GB 5725-2009 PDF in English
GB 5725-2009 (GB5725-2009) PDF English
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Standards related to (historical): GB 5725-2009
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GB 5725-2009: PDF in English GB 5725-2009
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 13.100
C 73
Replacing GB 5725-1997, GB 16909-1997
Safety nets
ISSUED ON. APRIL 01, 2009
IMPLEMENTED ON. DECEMBER 01, 2009
Issued by. General Administration of Quality Supervision, Inspection and
Quarantine;
Standardization Administration of the People's Republic of
China.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Terms and definitions ... 5
4 Classification labels ... 8
5 Technical requirements ... 8
6 Test methods ... 12
7 Inspection rules ... 18
8 Marks ... 20
Annex A (Normative) Impact resistance test of safety nets ... 22
Annex B (Normative) Weather resistance of horizontal (vertical) nets ... 24
Annex C (Informative) General requirements for packaging, transport, storage
... 25
Bibliography ... 26
Safety nets
1 Scope
This Standard specifies the classification labels, technical requirements, test
methods, inspection rules and marks.
This Standard is applicable to safety nets used to prevent people or objects
from falling at work heights in buildings.
2 Normative references
The provisions in following documents become the provisions of this Standard
through reference in this Standard. For dated references, the subsequent
amendments (excluding corrigendum) or revisions do not apply to this Standard,
however, parties who reach an agreement based on this Standard are
encouraged to study if the latest versions of these documents are applicable.
For undated references, the latest edition of the referenced document applies.
GB/T 5455, Textiles - Burning behavior - Determination of damaged length,
after-glow time and after-flame time of vertically oriented specimens
GB/T 8834, Fiber ropes - Determination of certain physical and mechanical
properties
GB/T 10125, Corrosion tests in artificial atmospheres - Salt spray tests
GB/T 12903, Personal protective equipment terminology
GB/T 14522, Artificial weathering test method for plastics, coating and rubber
materials used for machinery industrial products - Fluorescent UV lamps
3 Terms and definitions
For the purposes of this document, the terms and definitions defined in GB/T
12903 as well as the followings apply.
3.1 safety nets
a net used to prevent people and objects from falling, or to avoid and mitigate
falling and physical damage
NOTE 1. A safety net is generally composed of net body, border ropes and tie ropes.
3.10 border ropes
ropes that are connected to the net along the edge of the net body
3.11 tie ropes
ropes that secure the safety net to the support
3.12 tendon ropes
ropes that are regularly worn on the mesh body to increase the strength of the
horizontal (vertical) net
3.13 mesh size
distance between two adjacent net rope knots or nodes in horizontal (vertical)
net
3.14 initial sag
sag distance of horizontally suspended safety net due to its own weight
3.15 pre-tension
load that eliminates unnatural wrinkles in the sample before testing
3.16 breaking stress
maximum tensile force measured when the mesh sample is stretched to break
NOTE. The unit of breaking stress is Newton (N) or Kilonewton (kN).
3.17 extension at break
elongation of the sample when it reaches the breaking stress
NOTE. The unit for extension at break is millimeter (mm).
3.18 stretching resistance at unwelded joint
maximum force measured when a joint is torn, when a sample is allied with
pulling force, under the specified test conditions
NOTE. The unit for stretching resistance at joint is Newton (N) or Kilonewton (kN).
3.19 trapezoidal method tearing stress
maximum tensile force measured when a trapezoidal sample is torn when the
sample is stretched
be firmly fixed.
5.2.1.3 There shall be no yarn breakage, hole, deformation and woven defects
in the net body.
5.2.1.4 The round button with hole at each edge of the fine mesh net shall be
firm and reliable.
5.2.1.5 The width of fine mesh net shall be 1.2~2m. The length shall be
designated according to the clause agreed by both parties of the contract but
shall not be less than 2m.
5.2.1.6 Conduct the test according to the methods specified in 6.2.2. The
allowable deviation of mesh and net width is ±5%.
5.2.1.7 The aperture of round button with hole shall not be less than 8mm.
5.2.1.8 Conduct the test according to the methods specified in 6.2.3. The
aperture of mesh shall not be greater than 12mm.
