Safety Requirements for Portable Metal Ladders 便携式金属梯安全要求

Transcription

1 ICS C 68 NATIONAL STANDARD OF THE PEOPLE S REPUBLIC OF CHINA 中华人民共和国国家标准 GB Replace GB and GB Safety Requirements for Portable Metal Ladders 便携式金属梯安全要求 How to BUY & immediately GET a full-copy of this standard? Search --> Add to Cart --> Checkout (3-steps); 3. No action is required - Full-copy of this standard will be automatically & immediately delivered to your address in 0~60 minutes. 4. Support: Sales@ChineseStandard.net. Wayne, Sales manager Issued on: June 26, 2007 Implemented on: February 1, 2008 Jointly issued by: The General Administration of Quality Supervision, Inspection and Quarantine (AQSIQ) and The Standardization Administration Committee (SAC) of the People s Republic of China

2 Foreword The provisions of all chapters, except chapters 1, 2 and 3, shall be compulsory in this Standard. This Standard is the combination of revision to GB "Safety Standard for Light-metal Extension Ladders" and GB "Safety Standard for Light Metals Portable Stepladder". This Standard replaces GB "Safety Standard for Light-metal Extension Ladders" and GB "Safety Standard for Light Metals Portable Stepladder". Compared with GB "Safety Standard for Light-metal Extension Ladders" and GB "Safety Standard for Light Metals Portable Stepladder", this Standard has the major technical differences as follows: -Extend the application scope of the Standard, cover the safety requirements for two-section extension ladder, stepladder, as well as three-section extension ladder, single ladder and combination ladder; -Add the normal load grading for ladders and the structure performance requirements corresponding to normal load; -Add metal fitting load test requirements, rung torsion test requirements, stile cantilever bending test requirements and stile cantilever drop test requirements for extension ladder and single ladder; -Add the following test requirements for stepladder: stile bending test requirement, step (or rung) and stile shear strength test requirements, torsional stability test requirements, transverse pull test requirements, front and back stile cantilever bending test requirements, front and back stile cantilever drop test requirements and stile torsion and spreader test requirements; -Cancel the horizontal bending test requirement for stepladder; -Make full revision to other contents on structural requirement, operating requirement and test requirement. This Standard is proposed by the State Administration of Work Safety. This Standard is under the jurisdiction of the National Technical Committee 288 on Safety Production of Standardization Administration of China (SAC/TC 288). Drafting organizations: Jilin Academy of Safety Science and Technology, ChangChun University of Technology and Suzhou Baofu Light Industry Product Co., Ltd. Chief drafting staffs: Xiao Jianmin, Zheng Fanying, Qu Sheng, Han Lianying and Lu Xiongying All previously replaced editions hereof are as: -GB ; -GB

3 Contents 1 Scope Normative References Terms and Definitions General Structural Requirements for Extension Ladder and Single Ladder Structural Requirements for Stepladder Structural Requirements for Combination Ladder Operating Requirements Test Requirements for Extension Ladder and Single Ladder Test Requirements for Stepladder Test Requirements for Combination Ladder Marking... 38

4 NATIONAL STANDARD OF THE PEOPLE'S REPUBLIC OF CHINA 中华人民共和国国家标准 GB Safety Requirements for Portable Metal Ladders 便携式金属梯安全要求 1 Scope This Standard specifies design/manufacturing safety requirements, test requirements, safe operation requirements and others for portable metal ladders. This Standard is applicable to portable metal extension ladder (two-section or three-section extension ladders), portable metal single ladder, portable metal stepladder and portable metal combination ladder used on production activities. 2 Normative References The provisions of following documents, through reference of this Standard, constitute provisions of this Standard. For those documents which are dated, neither their subsequent amendment (excluding correction) nor their revision applies to this Standard. However, the parties who enter into agreement according to these specifications are encouraged to research whether the latest edition of the document is applicable. For those documents which are undated, the latest edition of the normative document is applicable. GB/T Ladder - Part 1: Terms, Types and Function Dimensions 3 Terms and Definitions For the purposes of this Standard, the following terms and definitions and the ones given in GB/T apply. 3.1 Portable metal extension ladder Portable leaning ladder formed by two or three sections, whose length is adjustable and primary components (stile and step/rung) are made by metallic material 3.2 Portable metal single ladder (straight ladder) Portable leaning ladder formed by only a section, whose length is non-adjustable and 1

