:691.714
Fixed steel vertical ladders GB 4053.1-83
Fixed steel vertical ladders
______________________________________________________________________
Gs 17888.4-1999
Preliminary
"1
This standard is equivalent to ISO/DIS 1 412.4 in terms of technical content. It was developed using ISO/DIS 1 4122-4:1996. The main differences from ISO/DIS 1 4122-4
are the following:
1. The introduction to ISO/DIS 14122-4 has been eliminated, as it is only for the European Union.
2. The European standards or draft standards cited in ISO/DIS 14122-4 have been changed to national standards where national standards exist or are being developed, and only EN 353-1, which is actually used in the text, has been retained where national standards do not exist or are not yet under development. The rest of the text is not mentioned are not listed.
This standard is part 4 of the series of standards "Fixtures for the entry of machinery and industrial equipment". The series of standards *** consists of four standards,
the remaining three standards are:
Part 1: Selection of Fixed Installations for Entry Between Two Levels.
Part 2: Working platforms and access.
Part 3: Stairs, steps and guardrails.
Appendix A to this Standard is a reminder appendix.
This standard is proposed by the State Bureau of Machinery Industry.
This standard is put forward by the National Machinery Safety Standardization Technical Committee.
This standard is drafted by: Institute of Mechanical Science. Participants: Jilin Institute of Labor Protection Science, China Institute of Standardization and
Information Classification and Coding.
The main drafters of this standard: Ma Xianzhi, Shi Junwei, Xiao Jianmin, Zhang Mingxu, Li Qin, Gai Yongcai, Xiao Wei.
GB 17888.4-1999
ISO Preface
This standard is developed by CEN/TC 114 Working Group 17. It is part 4 of the standard
Fixed installations for the safe entry of machinery into machines and industrial equipment
. The several parts of the standard are:
Part 1: Selection of Fixed Installations for Entry Between Two Levels of Plane.
Part 2: Working platforms and access.
Part 3: Stairs, steps and guardrails.
Part 4: Fixed straight ladders.
The use of non-metallic materials (wood, composites, etc.) does not alter the application of this standard. In any case, all provisions of this standard
shall be observed.
Chinese people's **** and national standards
Mechanical safety
Fixed means of access to machines and industrial equipment
Part 4: Fixed straight ladders
GB 17888.4 a 1999
Sa fet y o f m ac hi ne ry -
Permanent means of access to machines and industrial plants-
Pa rt 4 :f ix ed l ad de rs
1 Scope
This standard specifies the safety requirements and preventive measures applicable to single- or double-column fixed ladders with or without fall arrest devices. preventive measures. This standard applies to fixed ladders used as access to machines. The ladder may be:
- an integral part of the machine;
- fixed to the machine;
- fixed to other elements in the vicinity of the machine.
For the selection of ladders for access to machines, see GB 17888.1,
2 References to standards
The following standards contain provisions which, by reference in this standard, constitute the provisions of this standard. At the time of publication of this standard, the versions shown are
valid. All standards are subject to revision, the parties using this standard should explore the possibility of using the latest version of the following standards.
GB 1 22 65.1-1997 Safety distance for machinery safety to prevent upper limbs from touching the danger zone
GB 1 22 65.3-1997 Minimum spacing for machinery safety to avoid extrusion of various parts of the human body
GB /T 1 5706.1-1995 Basic concepts of machinery safety and design general principles Part 1: basic terminology, methodology
GB /T 1 5706.2-1995 Basic Concepts of Machinery Safety and Design General Principles Part 2: Technical Principles and Specifications
GB /T 1 6755-1997 Mechanical Safety Safety Standard Drafting and Presentation Rules
GB / T 16856-1997 Principles of Mechanical Safety Risk Evaluation
GB 1 78 88.1- 1999 Fixed installations for safe access to machinery and industrial equipment Part 1: Selection of fixed installations for access between two levels
GB 1 78 88.2-1999 Fixed installations for safe access to machinery and industrial equipment Part 2: Working platforms and passages
GB 1 78 88.3-1999 Fixed installations for safe access to machinery and industrial equipment Part 2: Working platforms and passages
GB 1 78 88.3-1999 Fixed installations for safe access to machinery and industrial equipment Part 3: Working platforms and passages
GB 1 78 88.4-1999 Fixed installations for safe access to machinery and industrial equipment and industrial equipment Part 3: Stairs, steps and guardrails
GB / T 17889.2-1999 Ladders Part 2: Requirements, testing and marking
3 Definitions
In addition to the relevant definitions used in GB/T 15706.1, the following definitions are also used in this standard. Examples of the main definitions used in this standard
Subjects are shown in Figure 1,2,3,4.