5.2.2 Basic performances
5.2.2.1 Breaking stress × extension at break
Test according to the method specified in 6.2.4. Breaking stress (kN) ×
extension at break (mm) in length, width directions.
- not less than 65kN·mm for class A;
- not less than 50kN·mm for class B.
5.2.2.2 Stretching resistance at unwelded joint
Test according to the method specified in 6.2.5. Stretching resistance at
unwelded joint shall not be less than breaking stress.
5.2.2.3 Trapezoidal method tearing stress
Test according to the method specified in 6.2.6. Trapezoidal method tearing
stress in length, width directions shall not be less than 5% of breaking stress at
corresponding direction.
5.2.2.4 Stress of round button with hole
Test according to the method specified in 6.2.7. Stress of round button with hole
(N) in length, width directions shall not be less than 2.45 × spacing of round
button with hole in corresponding direction.
5.2.2.5 Breaking stress of tie ropes
Apply a pre-tension of (10 ± 1) N on each of the two adjacent parallel nets along
the measurement direction. Then measure the total side length of a continuous
(n≥10) mesh on one of the nets and divide by the number of measured meshes
to obtain the mesh length of the safety net. The result remains one decimal
place.
6.1.4 Measurement of specifications
Use a length measurement device of which the precision is not less than 10mm
to measure the specifications of horizontal (vertical) nets.
Apply a pre-tension of (500 ± 50) N on the side rope in the direction of
measurement. Then measure the side length of horizontal (vertical) nets. The
result remains one decimal place.
6.1.5 Test of rope breaking stress
Randomly remove the net rope, border rope and tendon rope of sufficient length
from the sample net and make three samples according to the requirements of
GB/T 8834 for the test of rope breaking stress. The net rope and the border
rope results take the minimum value, and the tendon rope results take the
maximum value, and the values retain the integer number.
6.1.6 Flame retardant performance test
Randomly remove the network rope, border rope and tendon rope of length
(300±5) mm from the sample net to test according to the method specified in
GB/T 5455. The result remains one decimal place.
6.2 Test method of fine mesh safety vertical nets
6.2.1 General
For the fine mesh net used for testing, if the designed length exceeds 6m, the
length of test sample shall be 6m; if the designed length is less than 6m, it shall
be tested as actual sample. If the designed width exceeds 1.8m, the width of
test sample shall be 1.8m; if the designed width is less than 1.8m, it shall be
tested as actual sample.
6.2.2 Fine mesh net width
In the indoor environment, select 3 consecutive sets of round buttons with hole
in the center of the test sample. Apply 30N of pre-tension to each button.
Measure the distance between the lines formed by the farthest point of the
border rope. If there is no border rope, the center of the buttonhole shall prevail.
The measurement result is accurate to 1mm.
If the net is damaged during the application of pre-tension, the test is deemed
The net body is clamped on the jaw of the other end of the material testing
machine, the clamping point distance is 300mm, the clamping width is 300mm,
and the drawing is performed at a speed of (200±20) mm/min. Read
dynamometer readings.
6.2.7.3 Test results
Calculate the average value in the length and width directions as test data. The
test result unit is N and is reserved to the integer position.
6.2.8 Breaking stress of tie ropes
6.2.8.1 Sample
Prepare the sample according to the method specified in GB/T 8834. The
quantity is 3 pieces.
6.2.8.2 Test steps
Test according to the method specified in GB/T 8834.
6.2.8.3 Test results
Calculate the average as test data. The test result unit is N and is reserved to
the integer position.
6.2.9 Penetration resistance
6.2.9.1 Sample
Extract two (1 × 1) m samples along the edge of the net in the length and width
directions, respectively. The sample shall have one side for the complete net
side.
6.2.9.2 Test steps
Place the sample in a (1 × 1) m frame in a natural state. Place it obliquely at
30°, and the net side is mounted on the top. Release a test rod at a height of 1
m from the center of the net. The test rod has a diameter of 50mm and a mass
of (5±0.2) kg. The end face is the smallest cross section of the test rod and the
corners are sharp. The rounded corner is smaller than R1.