5 primary components (stile and step/rung) are made by metallic material 3.3 Portable metal stepladder Portable free-standing ladder formed by front and back parts through twisting joint, whose primary components (stile and step/rung) are metallic material made; its structure may be single-side (front side) ascendable (like single-side stepladder) or both-side ascendable (like double-side stepladder and trestle ladder). 3.4 Portable metal trestle ladder Portable free-standing ladder whose length is un-adjustable, primary components (stile and step/rung) are metallic material made and two same sections are connected with hinge on the top, forming equal angles to the bearing surface 3.5 Portable metal combination ladder Portable ladders used as stepladder, single ladder or extension ladder, whose primary components (stile and rung) are made by metallic material 3.6 Stile (rail) Side components of a ladder, which support step (or rung) or other bearings 3.7 Step (rung) Component of a ladder, which is stepped by user for ascending. Where its front-back depth is larger than 20mm and less than 80mm, it is called as rung; where the depth is equal to or larger than 80mm, it is called as step. 3.8 Ladder foot (ladder shoe) Component at a ladder bottom contacting the supporting surface 3.9 End cap Component at top of a ladder section or head end of extended section, which is used to covering sharp edge or burr of stile 3.10 Top cap Horizontal component on the top of a portable metal stepladder 3.11 Top step (rung) Top surface of the first step (or rung) below top cap in a portable metal stepladder. Where a ladder structure has no top cap, the top step (or rung) is the first step (or rung) below the stile top Spreader A component used to keep the operating angle and prevent the two parts sliding outside or folding inside when the stepladder is open

6 Angle of inclination / inclination angle The included angle from two stile planes to the horizontal plane 3.14 Working length The length measured (along the stile) from the ladder bottom supporting point to the top supporting point when the ladder is in the predetermined operation state 3.15 Maximum working length (maximum extension length) The working length of an extension ladder when its extensible sections are extended to the maximum place (keeping the required minimal lap) 3.16 Highest standing level The vertical distance from the supporting plane (ladder bottom) to the highest step (or rung) that the user is allowable to ascend to in the predetermined state 3.17 Inside clear width The distance measured (parallel to the step / rung) between flanges on two stile of a ladder 3.18 Normal load The maximum load (including weights of ascender, and carried materials and tools) that a ladder can bear in the predetermined operation condition 3.19 Test failure Visible failure to ladder structure or component(s) due to test(s), including corrugation, distortion, shearing, tearing or breakdown 3.20 Ultimate failure Severe failure to ladder structure or component(s) due to test, which causes that the ladder structure or component(s) due cannot work properly 3.21 Visible damage Failure that can be distinguished and identified clearly by visual check 4 General 4.1 Normal Load Portable metal ladders shall be able to bear a normal load not less than 90kg and identified by the normal load. By load bearing capacity, normal loads of ladders may be classified as four classes: 90kg, 100kg, 110kg and 135kg. 4.2 Corrosion Resistance Ladders shall be made of corrosion-resistant material as much as possible; otherwise, they shall be applied with anti-corrosion treatment. 3

7 4.3 Exposed Metal Surface Exposed metal surface of a ladder shall be free of sharp edge, burr and other structural defect. 4.4 Bolt Connection Hole punching or drilling shall be accurate for bolt holes, and burr larger than 0.8mm in height shall not be left after hole working. At least 1.5 circles of a thread shall be exposed out of the nut. All nuts shall be lock nuts or with lock washers, or locked with equivalent mode after affirmation. 4.5 Riveting Rivet holes shall be punched or drilled accurately and burr larger than 0.8mm in height shall not be left after hole working. All rivets shall be plump and smooth, free of visible crack or chink; the contact between riveting pieces shall not result in rotation; the gap between the rivet head and riveting piece surface or between the two components connected by the rivet shall not be larger than 0.13mm. 4.6 Welding All welding shall be free of undercut, crack and visible surface pore. 4.7 Spacing between Steps (or Rungs) The center-to-center spacing of adjacent steps (or rungs) shall not be larger than 350mm As for metal stepladder, its top step (or rung) may be 450mm below the top cap, where the measures to limit stepping into the opening unconsciously or the stepping surface of top step (or rung) extends inwards and intersects with the line perpendicular to the lower front limb of the top cap. 4.8 Step (or Rung) Connection Rigid connection shall be adopted for step (or rung) and stile, and its strength shall satisfy the test requirements specified in 9.7and The connecting mode for hemicycle / plain rung with stile shall enable its top surface to keep horizontal when the ladder is set as the normal working position. 4.9 Step (or Rung) Surface The top surface of steps (or rung) shall be machined as concave-convex waves, saw tooth or embossing anti-skid surface or with anti-skid coating Metal Fittings and Fasteners Metal fittings and fasteners shall be made of corrosion-resistant material as much as possible; otherwise, they shall be applied with anti-corrosion treatment. 5 Structural Requirements for Extension Ladder and Single Ladder 5.1 Lengths of Extension Ladder and Single Ladder The lengths of extension ladder section and single ladder corresponding to its normal load shall meet the requirements in Table 1. Table 1 Length of Extension Ladders and Single Ladders Normal load /kg Section Length a /m 90 2~ ~7 4

