Some standard content:
JB/T8521-1997
This standard is equivalent to ISO4878--1981 "Synthetic Fiber Flat Braided Lifting Belt". There are several differences in technical content from ISO4878:
According to my country's production practice, annular encapsulated lifting belts have been added; - Five types of lifting belts with extreme working loads have been added; - According to the expansion of the scope of application, the standard name has been appropriately adjusted. This standard shall be implemented from October 1, 1997. Appendix A, Appendix B and Appendix C of this standard are all appendices to the standard. This standard was proposed and attributed to the Beijing Hoisting and Conveying Machinery Research Institute of the Ministry of Machinery Industry. The responsible drafting units of this standard are: Beijing Hoisting and Conveying Machinery Research Institute of the Ministry of Machinery Industry, Xushui Lifting Rigging Co., Ltd. The main drafters of this standard are: Wu Suoqu and Wang Bo. This standard is published for the first time.
JB/T8521--1997
ISO Foreword
ISO (International Organization for Standardization) is a worldwide federation of national standards associations (member units of the International Organization for Standardization). The drafting of international standards is the responsibility of the technical committee of the ISO (). Each member unit can send representatives to participate in the standard-making work. Both intergovernmental and non-governmental units can contact the ISO (). The draft international standard must first be recognized by the ISO Council and submitted to the technical committee to be sent to each member unit of ISO (). After seeking consent, it can be recognized as a formal international standard. The international standard ISO4878 was proposed by the technical committee ISO)/TC38 and passed by the member units in September 1979. The following countries agree
AustraliaIsrael
Belgium
Italy
Spain
CzechoslovakiaNew Zealand
SwitzerlandCyprus
Turkey
Soviet UnionGhanaPortugal
Yugoslavia
The following countries disagree:
FranceGermany
Indonesia
Romania
Bulgaria
UKEgypt
Canada
1 Scope
Machinery Industry Standards of the People's Republic of China
Lifting and slings
Synthetic fiber lifting belts
JB/T 8521--1997
1.1This standard specifies the technical requirements for synthetic fiber (polyamide, polyester, polypropylene) flat woven slings and encapsulated slings (hereinafter referred to as slings) used for lifting and loading and unloading cargoes, and specifies their manufacture, testing, identification and marking. Some important suggestions on use, maintenance and inspection are given in Appendix B (Appendix to the standard) and Appendix C (Appendix to the standard).
2 This standard does not apply to special slings or the following forms of use: 1.2
a) Woven belts are used as slings for bundling goods or handling devices to ensure safety; b) Special slings such as bag slings, net slings (including slings made of several cross-sewn belts), adjustable slings (including slings with adjustment buckles in the middle of the belt) when the sling width is less than 25mm or greater than 320mm; c) Non-woven flat slings, such as extruded belts (with or without fiber cores), single fiber belts, and slings made of ropes or cords;
d) Slings used only for pre-hanging;
e) Tubular slings without filling;
f) Belts made of cut fabrics. 2 Referenced standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard was published, the versions shown were valid. All standards are subject to revision. Parties using this standard should explore the possibility of using the latest versions of the following standards GB321-80 Priority numbers and priority number systems
GB3291-82 Textile terminology Textile materials, textile products General part GB/T4146--84 Textile terminology Chemical fibers part GB6529-86 Standard atmospheres for conditioning and testing textiles ISO17-73 Guide to the application of priority numbers and priority number systems ISO) 1833-77 Textiles-Quantitative chemical analysis of synthetic fibers ISO2307--90 Ropes-Testing of physical and chemical properties 3 Definitions
This standard adopts the following definitions.
3.1 Sling: A flexible element used to connect lifting tools and cargo when loading, unloading and lifting cargo. Note: Basic slings are single slings or endless slings used to measure the ultimate working load (see Figure 5) and finished slings or sling components actually used (in some cases it is the same as the basic sling, while in other cases, its shape is knotted or derived or composite). 1) When using narrow and thin slings, the most important thing to be careful of is that the slings are prone to become fragile due to wear or knotting during use. 2) Rope: A fabric with a diameter of not less than 4mm. It is usually made of 3~~4 thick ropes intertwined or overlapped, and it can be with or without a core. Approved by the Ministry of Machinery Industry of the People's Republic of China on March 4, 1997 and implemented on October 1, 1997
JB/T 8521- 1997
3.2 Flat woven slings: Made of woven belts, some with end pieces. 3.3 Braided belts: A part of a sling, made of one or more braids that can be used to bear load forces. 3.4 Seam: A method of sewing a belt itself or several belts together, which is sewn with fiber threads that move back and forth horizontally.