3.1 Fixed ladders fixed ladders
National Quality, Technical Supervision Bureau 1999-10-18 approved 2000-10-01 implementation
Gs 17888.4-1999
Fixed ladders are a stable access to the elevated working position. It has firmly fixed
treading sticks on double or single uprights and an angle of inclination of 750^-90.
3.2 Fixed ladders with two uprights
Fixed ladders with each rung fixed between two uprights. The load is carried by two uprights (see Figure 2),
3.3 Fixed ladders with one upright
Fixed ladders with each riser fixed on both sides of the upright, with only one upright carrying the load (see Figure 3).
3.4 Ladder flight
3.4 Ladder flight
The continuous flight of a fixed ladder. >A continuous section of a fixed ladder that is:
a) for a platformless ladder, located between the starting surface and the arriving surface, or
b) between the starting surface and the nearest platform and the arriving surface and the nearest platform, respectively; or
.) Located between the rest platforms (see Figure 1)0
3.5 Rising height H of a fixed ladders
The vertical distance between the walking surface of the arrival surface at the top of the entire ladder and the walking surface of the starting surface at the bottom of the ladder (see Figure 1),
3.6 Height of ladder section h heighth o fth el adderf light
The vertical distance between the starting plane and the end plane of the ladder section.
3.7 FALL PREVENTION DEVICES anti-fallde vices
Technical installations for the prevention or reduction of the risk of a fall of a person from a fixed escalator.
The commonly used fall protection devices are:
- safety cages;
- fall arresters on rigid anchor rails.
3.8 Safety cages
A combined frame used to limit the risk of a person falling from a ladder (see Fig. 2),
3.9 Guided type fall arresters on rigid anchorage line (fall arrester)
Protective equipment fixed to a ladder and used in conjunction with the personal protective equipment that must be carried by each person before using the ladder. When the user
is associated with protective equipment fixed to the ladder, the equipment prevents a fall in the event of a loss of balance (see Figure 4),
3.10 Arrival level
The plane above the ladder or intermediate platform to which a person can walk after ascending.
3.11 departure level
The level below a ladder or intermediate platform from which a person starts to climb a fixed ladder.
3.12 intermediate platform
The platform through which the user of a ladder can reach the platforms of adjacent rungs of intersecting rungs (see Figure 1).0
3.13 rest platform
An area equipped with the necessary protective facilities designed to enable the user of a ladder to ascend or descend a fixed rung. users to rest before climbing up or descending to the ground
3.13 Rest Platforms
An area equipped with the required protective features. These resting platforms are equipped with doors and should be sized to allow for emergency intervention (see Figure 1)e
3.14 access platform
A platform arranged for walking on the arrival or departure side.
3.15 trapdoor
A normally closed device that opens to allow access to a platform or other similar horizontal structure.
3.16 lockout (intruder-proof protection)
A device to prevent access to a fixed escalator.
GB 17888.4-1999
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①Fixed bracket
②Steps
③Ladder frame
④Safety cage vertical
straight member
⑤Cage hoop
⑥Outlet part of the next
Hoop
⑦Plywood
⑥Skirting board
⑦Skirting board
⑥Skirting board
⑥Skirting board
6 ⑧ Skirting board
⑨ Inclined handrail
⑩ Platform tread
@ Door
⑩ Upper hoop
A I Exit section
B I Safety cage
Figure 2 Fixed straight ladder with safety cage
｝/ Deng
① Elevation of uprights
). Equal height of both stepping sticks
② Stepping stick ③ Anti-skid down protection device ④ Fixing point
b) Staggered stepping sticks on both sides
Figure 3 Single-post ladder
GB 17888. 4-1999
① Rigid anchor rails
② Fall prevention device
③ Connector
④ Standing post
5 Stepping Stick
Figure 4 Rigid Anchor Rail Type Fall Arrest Device
4 Safety Requirements and/or Facilities
4.1 General Requirements
The selection of materials for each element, and the determination of dimensions and mode of construction, shall be in accordance with the safety requirements of this standard and the various test data
data specified in Chapter 5.