8 110 2~ ~9 The specified length is applicable to single section in multiple-section ladder The total length of an extension ladder is the total of the lengths of all ladder sections. The total length of an extension ladder formed by two or three sections shall not be higher than 18m. The deviation of the actual measured length (excluding ladder foot or end cap) of each ladder section shall be within ±13mm. 5.2 Width of Extension Ladder / Single Ladder The minimal inside clear width between bottom stiles of an extension ladder shall meet the requirements in Table 2. The inside clear width between two stiles of any section in a single ladder or extension ladder shall not be less than 280mm. As for single ladder with length larger than 3m, the inside clear width between two stiles shall be increased by 6mm while its length is increased by per 0.6m. Table 2 Minimal inside clear width between bottom stiles Total length of extension ladder (L) /m Minimal inside clear width /mm L <L L> Lapping When an extension ladder is extended fully, the lap length of each section and adjacent section shall not be less than the values specified in Table 3. Table 3 Minimal Lapping for Multi-section Ladder Nominal length (L) /m Minimal lapping /m Two-section ladder Three-section and multi-section ladders L <L <L <L Retainer An extension ladder shall be equipped with forced retainer to ensure the lapping specified in Table 3, and the lapping shall not be limited by only pulley wheel positioning. 5.5 Guide piece When a guide piece is used to interlock sections, the length of the guide piece along the stile shall not be less than 32mm. 5.6 Locking piece As for section equipped with locking piece, the permanent marking indicating "This section is forbidden to split for use" shall be used or permanent connection locking piece shall be used to prevent the section shifting out if the locking piece results in the cancelling of the first -level rung. The permanent connection locking piece shall a structure that can be demounted out by only cutting, drilling or similar forced method. 5.7 Ladder Foot Anti-skid ladder foot (fixed on the stile bottom side) or corresponding equivalent 5

9 anti-skid measures shall be used for bottom section of single ladder or extension ladder. The reinforcer for the ladder foot shall enable the anti-skid piece rotate free, so that the anti-skid piece can face at the ground correctly again when the ladder is inclined as the predetermined use condition. 5.8 End Cap End cap or equivalent measures to cover sharp edge and burr shall be used on the following positions, besides on stile top: a) The pieces above shall be used on the bottom side of all stiles of the top section or the middle section when the top section or middle section moves on front of the bottom section; b) The pieces above shall be used on the top side of all stiles of the top section or the middle section when the top section or middle section move at back of the bottom section; The length of the end cap (if any) extended to the stile top shall not be higher than the stile depth. The end cap shall meet the strength requirement of the ladder; if its material is not anti-corrosive, the end cap shall be applied with anti-corrosion treatment. 5.9 Cable and Pulley Wheel On the precondition of not reducing the strength of rung or stile, the extension ladder may be equipped with cable and pulley wheel (firmly connected with the ladder). The fastening measures for fast pulleys shall ensure the rung meets the test requirements of The cables used for pulley wheels shall meet the following requirements: a) Its diameter not less than 8mm; b) The cable shall have an ultimate tension of 2490N. 6 Structural Requirements for Stepladder 6.1 Stepladder Length The length of metal stepladder corresponding to its normal load shall meet the requirements in Table 4. Table 4 Stepladder Length Normal load /kg Stepladder length /m ~ ~ ~ ~ The stepladder length shall be meet the requirements specified in 6.1.1, the maximum length of a stepladder or trestle ladder shall not be higher than 6m, and the allowable tolerance of a ladder length shall be ±13mm. The length of a metal stepladder shall be measured along the stile, and the measure parts shall include anti-skid pieces of tip and ladder foot, and exclude the part (like handrail or guard rail) of the front stile extended out of the top cap. 6.2 Stepladder Width As for stepladder, the minimal inside clear width between two stiles on the top step (or rung) shall not be less than 280mm, and the horizontal contained angle between the stile and 6