3.4.1 Non-load-bearing seams: The seams that connect several belts together do not bear the load-bearing force of the sling. 3.4.2 Load-bearing seam: The end of the belt is sewn together to form a soft loop or a ring-shaped sling, or a metal end piece is installed. The load-bearing seam bears the load-bearing capacity of the sling.
3.5 Encapsulated sling: A sling that surrounds the load-bearing core in an annular shape and is encapsulated in a sheath. 3.6 End piece: A metal piece installed at the end of the sling. 3.7 Reinforcement of soft loop: When the end piece is installed at the end of the belt, a layer of reinforcing material is added, and the reinforcing material is sewn to the seam of the belt. 3.8 Protective cover: A component woven from leather or other materials that protects the belt but does not affect the load-bearing capacity of the sling. 3.9 Soft loop: A loop formed at the end of the belt. The loop can be installed with an end piece or used directly for hanging. The inside can be reinforced according to the method of 3.7.
Fan-flat soft loop: A soft loop formed by folding the belt back without twisting it and sewing it to the belt itself (see Figure 1). 3.9.1
Figure 1 Flat soft loop
3.9.2 Reverse eyelet: An eyelet formed by folding the tape back and rotating it 180° and then sewing it to the tape itself (see Figure 2). It is not allowed to split the end of the tape into two equal parts along the length direction (see Figure 3). Figure 2 Reverse eyelet
Figure 3 Split eyelet
3.9.3 Folded eyelet: An eyelet formed by folding a part of the tape, sewing the two sides of the tape together or sewing the end of the tape to the tape itself (see Figure 4).
Figure 4 Folding eye
3.10 Effective length: The distance between the two supporting points of the sling when the sling is tightened by hand in a plane without any obvious tension in the sling (see Figure 6, Figure 7 (a) and Figure 10 for details). 3.11 Sling breaking force: The maximum force of the test load that the sling can withstand during the inspection. Expressed in 10N. 3.12 Safety factor: The ratio of breaking force to maximum effective force. For flat woven slings and encapsulated slings, the minimum safety factor is 6. 1) Content added according to national conditions.
JB/T 8521
3.13 Maximum effective force (MFU): The maximum force that a basic sling is allowed to bear, expressed in 10V.
Sling breaking force
3.14 Ultimate working load (WIL.L.): The maximum mass that a basic sling is allowed to bear in a vertical state, expressed in kg or 1 (see Figure 5). When expressed in kg, it is equivalent to 1.02 times the maximum effective force.
Figure 5 Ultimate working load
3.15 Lifting method factor (M): A correction factor that affects the load-bearing capacity due to different hanging methods, used to calculate the maximum safe working load.
3.16 Maximum safe working load (SWLmx): The mass that can be borne under normal use conditions, that is, without considering possible extreme conditions such as high heat, friction, chemical effects, etc., expressed in kg or t. SWLmax= WLLXM
Where: SWLmax—maximum safe working load, kg(t); WLL—limited working load, kgt):
Lifting method coefficient.
3.17 Sling bearing capacity: the maximum safe working load caused by the vertical action of the cargo, expressed in 10N (the proportional relationship between the sling bearing capacity and MFU is the same as the proportional relationship between SWImx and WLI). 3.18 Test force: The force applied to check the performance of the sling before use, expressed in 10N. The test force is equal to twice the maximum safe working load.
3.19 Test load: The load on the sling and end pieces during the test, expressed in kg or t. The force applied is equal to the test force (see 3.18).
4 Types of slings
Note: The attached figure only gives examples of some slings. 4.1 Single sling with soft loop: It consists of a strap with a loop sewn at each end (see Figure 6). Effective length
Figure 6 Single sling with flat soft loop
4.2 Single sling with end pieces: A sling with an end piece at each end of the strap (see Figure 7). 283
JB/T 8521
(a) Two end pieces are the same
(b) Two end pieces are different, and can be used as the end piece of a single sling
4.3 Compound sling: A sling composed of two or more belts of the same width placed side by side. The belts have a common end piece, and the edges of each belt are connected to each other (see Figure 8).
