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GB/T 31255-2014 English PDF (GBT31255-2014)

GB/T 31255-2014 English PDF (GBT31255-2014)

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GB/T 31255-2014: Safety of machinery -- Safety specification for the design of industrial type stairs, working platforms and walkways

This standard specifies the safety design specifications for industrial stairs, working platforms and walkways. This standard applies to industrial stairs, working platforms and walkways used to access the fixed facilities of machinery.
GB/T 31255-2014
GB
NATIONAL STANDARD
OF THE PEOPLE REPUBLIC OF CHINA
ICS 13.110
J 09
Safety of machinery - Safety specification for the design of
industrial type stairs, working platforms and walkways
ISSUED ON. DECEMBER 05, 2014
IMPLEMENTED ON. JULY 01, 2015
Issued by. General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China;
Standardization Administration of the People's Republic of
China.
Table of contents
Foreword ... 3
Introduction ... 4
1 Scope ... 5
2 Normative references ... 5
3 Terms and definitions ... 6
4 General ... 10
5 Material ... 10
6 Stairs ... 11
7 Working platforms and walkways ... 13
8 Edge protection ... 15
9 Protective structure ... 15
References ... 18
Foreword
This standard was drafted in accordance with the rules given in GB/T
1.1-2009.
This standard was proposed by the National Machinery Safety Standardization Technical Committee (SAC/TC 208).
The drafting organizations of this standard. Tianjin Jinmao Group Co., Ltd., China Productivity Center for Machinery, Changchun Institute of Mechanical Science and Technology Co., Ltd., Nanjing Forestry University Institute of Optical and Electrical Engineering.
The main drafters of this standard. Li Qin, Zhang Xiaofei, Wang Shengjiang, Li Jie, Ning Yan, Wang Xuezhi, Ju Ronghua, Cheng Hongbing, Li Chunping, Fu Huiqing, Liu Zhiyong.
Introduction
The mechanical safety standards are structured as follows.
- Category A standards (fundamental safety standards), providing the basic concepts, design principles and general characteristics applicable to all machinery;
- Category B standards (general safety standards), involving a safety
feature in machinery or a category of safety devices with wide application range.
?€? Category B1, safety features (such as safety distance, surface
temperature, noise) standard;
?€? Category B2, safety devices (such as two-hand control device, interlock device, pressure-sensitive devices, protective devices) standard.
- Category C standards (machinery safety standards) that specify a detailed safety requirement for a particular machine or group of machines.
In accordance with GB/T 15706, this standard belongs to category B standard. Category C standards may supplement OR modify the terms of this standard. For machines designed and constructed in accordance with the category C standards, if the terms in the category C standards are inconsistent with the category A or B standards, it is preferred to use the category C standards. Safety of machinery - Safety specification for the design of
industrial type stairs, working platforms and walkways
1 Scope
This standard specifies the safety design specifications for industrial stairs, working platforms and walkways.
This standard applies to industrial stairs, working platforms and walkways used to access the fixed facilities of machinery.
This standard also applies to industrial stairs, working platforms and walkways that are not fixed to the machine BUT may need to be removed or moved to aside of the machine (e.g., tools for replacing large presses) during certain operations on the machine.
Other industrial stairs, working platforms and walkways may also make
reference to AND use this standard.
2 Normative references
The following documents are essential to the application of this document. For the dated documents, only the versions with the dates indicated are applicable to this document; for the undated documents, only the latest version (including all the amendments) are applicable to this Standard.
GB/T 15706-2012 Safety of machinery - General principles for design - Risk assessment and risk reduction
GB 17888.1-2008 Safety of machinery - Permanent means of access to
machines and industrial plants - Part 1. Choice of a fixed means of access between two levels
GB 17888.2-2008 Safety of machinery - Permanent means of access to
machines and industrial plants - Part 2. Working platforms
GB 17888.3-2008 Safety of machinery - Permanent means of access to