Facilities for manned machines shall be calibrated under the same installation conditions as those used as reference machines, taking into account, if required, the corrosive phenomena of the environment
phenomena of vibration damage to the structure, deterioration of materials, etc.
All parts that may come into contact with the user should be designed so as not to cause harm (e.g., avoid sharp corners, weld burrs or rough edges
, etc.). Opening or closing the movable parts (doors, latches) should not create further danger (e.g. shearing
or accidental falls) to the person using the ladder or to people in the vicinity of the ladder.
All joints, hinges, supports, braces and mountings shall be such that the assembly is sufficiently strong and stable to ensure the safety of the
user under normal conditions of use.
4.2 Strength of Fixed Straight Ladders
4.2.1 General Requirements
The structure of ladders, platforms and safety cages (when installed) shall be able to withstand the expected loads as specified below:
4.2.1.1 Ladder Elements
Ladder elements shall meet the requirements of GB 17889.2. The maximum offset should not exceed 30m m (see 5.3.1 ).
In the case of a single-post ladder, the torsion test shall be conducted with a test force of 400N instead of the lateral bending test, and the deflection of the ladder shall not exceed
20 mm (see Figure 16). For the step stick, the load is applied over a length of 100 mm close to the lateral anti-slip device. The residual deflection of the tread stick should not exceed
3rd order of the length of the tread stick (see 5.3-2).
4.2.1.2 Safety cages
A safety cage is considered to meet the requirements if it has a permanent deformation of not more than 50 m m under a 10 00 N vertical load and not more than
10 mm under a 300 N horizontal load (see 5-2).
4.2.1.3 Fixed straight ladders fitted with a fall arrester
In the event that a user of a ladder falls downwards and is stopped by a fall arrester, a fixed straight ladder fitted with a fall arrester on a rigid anchor rail shall be capable of
supporting that load (see Chapter 5).
GB 17888.4-1999
4.2.2 Connecting elements
Connecting elements such as joints of all kinds, standoffs, hinges, supports and mountings shall be assembled sufficiently securely and stably to ensure the safety of the user under normal conditions of use
(see Chapter 5).
Fixed escalators fitted with fall arresters shall have connecting elements capable of withstanding the stresses resulting from the downward fall of a person intercepted by the fall arresters.
4.2.3 Platforms
See G B 17888.2.
4.3 Conditions for installation of fall arrest devices
Ladders shall be fitted with a fall arrest device if:
a) the height of the ladder section is 30 00m m or more;
b) the height of the ladder is equal to or less than 30 00m m but there is a risk of a fall at the landing. at which there is a risk of falling.
Note: A fall risk is considered to exist when the distance from the center of the ladder to the unprotected side of the platform (or similar structure) is less than 30,000 m m (see Figure 7).
4.4 Ladders
The main dimensions of the ladder should be as shown in Figures 5 and 6.
Gs 17888.4 I 1999
Worry
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150
0000T" Kawasaki V
Can be vice-buckled OO0n Ya HWOONN
Flying Jen-shaped card
65 0
; -:z00
①Tilt connecting element
②Door frame
Figure 5 Main dimensions of ladder and safety cage
350 Cluster A<400
700<B Rui 800
GB 17888.4 a 1999
Self-tick Chin
> 200
① See 4.4.1.2
② See 4.4.1. 2 and Fig. Sa
③ Requirements for access platforms and other surfaces are shown in 4.7 and Fig. 11
Fig. 6 Main dimensions of a single-column fixed ladder
Yin
The starting surface at the bottom of the ladder
Factory,... LIXI namely
GB 17888.4 a 1999
4.4.1 Position of stepping stick
4.4-1.1 Spacing of two stepping sticks
The spacing of two adjacent stepping sticks shall be consistent and shall be between 250^300m m. The stepping stick shall be placed in the same position.