10 step (or rung) shall not be larger than Step / Rung Depth The front-back depth of a step shall not be less than 80mm, and the front-back depth of a rung shall be larger than 20mm. 6.4 Stepladder Inclination Angle When a stepladder (front ladder section) separates to the working position, the inclination angle of the font section shall not be larger than 73 and the one of the back section shall not be larger than When trestle ladder or accommodation ladder separates to the working position, the inclination angle of the stile shall not be larger than Step (or Rung) Connection When the stepladder is in working position, the steps (or rung) shall be kept horizontal and parallel with each other (allowable tolerance <= 3mm). When step (or rung) and stile are connected by fasteners, at least one fastener shall penetrate out of the front of each side stile, and at least one fastener shall penetrate out of the back of each side stile. Step (or rung) on bottom side shall be used with bracing reinforcer or equivalent reinforcing piece. 6.6 Ladder Tip At least fasteners penetrate through each side of front stile so that the ladder tip is fixed up. The mode of fastening the back ladder foot to the tip shall enable the hinge rotate flexibly. 6.7 Gantry The fixing of a gantry as a part of stepladder shall enable gantry to fold upward when the stepladder is folded up. When the ladder is 2.4m or shorter, the gantry structure shall enable it to be folded up before the ladder is folded, or to be folded with the ladder simultaneously; the gantry shall extend to the stile facing towards the user when ladder folding. 6.8 Stepladder Back The back transverse bracing of a stepladder may be rung or rundle. 6.9 Ladder Foot Ladder foot shall be made of anti-skid material. The upright projection area of anti-skid surface shall not be less than the projection area of the lower end cross section of the stile. At least two fasteners shall be used to fix the front ladder foot, and at least one fastener is used to fix back ladder foot Spreader (or Locking Piece) A stepladder shall have a metal spreader (or locking piece) as one part with the ladder, to make front and back parts keep an open state. The height from the spreader to the bottom bearing surface shall not be larger than 2m. When adopting two sets of spreaders, the height limitation is only applicable to the lower set. 7 Structural Requirements for Combination Ladder 7.1 Combination Ladder Length Length of combination ladder shall meet the requirements of Table 5. Where the ladder is used as stepladder, the ladder length is measured (along the front rim of the front stile) from 7

11 the ladder foot bottom to the cap top (or to the top step/rung, if without top cap), and the allowable tolerance of the length shall be ±13m. Where the ladder is used as extension ladder, the maximum extension length shall be 900mm less than the sum of the lengths of the two sections of the ladder, and the allowable tolerance hereof shall be ±13mm. Table 5 Combination Ladder Length Normal load /kg Section length /m ~ ~ ~ ~3 7.2 Inclination angle of combination ladder The structure of a combination ladder shall achieve that: when it is used as single-side stepladder and on the open position, the inclination angle of the front section shall not be larger than 73 and the back inclination angle shall not be larger than Width of Combination Ladder The minimal inside clear width between front stiles, measured on top step (or rung), shall not be less than 280mm. The horizontal contained angle between front stile and step (or rung) shall not be larger than 80. The inside clear width between two stiles of extended section or single section shall not be less than 280mm. 7.4 Step (or Rung) When step (or rung) can be used as ladder front and back, the steps (or rung) shall be kept horizontal and parallel, and the allowable tolerance shall be within 3mm. 7.5 Step Depth When used as stepladder, the step depth shall not be less than 80mm. 7.6 Gantry When the gantry and the combination ladder are combined as one and the gantry structure shall be folded as a ladder, the gantry shall be folded up into the ladder. 7.7 Ladder Foot Stile bottom shall be equipped with ladder foot and the anti-skid surface shall not be less than the projection area of the bottom cross section of the stile. 7.8 Spreader (or Locking Piece) A combination ladder shall have a metal spreader (or locking piece) as one part with the ladder, to make front and back parts keep an open state. The height from the spreader to the bottom bearing surface shall not be larger than 2m. 7.9 Retainer When a combination ladder is used as extension ladder, it shall be positioned and locked with reliable device, to make its length not less than the indicated maximum working length End Cap When the stile surface is not coated with nonmetallic material, and end caps shall be used on stile top on both sides of a combination ladder. 8 Operating Requirements 8