machines and industrial plants - Part 3. Stairs, stepstairs and guard-rails All step spacing in the stair section shall be consistent AND the tolerance shall comply with the requirements given in 6.6. The relationship between the stair step spacing h and the tread distance g shall not be changed with the pitch line, AND the tolerances of them shall be consistent.
6.6 Tolerance
The consistency of the step spacing h and the tread distance g is the most important for the safety of the user. The tolerance of the step spacing h and the tread distance g shall be ?? 5 mm within the same stair section of a stair. 6.7 Outdoor stairs
If the stairs are exposed to the outside AND are not only for access to the fixed facilities of the machinery, the rising height H shall not exceed 6 m. Otherwise, it shall be protected, such as enclosed with non-combustible materials (SEE 9.7).
6.8 Step
The step shall comply with the safety requirements as specified in Chapter 4 of GB 17888.3-2008; AND it shall take appropriate anti-slip measures OR at least have a non-slip leading edge with a width of not less than 25 mm.
For hollow step stairs, the overlapping part of the step shall not be less than 16 mm, AND the depth of the leading edge shall be between 25 mm ~ 50 mm, in order to improve visibility.
6.9 Stair beam
The stair beam shall have sufficient rigidity to minimize the lateral deflection; AND the distance beyond the leading edge of the bottom step shall not exceed 50 mm (SEE Figure 1).
6.10 Stair platform
The stair platform shall be designed to comply with the requirements of Chapters 7 and 8.
The length of the stair platform l (SEE Figure 3) shall not be less than the stair net width or 850 mm, whichever is greater.
6.11 Handrails
Straight staircase, stair section platform and helical and spiral stairs shall have continuous handrails complying with the relevant requirements of Chapter 9. 7.2.2 In the case of full consideration of the possibility that machinery or other objects may be placed on working platforms or walkways, the designer shall allow the square (center distance 1000 mm and side length 300 mm) within the region of the working platform or walkway to be able to withstand a
concentrated load of not less than 1.0 kN, AND increase additional allowance considering the dynamic load.
7.2.3 After applying the design load, the deflection of the working platform or walkway shall not exceed 10 mm or 0.5% span, whichever is smaller.
7.3 Fixation
Working platforms and walkways shall not be fixed by their own weight.
When the fixation element which depends on tensile force only is used only, its working load factor shall be not less than 1.5.
The designer shall consider whether the corrosion or fatigue stresses will have a significant effect on the fixation of the working platform or walkway. 7.4 Handrails
All open sides of the working platform and walkway shall be fitted with handrails that comply with the relevant requirements of Chapter 9.
7.5 Skirting board
All open sides of the working platform and walkway as well as the downside of the first step of the open stair shall be installed with the skirting boards complying with the requirements of Chapter 8.
7.6 Walkway
The walkway shall generally be horizontal. However, if it is unavoidable to use inclined walkway, it shall pay special attention to ensure that personnel use the walkway can get enough friction. The slope of the walkway shall not exceed 10??.
7.7 Leading edge
If the walkway does not have anti-slip measures, the tops of all stairs and the positions accessing to the stairs shall have anti-slip leading edges, which shall match with the leading edge of the stair steps (SEE 6.7).
The joints of the continuous guardrail shall be located at the minimum stress point AND shall not exceed 150 mm to the center line of the post. The position of the joint shall not be located outside the end post OR between the two continuous posts at the corners. The joint shall be free from any sharp edges or burrs.
9.4 Post
The posts shall not be installed on the skirting board unless otherwise they can be used as the structural elements of skirting board.
9.5 Clearance
To ensure that the hand can firmly grasp the handrails, it shall provide more than 75 mm clearance below the handrail.
9.6 Self-closing door
At a potentially dangerous area, such as the gap at the stair top handrail, it shall be protected through using the self-closing door. The closing of the self-closing door shall be slow, AND it shall be designed to open towards the stair section platform insi...

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