4.4-1.2 Distance Between Sticks and Starting and Arrival Surfaces
The distance between the walking surface of the starting surface and the Level 1 sticks is recommended to be equal to the distance between neighboring sticks. In the case of movable machines used on uneven ground
, the distance between the walking surface of the starting surface and the 1st step may be a maximum of 400 mm,
and the top step shall be positioned at the same level as the walking surface of the arriving surface. b2 Installation for special use only
b) Polygonal stick structure
① No sharp edges to hurt hands
c) U-shape stick structure
Figure 8 Position and structure of stick
GB 17BBB.4-1999
4.4.1.3 Position of stick of single-column fixed ladder
The position of stick of single-column fixed ladder
The position of stick of fixed ladder
is the same as that of the other side of the column, with the two sides of the column. p>The treads on both sides of the column should be staggered at the same level or at equal distances (see Figure 6)0
4.4.1.4 Position of polygonal treads
The treads on polygonal treads should be at least 20m m. The treads on polygonal treads should be machined to a flat surface only when used for special purposes (see
Figure 8b).
4.4.2 Tread stick lengths
4.4-2-1 Tread stick lengths for double-column fixed straight ladders
Tread stick lengths should be in the range of 400^600m m (see Figure 5). However, where the proximity of the environment prevents them from being used for 400m m, it is permissible to use
shorter lengths between 300^400 mm. In this case, a check should be made beforehand to see if a favorable
position of the ladder can be found to allow the length of the tread stick to be 400 mm or longer.
4.4.2.2 Length of the stepping stick of a double-column fixed ladder and rigid anchor rail for fall arrester
The length of the stepping stick between the rigid anchor rail for fall arrester and the column should be at least 150 m m (see Fig. 9),
1) Rigid anchor rail
2) Column
3) Stepping stick
Ren}15o｝
Fig. 9 Double-column fixed straight ladder Step bar length and rigid anchor rail of fall arrester for double column fixed ladder
4.4-2.3 Step bar for single column fixed ladder
The length of the step bar between the column and the fall arrester should be between 150-250m m and the thickness of the column should be less than 80m m (see
Figure 6).
4.4.3 Cross-section of the stick
The diameter of the stick should be between 25^-35 m m and the width of the tread surface of the polygonal stick should be at least 20 m m. The cross-section of the stick should be easy to grasp by hand.
4.4.4.4 The cross-section of the stick should be between 150 and 250 m m and the thickness of the post should be less than 80 m m (see
Figure 6).
4.4.4 Stick surface
The surface of the stick should be free from damage, especially to the hands (see Figure 8c).
The surface of the Stick should prevent slippage of the foot (sole). When the risk of slippage increases due to environmental factors (e.g. oil, etc.), specialized anti-slip
measures need to be provided.
4.4.5 Anti-slip devices
Single-post fixed escalator rungs should be fitted with guards at the end of the rungs to prevent them from sliding out laterally. These anti-slip guards shall be at least 20 mm high (see A in Figure 6),
4.4.6 Distance between ladder and surrounding fixed parts
The distance between the ladder and the surrounding fixed parts shall be at least 650 m m at the front of the ladder, and at least
200 mm at the rear side of the rungs, and in the case of intermittent obstructions, the distance between the rear side of the rungs shall be at least 650 m m. The distance between the ladder and the surrounding fixed parts shall be at least 650 m m at the front and at least
200 mm at the rear side of the rungs. In the case of intermittent obstructions, the distance between the rear faces of the rungs shall be at least 150 mm (see Figs. 5 and 6),
4.5 Safety Cage
The safety cage shall start at a point between 22 00^ and 30 00 m m above the starting surface. On the entry side below the safety cage, the safety cage shall be free of
elements that obstruct the entry ladder. At the arrival plane, the safety cage shall extend to the height of the arrival plane guardrail (see figure 5),
The diameter of the safety cage within the cage hoop shall be between 700^-800m m (see D in figure 5). The distance from the pedal stick to the safety cage shall be
between 700^-800 mm.
GB 17888.4-1999
The clearance inside the cage measured on the transverse axis of the stepping stick, i.e., between the inner side of the cage and the stepping stick, shall be at least 700m m,
The distance between the two hoops shall not be more than 15,00m m, and the distance between the two poles of the cage shall not be more than 300m m. The hoops shall be placed perpendicularly to the poles of the cage
. The bars of the safety cage shall be fixed at equal distances inside the hoops. Their connecting elements shall be free from any rough surfaces that could catch or damage the
user.
The cage is not necessary if the surrounding structures (walls, machine components, etc.) at the front and sides of the ladder provide an equivalent level of fall protection.