12 8.1 Selection Extension ladder, single ladder and stepladder shall be used on single side for only single person. Trestle ladder and accommodation ladder may be used on both sides (front and back) for single person A ladder with proper normal load shall be selected according to the maximum working load in the predetermined service condition and the ladder shall be kept from overload in service In the case of working site has limitation to the length of ladder, shorter ladder shall be used to prevent the sliding of ladder bottom if extension ladder or single ladder is too long to erect at an inclination angle A stepladder with proper dimension shall be selected according to the maximum working height in the predetermined service condition, and the maximum working height is the sum of the highest standing level (height) and the user's height. 8.2 Operation / Use Predetermined service condition Ladders shall be used in the design predetermined service conditions (scope) Unless designed for serving multiple persons, portable ladders shall be ascended by only one person Stepladder shall not be used as single ladder (straight ladder) or used in folded state When a combination ladder is used as stepladder, the user shall not ascend on its back section Ascending and working positions The user shall ascend or work on or close the middle part of step (or rung) The user shall not step or stand on the steps (or rung) higher than the indicated highest standing level of the ladder. The user shall not step or stand on the positions below: a) Stepladder top cap, top step (or rung) of stepladder or trestle ladder, or ladder gantry; b) Back rundle of single-side stepladder Erection inclination angle Extension ladder and single ladder shall be erected at an inclination angle of 75 to the horizontal plane, to realize best anti-skid effect, ladder bearing state and ascender balance condition. The method of erecting a ladder at an inclination angle of 75 to the horizontal plane is: to make the horizontal distance from the ladder bottom side to the wall or top supporting plane is equal to 1/4 of the effective working length of the ladder (i.e. 1/4 length rule) Ladder foot supporting Ladder bottom shall be located on firm horizontal supporting surface. Where there is no adequate measure to prevent sliding, ladder shall not be used on ice, snow or smooth surfaces. When a ladder has no safety shoes, spur, road spike or similar antiskid device, foot plate or similar device may act as foot anti-skid piece. Ladder shall not be placed on unstable base to acquire additional height Top supporting When extension ladder or single ladder is placed by supporting the top, the two stiles shall fit the bearing surface simultaneously. When ladder top is supported by column, lamp post, building or tree trunk for working, single stile support accessary may be used for fixing. 9

13 8.2.6 Avoiding lateral bearing Portable ladder shall not be supported laterally, and the user shall keep the body close to the ladder for working Ladder ascending When ascending a ladder upper and lower, the user shall face towards the ladder and keep touching the ladder on three points (any three points of both hands, and both feet). The user shall not ascend a ladder along a lateral face or from a ladder to another, nor ascend a ladder on a swinging plane In case the extension length is not enough, the user shall re-adjust the ladder after getting down to the ground. While the user is on a ladder, he/she shall not do actions like pushing or pulling the ladder Electrical hazards The user shall take reliable safety measures when the ladder for working is close to electric circuit. These safety measures shall able to keep the user from touching any live un-insulated circuit or conductor (electric shock) Except ladders specially designed for electric circuit working, metal ladders shall not be used in the circumstance with possible contact with live circuit. When the user uses a ladder under a live circuit, the operator (user) shall keep safe distance from the live circuit Non-normal use Ladder shall not be used for the purposes below: supporter, skid-ways, lever, tension rod or central column, gang-board, platform, scaffold plate, materials hoisting device or any other non-predetermined use. Ladder shall not be placed on scaffold to acquire additional height Accessing or leaving ladder on upward plane When a ladder is used to access to a high-level plane (roof or platform), the ladder shall extend over the plane by more than 1m. The ladder shall be fixed into the high-level plane reliably when accessing or leaving the ladder on the high-level plane. The user shall avoid making the ladder tip-over laterally or the ladder foot sliding due to fierce action when accessing or leaving the ladder on the high-level plane Ladder erection and adjustment An extension ladder shall be erected to make its top section (extended section) above the bottom section and the rung lock joggled in place. The top section may be in front of at back of the bottom section, depending on the structure formation. If an extended section has been used as single ladder, the section shall be checked (whether it is assembled correctly, or the locking piece is joggled in place) in the erection The extension ladder shall be adjusted by the user only on the bearing surface (ladder bottom) for the purpose of observing whether the locking piece is joggled correctly. The user shall inspect whether the cable slides along the pulley wheel correctly. The user shall not adjust the ladder length on the ladder top (or locking piece) In stepladder erection, it shall be ensured that the ladder is opened completely, the spreader is locked up and the feet contact with horizontal supporting surface firmly Ladder repositioning The ladder shall not be shifted for repositioning when there is person on the ladder Use in strong static electricity area Specially-designed electrostatic-grounding (anti-electrostatic) metal ladder shall be used 10

