the surface of the step with a depth of more than 2mm and an area of ​​less than 5mm2, and there shall be no sand holes larger than 5mm2. 4.5.4 The height (or depth) of other convex (or concave) surfaces shall not be greater than 1mm. The galvanized layer on the surface of the galvanized step shall be uniform.
There should be no black spots on the surface of the galvanized step.
There should be no exposed iron on the surface of the galvanized step.
There should be no coating peeling off on the surface of the galvanized step. Test method
Twisting test
As shown in Figure 1, the step is supported by two adjustable supports. The supports are adjusted so that the three points a, b, and c on the step board are equidistant from the horizontal plane, and the change in height along its length is measured.
5.2 Bending test
Schematic diagram of torsion test
Clamp the specimen firmly to make it in a cantilever state, and load it evenly on the center of the step tread at a loading speed of 40N per second (as shown in Figure 2). Load it to 2.5kN and keep it for 5
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1min, unload it to 0.5kN, read the deformation number in the center of the tread, and use the data as the measurement basis. Repeat the test and record the deformation when the load is increased to 2.5kN and kept for 1min. Unload it to 0.5kN and record the residual deformation. Figure 2 Schematic diagram of bending test
Test rules
Test classification
The inspection of steps is divided into inspection and type inspection. 6.1.1
Factory inspection
Before leaving the factory, the product must be inspected by the factory inspection department according to the anti-slip requirements in 4.4 and the appearance quality requirements in 4.5. The torsional performance and bending performance are tested according to the production 5.1 piece is sampled from 000 pieces for inspection, and it can leave the factory only after it passes the inspection.
6.1.2 Type inspection
Type inspection includes appearance inspection, anti-slip requirement inspection, distortion inspection and bending resistance inspection. The distortion requirement and bending resistance requirement shall be inspected according to 4.2 and 4.3 respectively. Type inspection shall be carried out in any of the following situations.
a) Trial determination and identification of new products or old products transferred to factory production; b) After formal production, if there are major changes in structure, materials, and processes, which may affect product performance;
c) Every six months during normal production;
d) When the product is resumed after long-term suspension; e) When the factory inspection results are significantly different from the last type test; f) When the national quality supervision agency proposes to conduct type testing. If the type test fails, the product will be stopped from acceptance and shipment, and the manufacturer will take effective measures until the type test passes before resuming acceptance. 6.2 Sampling method
6.2.1 Product inspection shall be carried out in accordance with the normal inspection secondary sampling plan specified in GB/T2828 (see Table 2)
Item category
Main items
Acceptance items
Inspection level
Twisting performance
Anti-check performance
Anti-slip requirements
(4.5.7)
Batch range
151~500
501~1200
91~150
151~500
501~1200
Random sampling shall be adopted for inspected products.
6.3 Determination method
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Sample size
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6.3.1 The main items of a single product must be qualified, and two items of general items are allowed to be unqualified, otherwise it is unqualified.
6.3.2 Batch products shall be determined according to Table 2. 7 Marking, packaging, transportation and storage
7.1 Marking
The product mark should be set on the product certificate and should indicate: a) manufacturer name;
b) trademark,
c) product model,
d) quantity.
7.2 Packaging
Products should be packaged in categories and tied firmly. The weight of each box should not exceed 30kg. Each box should have a product certificate, which should indicate: young logo,
) factory date;
) inspector's stamp.
7.3 Transportation
Various transportation methods can be adopted according to user requirements. Storage
Products should be stored in a rust-proof and moisture-proof manner and laid flat. 8
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Appendix A
(Standard Attachment)
Minfeng Garden Garden Garden Garden Garden Park
Figure A1 Single-leg iron step for masonry structure
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