4.6 Starting surfaces, reaching surfaces and platforms
Starting surfaces and reaching surfaces, as well as intermediary platforms and lateral platforms shall comply with the relevant requirements of GB 17888.2.
The guardrail as a guard against the risk of falling from height on the starting surface and the arrival surface, as well as on the intermediary platform and the transverse platform shall comply with the relevant requirements of GB 17888.3.
The guardrail shall comply with the relevant requirements of GB 17888.3.
The guardrail shall comply with the relevant requirements of GB 17888.3.
4.6.1 Starting surfaces
If the walking surface of a starting surface is more than 0.5 m high in relation to the surrounding area or the perimeter of a starting surface that is not capable of carrying a load (e.g., made of glass or synthetic material), the starting surface shall have a guardrail or guards to prevent a person from falling from a height.
4.61.1 Access platform
If the starting surface is on a structure such as a machine building and cannot be considered a plane that meets the requirements of GB 17888.2, an access
platform shall be provided.
4.6-1.2 Fixed straight ladders with safety cages
If the horizontal distance from the guardrail of a fixed straight ladder with a safety cage to the raised starting surface is not greater than 1.5 m, the guardrail shall be fitted with an extension
bar or the cage structure shall be extended down to the guardrail (see Figure 10),
The head of the extension bar shall meet at least the following requirements:
a) the shortest distance between the cage and the extension bar shall not exceed 400m m, or
b) the angle of the vertical line from the straight line connecting the upper portion of the extension bar to the closest portion of the safety cage shall be equal to or greater than 450;
c) the width of the extension at the height of the guardrail handrail shall be a minimum of 10,000m m, with the width of the upper end of the extension at least equal to that of the safety cage
. p>
The diameter of the cage. The headroom of the extensions shall be designed so that their area is not greater than 0.40 m2 and the horizontal width of these spaces shall not exceed
300 mm.
④ For guardrails without extensions,
@ the height of the extensions as determined by an angle of greater than or equal to 450,
6 the height of the extensions as determined by a distance of less than or equal to 400 mm;
④ the diameter of the safety cage. Diameter of the safety cage.
Figure 10 Extension bar perfect starting surface guardrail protection function
GB 17888.4 a 1999
4.6.2 Arrival surface
4.6.2.1 Access platform
If the arrival surface is on the structure of the machine, building and so on, and can not be considered as a work platform in line with the relevant requirements for the GB 17888.2 Requirements
When the access platform shall be provided.
4.6.2.2 Protection against falls from height
A suitable protection against falls from height, such as guardrails, shall be provided on the drop side of the access surface. The length of the guardrail on either side of the ladder drop axis should be at least
1 500 mm or more than the full length of the side of the reach when the side of the reach is less than 3 000 mm. This is independent of some kind of fall protection
device installed beyond this length.
4.6.3 Exit Points
4.6.3.1 Front or Side Exit
Ladders may exit from the front or side to the arrival surface.
The width of the exit shall be at least 600m m,
4.6 .3 .2 r7
To prevent a fall from the exit on the arrival surface, the exit shall be fitted with a door.
The door shall meet the following requirements:
a) the door shall not open in a direction towards the fall edge;
b) the door shall be designed so that it can be opened easily;
) (b) the door should close automatically, e.g. by means of a spring or by the effect of gravity.
d) The door shall, at a minimum, meet the requirements of GB 17888.3 for handrails and crossbars.
4.6.3.3 Platform exits, trapdoors
When required for technical reasons, the platform may have an opening to allow access to (or exit from) a ladder underneath the platform. The size of this platform
shall be at least equal to the diameter of the safety cage.
To prevent the risk of a fall through this opening, the opening shall be fitted with a flap door or provided with a guardrail with a door. The guardrail shall conform to the requirements of
GB 17888.3 and the door shall conform to the requirements of 4. 7. 3.2 of this standard.
Live panel doors shall be designed so that:
a) The opening shall be at least equal to the size required for ladder guard cages (D=700m m, see 4.5)0
b) The live panel door shall not be able to be opened downward, and shall move upward or horizontally.
c) The door should be easy to open and the opening operation should not present any new hazards. In order to ensure that the door closes automatically. It should not be able to hold itself
in the open position.
d) The closing of the door shall be automatic (e.g. by spring or gravity) and the closing operation shall not prevent the user from passing through the opening.
e) The door should not create any crushing or shearing points that could be reached by the user.