14 in strong static electricity area to protect the user from electric shock. 8.3 Maintenance Inspection Ladder shall subject to total inspections whey they are purchased and bought into operation; and they shall subject to total inspection regularly and before use each time after bought into operation. In case of structural failure or other defect(s) causing possible hazards, the ladder shall be discarded as useless or repaired by the qualified technician Turnover and other impact failure After the ladder suffers from turnover or other impact, it shall be inspected whether there is stile jog or bending, or over-bending of step (or rung). Total inspection shall be carried out for all metal fittings, step (or rung), stile connecting piece and component High temperature exposure After exposed to hot temperature (like close to fire), the ladder strength may decrease, so it shall be inspected damage or not, and deflection test, stile lateral bend test and rung torsion test may be carried out for extension ladder and single ladder, so as to ensure they meet the safety requirement before used Corrosive substance If a ladder is exposed to some acid or alkali material, such material may reduce the strength of the ladder due to the chemical corrosion. Please consult the manufacturer or the qualified technician before use Oil and wax The ascending and grabbing surfaces of a ladder shall be kept from easy-skid materials like oil and wax Cable and Pulley Wheel Cable and pulley wheel shall be inspected and tested periodically, to ensure normal operation of them; in case of any wearing or defect, the ladder shall be replaced in time Damaged ladder Damaged or bent ladder shall be marked clearly and disused, and then repaired by the qualified technician or discarded as useless Transportation The ladders, when transported by motor vehicles, shall be supported properly. The supporter should be steel tubes covered with wood or rubber to re reduce wearing and road surface impact; and the ladders shall be kept well contacting all supporters to reduce damage due to road surface impact Storage The ladder out-of-service shall be stored on dedicated placement bracket. The bracket shall provide adequate supporting points to prevent ladder from bending or sagging due to gravity. During the storage, other materials shall not place on the ladder Daily maintenance Metal fittings, wearing parts and other accessories shall be inspected periodically to keep their normal working state. All rotation connections and rung lock gliding surfaces shall be lubricated frequently. If connection bolt or rivet is lost or connection between step (or rung) and stile is loosening, the ladder shall be used after repaired to normal state. Stile bottom anti-skid pieces, in case if excessive wearing, damage or loss, shall be replaced in time. 11

15 9 Test Requirements for Extension Ladder and Single Ladder 9.1 Horizontal Bending Strength Test The test shall comply with the requirements of 9.1.2~9.1.4 and the maximum mean bending deformation between two stiles shall not be higher than the values specified in Table The specimen for level bending strength test shall a whole ladder; the tested ladder is placed on a horizontal position, and the supporting position is 150mm away from the stile end. In the test for extension ladder, the specimen shall be extended to the required minimal lapping and the maximum extension length. Auxiliary measures not increasing ladder strength may be used to keep the locking piece joggled during the test to prevent the extended section moving relative to the bottom section. The supporting bars at both ends are 25mm in diameter; supporting bar(s) at an end or both ends may shift longitudinally along the ladder to make the distance from the supporting point to the stile end point 150mm while the specimen is bent during the test loading period. The test load (or pre-load), by means of loading block 90mm in width, is applied on the rung center on the specimen span center (as shown in Figure 1). The loading block shall be made of the material causing no damage to the loaded position Firstly apply load on the ladder for adjustment, then pre-load the ladder as required by Table 7, and release the load after at least 1min. The relative position of the stile by this time shall be the reference point to measure the deformation The level bending strength test load as specified by Table 7 is applied to the specimen span center continuously for at least 1min. Before and during the application of the test load, the deformations of two stiles shall be measured respectively perpendicular to the ground or other reference plane. Test span Minimal lapping Ascending plane Extended section Lower section Supporting bar Test load Supporting bar (25mm in diameter) Figure 1 Diagram for Horizontal Bending Strength Test Table 6 Maximum Allowable Mean Deformation in Horizontal Bending Intensity Test Maximum working length (the full length minus the minimal lapping) Lw /m Maximum allowable mean deformation Y1 /mm 12