6.2.9.3 Test results
Perform visual inspection. If the test rod passes through the net body or there
is a tearing hole through which the test rod can pass, it is considered as a test
failure.
6.2.10 Impact resistance
Net body containing metal wire (fiber) shall be additionally pretreated by salt
spray method (method C).
6.2.13.2.1 Ultraviolet radiation (method A)
The distance between the center of the sample and the bulb shall be (400 ± 20)
mm. The temperature inside the box does not exceed 60°C during normal
operation, and the bulb is a nominal 450W UV high-pressure xenon lamp. The
recommended model is XBO-450 W/4 or CSX-450 W/4. Continuous
illumination is for 260h. Test after placing for 1h.
6.2.13.2.2 Xenon illumination (method B)
The radiant energy of the xenon lamp in the range of (280~800) nm can be
measured. The blackboard temperature is (70±3)°C. The relative humidity is
(50±5)%. Spray water or spray cycle for 18min every 102min. The radiant
energy in the range of the accepted wavelength (280-800) nm is 0.8 GJ/m2.
Test after placing for 1h.
6.2.13.2.3 Salt spray method (method C)
Perform according to the neutral salt spray (NSS) test method specified in GB/T
10125. Test period is 7d.
6.2.13.3 Test results
The aged samples are tested for breaking stress × extension at break,
trapezoidal method tearing stress and penetration resistance according to the
methods specified in 6.2.4, 6.2.6 and 6.2.9, respectively. The results shall
comply with the provisions of 5.2.2.10.
7 Inspection rules
7.1 Inspection type
The inspection is divided into exit-factory inspection and type inspection.
7.2 Exit-factory inspection
The production enterprise shall carry out the exit-factory inspection batch by
batch on the safety net batch produced. Inspection items, individual inspection
sample size, unqualified classification, and determination arrays are shown in
Table 3 and Table 4.
and product structure have significant changes that may affect product
performance;
- when production is resumed after the production has been discontinued for
more than six months;
- cycle check once a year;
- when the results of the exit-factory inspection and the previous type
inspection are quite different;
- when state quality supervision agencies require to carry out the type
inspection.
7.3.2 The sample is randomly selected from the unit that has submitted the
inspection or the third party that has passed the exit-factory inspection. The
number of samples meets the requirements of all test items.
8 Marks
8.1 Marks of horizontal (vertical) nets consist of permanent mark and product
manual.
8.1.1 Permanent mark of horizontal (vertical) nets.
- reference to this Standard;
- product certificate;
- product name and classification mark;
- manufacturer name, address;
- date of production;
- marks or signs required by relevant laws and regulations in other countries.
8.1.2 The manufacturer shall provide product manual in the minimum package
of the product, which shall include but not be limited to the following.
- precautions for installation, use and dismantling of horizontal (vertical) nets;
- storage, maintenance and check;
- period of use;
- stop suing under any circumstances.
Annex B
(Normative)
Weather resistance of horizontal (vertical) nets
B.1 Principle
Test the weather resistance of horizontal (vertical) nets by using an artificial
climate accelerated test method that simulates the main factors in outdoor hot
and humid natural atmosphere.
B.2 Test devices
Weatherproof test box meeting the requirements of GB/T 14522.
B.3 Test sample
Take 3 border ropes, 3 net ropes from sample net respectively. Make them into
sample ropes according to the requirements of GB/T 8834.
B.4 Test methods
B.4.1 Test according to the method specified in GB/T 14522.
B.4.2 When using fluorescent UV test, the illumination temperature is 60°C ±
3°C, 4h illumination and 4h condensation shall be selected by illumination and
condensation cycle.
B.4.3 When using the xenon lamp artificial climate test, the blackboard
temperature is 63°C ±3°C, the relative humidity is 65% ± 5%, and the water
spray period is 18min per 102min.
B.4.4 Test period is 14d.
B.5 Determination of test results
The tested sample shall be subject to the breaking stress test according to the
method specified in 6.1.5. The results shall meet the requirements of 5.1.9.
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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