4.6.4 Measures for safe ascent and descent of fixed straight ladders
4.6.4.1 Measures for safe ascent and descent of two-post ladders (<3 000 mm) without fall arrest devices
A diagonal handrail shall be fitted between the tops of the two uprights and the handrail of the guardrail on the arrival surface. (see Figure 11).
4.6.4.2 Measures for safe ascent and descent of single-post ladders (<3 000 mm) without fall protection
A diagonal handrail should be fitted between the handrail on each side of the ladder and the handrail of the reach rail, starting at the penultimate rung (see
Figure 11).
4.6-4.3 Measures for Safe Ascent and Descent of Fall Arrested Ladders
These measures should enable the user of the ladder to reach the reach without disengaging the mobile fall arrest device.
4.6.5 Platforms
4.6.5.1 Installation conditions for platforms
GB 17888.4-1999
If the height of rise of a fixed ladder, H, is greater than lom, the ladder shall be provided with a platform.
The ladder section between the arrival surface, the starting surface and the closest platform respectively or between two adjacent resting platforms (see Fig. 3b), Fig. 3c))
The height h shall be not more than 6 m,
①Walking surface on the arrival surface
②Door
③Guardrail
④Inclined handrail
⑤No fall arrester for a single
4.6.5.3 Rest platforms
Rest platforms shall have a minimum width of 700m m and the portion of the rest platform located in the gap near the ladder shall be fitted with doors and handrails. Their
dimensions are to be designed to meet the requirements for carrying out emergency interventions.
4.6-5.4 Staggered ladder sections
If required, two successive ladder sections may be adjacent without separated platforms by arrangement of the machine or surroundings (see
Figure 5). In this case, the following ladder section should extend at least 2 200 mm above the resting platform to provide a good
handrail for the user of the ladder (see Fig. 12),
GB 17888.4-1999
Fig. 12 Example of intermediate platforms (interlocking ladder sections)
4.7 General Requirements for Locking
In order to avoid access by unqualified persons, the following provisions may be used when it is necessary to install a lockout on a fixed ladder. In the ladder to reach through the
Possible hazards in the place see Appendix A of GB/T 16755-1997,
Lockout should be designed so as not to change the characteristics of the ladder after the installation of the lockout. When the latch is closed, should not significantly increase the ladder itself needs space
Space. When the latch is open, it shall not interfere with the use of the rungs and shall not reduce the space bounded by the safety cage and the other sides of the ladder.
Appendix A indicates the different heights at which access restrictions may be applied, and in all cases the direction of egress shall be kept clear.
The design of the closure needs to avoid risks such as head-banging, finger-pinching, etc. during use. For this reason, it is not recommended to use systems that rotate on a horizontal axis.
Locks should be designed so that:
- Opening from the starting surface can be done by the operator standing on the ground;
- Opening can be done with a single movement.
When the hazardous area includes several entrances and exits, all locks should be equipped with an emergency opening device.
Figures 13 and 14 show the area covered by the protection given by the latching elements:
- Class A elements are intended to prohibit direct approach to the ladder;
- Class B elements prohibit access to the ladder;
- Class C elements prohibit the use of the ladder through the protected area surrounded by the two elements mentioned above.
The increase in the degree of effectiveness of the locking is achieved by the joint use of elements A,A+B and A+B10C.
GB 17888.4 I 1999
a) Area protected by a type A locking element
0 restricted population
Figure 1 3
b) Area protected by a type B locking element.) Area guarded by type c latching element
Heart free exit
Area guarded by lower latching element of ladder
a) Area guarded by type A latching element
!!!! Restricted manhole
Figure 1 4
b) Area guarded by type B latching element c) Area guarded by type C latching element
Free exit
Area guarded by ladder upper latching element
GB 17888.4 a 1999
5 Inspection
Safety requirements and/or facilities in Chapter 4 can be determined by measuring, inspecting, or checking the ladder's safety requirements
Safety requirements and/or facilities in Chapter 4 can be determined by measuring, inspecting, and checking the ladder's safety requirements and/or facilities. or facilities can be tested by measurement, inspection, calculation and/or test. When tests are used, they shall be carried out in accordance with the test procedures described in this chapter
.