16 Two-section ladder Three-section ladder L w 10 - Y 1 =67L w -93 L w >10 - Y 1 =72L w L w 8 Y 1 =73L w -142 Note: the maximum allowable deformation of a single-section ladder shall be tested by the method for single-section ladder Applied with the ultimate test load as required by 9.1.6, the ladder shall be able to withstand this load and show no ultimate failure The ultimate test load specified as Table 7 is applied on a ladder continuously for at least 1min before releasing the load, and the ladder is checked whether there is ultimate failure or not. Table 7 Horizontal Strength Test Load Normal load /kg Pre-load /N Horizontal bending strength test load /N Ultimate test load /N Deflection test The test shall comply with the requirements of 9.2.2~9.2.4, the maximum bending deformation on the loaded stile side and its deflection angle shall not be higher than the values specified in Table 8. Table 8 Maximum Bending Deformation and Deflection Angle Index Maximum working length Lw /m Maximum bending deformation on loaded stile Y2 /mm Deflection angle α /( ) Extension ladder and single ladder 4 L w 18 Y 2 =21L w -65 α=0.328l w +1.5 Combination ladder 2 L w 6 Y 2 =17.4L w α=0.527l w The ladder deflection angle shall be determined by the distances measure with the following method: a) The maximum outside width of the stile measured on the widest section, W; b) The distances (A and B) from the stile to the ground or other reference plane shall be measured respectively before and after loading the test load to a side stile (on the center of the part between the two supporters). The deflection angle (the included angle between the bottom end face of the two stiles to the horizontal plane) is calculated from the equation (1). B A sinα = (1) W Where, α-the deflection angle; A-The distance from the bottom end face of the loaded stile side to the reference plane; B-The distance from the bottom end face of the unloaded stile side to the reference plane; W-The outside width of the widest section A whole ladder as tested one shall be extended to the maximum working length and 13

17 horizontally placed on two supporters 150mm away from the stile end point (as shown in Figure 2). Auxiliary measures not increasing ladder strength may be used to keep the locking piece joggled during the test to prevent the extended section moving relative to the bottom section. The load is applied on the loading block (90mm wide) on the rung on the center of the span forming by the two supporters, and the loading position center is 45mm away from the inner stile edge. Firstly apply load on the ladder for adjustment, then pre-load 132N for at least 1min before releasing Test loads relative to normal load 90kg, 100kg, 110kg and 135kg are respectively 221N, 245N, 265N and 309N. The test load is applied in the loading position (as shown in Figure 2), and the distance from the bottom end faces of the two stiles to the reference plane shall be measured respectively. The measurement shall be made on the outermost sides of the widest section Repeat the test specified as 9.2.3~9.2.4 on the other side. Test span Minimal lapping Supporting bar Test load Supporting bar Test load Figure 2 Diagrams for Deflection Test 9.3 Inclination load test The test shall comply with the requirements of 9.3.2~9.3.3, the ladder shall be able to withstand the loads specified in Table 9, having no ultimate failure, but the test may cause permanent deformation A whole ladder as tested one shall be extended to the maximum working length and placed as shown in Figure 3: the ladder top is supported by the vertical plane and the ladder bottom side is supported by the horizontal plane. The inclination angle between the ladder to 14

18 the horizontal plane is 75. The loading method shall be to make the test load uniformly distributed on the lowest rung in the extended section above the ladder lapping part, and both ends of the loading position shall keep 3mm~6mm to each inside of the two stiles. Table 9 Inclination Load Test Load Normal load /kg Test load /N The test load specified as Table 9 is applied vertically downwards on the lowest rung in the extended section above the ladder lapping part continuously for at least 1min before releasing the load, and the ladder is checked whether there is ultimate failure or not. 15