5.1 Tests of double-post fixed ladders
The elements of ladders shall meet the following tests specified in GB/T 17889.2:
- Strength test of ladders
-Bending test of ladders
- Lateral bending test of ladders
- Bending test of rungs
- Torsion test of rungs
These tests are carried out on a ladder in accordance with the principles in 4.1 of GB/T 17889.2-1999 in the order indicated above.
For the strength, bending and transverse bending tests the distance L considered is the distance between two adjacent supports of the ladder.
Criteria for passing the bending test: under load, the maximum permissible deflection shall be less than 5X I ,2X 1 0-em m and not more than 30m m.
5.2 Safety cage test
This test is carried out with the ladder in use at the site conditions. The safety cage is fixed to the ladder.
A vertical load of 10,00 N is applied to the most unfavorable position of the safety cage with the help of a 100 m m wide clamp.
The permissible permanent deformation, measured at the point of application of the load, is not more than 50mm,
The horizontal load of 300N is then applied with the help of 100mm wide clamps to the point on the cage considered to be the most unfavorable. The permissible permanent deformation measured at the point of load application
does not exceed 10 mm.
5.3 Tests of single-column fixed ladders
5.3.1 Ladder elements shall meet the following tests specified in GB/T 17889.2:
- Strength test
- Bending test
- Treadle torsion test
For the strength and bending test the distance L considered shall be the distance between two adjacent supports of the ladder.
The passing criterion for the bending test shall be that the maximum permissible deflection under load shall be less than 5X L ZX 1 0-6m m and not more than 30m m,
5.3.2 Strength of the rungs
The bending test of the rungs of a single-post ladder shall be carried out in accordance with the diagram.
A preload of 20 N is applied perpendicularly to the tread of the rungs for a period of 1 m in. The position of the rungs after removal of the preload is taken into account
as a reference position for the load test.
The direction of the preload and the test load of 2600 N shall be perpendicular to the tread of the rungs. The preload and test loads are evenly distributed over a 100 mm length of the lateral anti-slip out device near the tread bar.
The residual deflection of the stick after removal of the test load shall not be greater than 3% of the length of the relevant stick o. The measurement point is 50 mm from the lateral anti-slip
out protection of the stick; the direction of measurement is the same as that of the line of action of the test load. The offset is measured within 1 min
after removal of the test load.
5.3.3 Strength of columns
The ladder shall be subjected to the stresses applied in accordance with Figure 16.
The direction of the 40 0N test force is perpendicular to the end face of the ladder. The distance of the supports is four times the distance between the treads (see Figure 16).0
The deflection of the ladder under the load shall not exceed 20m m. The point of measurement is 50 mm from the transverse anti-slip out guard on the treads which are subjected to the test force.
The ladder shall be subjected to the test force in the direction of the line of action of the test force. The direction of measurement is the same as the direction of the line of action of the measuring load.
Gs 17888.4-1999
①Acting line
Figure 15 Test method for single-post ladder treads
Test load
40 0 N
①Acting line
②Measuring point
③Quadruple spacing of the treads
Figure 16 Twisting test for single-post ladders Torsion test
5.4 Support test
5.4.1 Double-column fixed straight ladder
The strength of the support of a double-column fixed straight ladder shall be considered to be calculated by a force of 30,00N per column acting in the direction along the centerline of the columns (see
Figure 17).
Four bearings per upright may be considered to carry forces that will be transmitted to surrounding fixed parts (e.g. walls, enclosures).
GB 17888.4-1999
3000N
①Steps
②Posts
③Supports
④Fasteners
Figure 17 Fixed point strength and load of double-post fixed escalator
5.4.2 Single-post fixed escalator
Single-post fixed escalator
Single-post fixed escalator is supported by a single column. The support strength of a single-column fixed ladder should be considered to be calculated as a force of 60,000N acting in the direction of the centerline of the column (see Fig. 18),
with a maximum of four supports per column, it can be assumed that the force will be transferred to the surrounding fixed parts (e.g., walls, enclosures).
6000N
)
①Steps
②Posts
③Brackets
④Fasteners
Figure 18 Strength of fixing point and load of single-post fixed ladder
GB 17888.4-1999
Appendix A
(Referred to) Protection against entry from the top
Figure A2 Protection against entry from the center
Protected area divider
Divider divider
Divider divider
Divider protected area city
x , blocked
Figure A3 Protection against multiple entries
Reference:
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