19 Test load Figure 3 Diagrams for Inclination Load Test 9.4 Metal fitting load test The ladder subjecting to the test specified in 9.4.2~ shall not have permanent deformation or test failure The tested ladder shall be a whole ladder or a shorter specimen satisfying the testing conditions. When testing a whole ladder, the extended section shall be extended to the minimal extension that the ladder extends out of the first-level rung when the ladder is in the minimal working length. The shorter specimen (length) shall include the extension ladder bottom section and a part of the extended section with all metal fittings The ladder is placed to form an inclination angle of 75 to the horizontal plane and to make the two lock joggled. The loading method shall be to make the test load uniformly 16

20 distributed on the lowest rung in the extended section above the ladder lapping part, and both ends of the loading position shall keep 3mm~6mm to each inside of the two stiles. The test load specified as Table 4 is applied vertically downwards on the ladder continuously (as shown in Figure 4) for at least 1min before releasing the load. And the ladder is checked against if there is permanent deformation or test failure. Table 10 Metal Fitting Test and Single Lock Test Loads Normal load /kg Metal fitting test load /N Single lock test load /N Single-lock load test The lock on each side shall be able to withstand the test specified in 9.5.2~ and have no permanent deformation or test failure; after the test, the other components of the ladder may have permanent deformation and the loaded rung shall be able to continue support the test load after loading although the rung has permanent deformation The tested ladder shall be a whole ladder or a shorter specimen satisfying the testing conditions. When testing a whole ladder, the extended section shall be extended to the minimal extension that the ladder extends out of the first-level rung when the ladder is in the minimal working length. The shorter specimen (length) shall include the extension ladder bottom section and a part of the extended section with all metal fittings The test ladder is placed to form an inclination angle of 75 to the horizontal plane and the lock on a side is demounted off. The loading method shall be to make the test load uniformly distributed on the lowest rung in the extended section above the ladder lapping part, and both ends of the loading position shall keep 3mm~6mm to each inside of the two stiles. The test load specified as Table 9 is applied vertically downwards on the rung in the extended section above the ladder lapping part (Figure 4) continuously for at least 1min before releasing the load, and the ladder is checked whether there is test failure or not. Repeat the test specified as 9.5.2~9.5.3 on the lock of the other side. 17

21 Test load Ladder Foot Figure 4 Diagrams for Metal Fitting Test and Single Lock Test Loads 9.6 Rung strength test The test shall comply with the requirements of 9.6.2~9.6.3, the ladder shall be able to withstand the test loads, having no ultimate failure. The permanent deformation of rung shall not be higher than the value specified in Table The specimen shall be taken from the wildest position of a ladder, including at least three levels rungs. When using a specimen with three levels rungs, the test load shall be applied on the middle rung. When a single ladder or section is used as specimen, the test load shall be applied on the third or fourth rung, counted from the ladder bottom The specimen is placed to form an inclination angle of 75 to the horizontal plane, the test load specified in Table 11 is applied on the rung center by means of loading block 90mm in width for at least 1 min (Figure 5), and the ladder is checked whether there is ultimate 18

22 failure or not; the maximum permanent deformation shall be measured. When the rungs are of multiple structures or made of multiple materials, the rung of each structure and made of each material shall respectively subject to the test above. Table 11 Rung strength test Normal load /kg Strength test load /N Maximum allowable permanent deformation W/ W/ W/ W/100 Note: W refers to the clear width of the rung inside the stiles. /mm Rung/stile shear strength test load Rung strength test load Plumb plane Loading block Horizontal plane Figure 5 Diagrams for Rung Strength Test and Rung/Stile Shearing Strength Test 9.7 Rung and stile shearing strength tests After tested as required by 9.7.2~9.7.4, the stile and the stile-rung connecting piece shall not have ultimate failure The tested ladder shall be a section with at least three levels rungs The ladder is placed to form an inclination angle of 75 to the horizontal plane. The test load equal to 3 times of the normal load is applied on the loading block 90mm in width, and the loading block is placed on the stile of the middle rung (closer to a stile side) (Figure 5); the test load is applied for at least 1min before releasing it and the ladder is checked whether 19

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