(a) Double-row sling
Soft stitching
(b) Three-row sling
Compound sling
4.4 Multi-layer sling: It is composed of two or more layers of the same belts overlapped in the longitudinal direction (see Figure 9). A section
Multi-layer sling
4.5 Annular sling: One end of the sling is sewn together with the other end, or the sling itself is woven or looped into a ring without sewing (such as encapsulated sling) (see Figure 10).
Effective length
(a) Sewn sling
Instructions for use:
1 Figure 10b is added according to national conditions.
Figure 10 Annular sling
Effective length
(b) Encapsulated sling\
5 Technical requirements
5.1 sling
JB/T 8521-
Slings are only allowed to be woven from continuous fiber yarns. 5.1.1 Material
The belt can be made of one of the following materials: a) Polyamide (nylon): high tenacity, continuous multi-fiber line; b) Polyester: high tenacity, continuous multi-fiber line; 1997
c) Polypropylene 2): high tenacity, continuous multi-fiber line. To ensure the stability of polypropylene, avoid the influence of high heat. 5.1.2 Weaving
The belt should be woven with fabric without any obvious defects. All threads should be made of the same material during the weaving process. The weaving method should ensure that the force applied to the belt is equivalent to the maximum effective force. The width does not decrease by more than 10%. 5.1.3 Width
The standard width series is as follows:
25, 35.50, 75, 100, 150, 200, 300 mm. a) The tolerance of weaving width of strap is:
When the width is ≤100mm, it is ±10%;
When the width is >100mm, it is ±8%.
b) With the consent of both parties, the strap can be selected with non-standard width, but the requirements of other parts must comply with the provisions of this standard. 5.1.4 Thickness
When the sling is composed of several straps, the thickness of each strap should be the same. The surface of the strap can be protected by an appropriate protective layer. 5.1.5 Coloring and other treatments
The strap can be colored or uncolored. The strap can be surface treated to enhance wear resistance. Whether it is a colorant or pigment, or a coating or covering, it should be guaranteed to be non-toxic to humans and organisms. Note: Coloring and other treatments (immersion, coating) should not affect the strength of the strap. 5.2 Sewing of slings
5.2.1 Non-load-bearing seams and load-bearing seams should be sewn with the same high-quality thread as the strap material to facilitate the inspection of the seams. Each layer is allowed to use threads of different colors from the tape. The strength of the load-bearing seam after sewing should be similar to that of the tape. 5.2.2 The degree of damage caused during the sewing process should be minimal. The seams should be flat, the seams pass through the surface of the tape, and no seams protrude from the surface (except for the end joints). "Chain sewing" should not be visible on any side of the tape. When sewing, the seams should leave a distance from the width edge of the tape. For tapes with a thickness of no more than 10mm, 2~4mm from the width edge of the tape is left unsewn; for tapes with a thickness of more than 10mm, 4~8mm is left unsewn.
5.2.3 The seams must have a return seam of at least 25mm at the beginning and end. One defect (such as misaligned seams, missing seams, broken threads, etc.) is allowed within the 100mm sewing length. Each defect can be re-sewn to compensate. 5.2.4 If the cut tape is not pre-treated, the ends of the tape should be treated to prevent loosening, but the adjacent seams should not be damaged. When the hot melt method is used, the ends of the belt do not need to be "seam-fitted". If the belt has been pre-impregnated, it is only necessary to simply "seam-fit" the ends.
5.3 Soft ring
Any type of soft ring should not reduce the load-bearing capacity of the sling. The inner length of the soft ring L (see Figure 11) is as follows: 1) For the specific composition of the material, refer to IS () 18332) For details of this term, refer to GB3291, GB/T4146285
JB/T 8521--1997
a) When the belt width is 25 or 35mm, it is 100mm; b) When the belt width is 50-150mm, it is 3 times the belt width; c) When the belt width is 150mm, it is 2.5 times the belt width. Figure 11 Soft ring inner length L
When the soft ring is used for direct hanging, the diameter of the support shall not exceed 1/3 of the soft ring inner length. If the belt width is 75mm, the soft ring should not be directly connected to the hook ring for suspension; if the belt width is ≤75mm, the soft ring can be directly connected to the hook ring for suspension, but the curvature radius of the hook ring should not be less than 0.75 times the belt width.
5.4 End pieces
Each All end pieces should be installed in soft rings, and the inner diameter of the soft ring should not be less than 2.5 times the diameter or thickness of the end piece passing through it. 5.4.1 Material
is metal but not cast. It should have good mechanical properties and corrosion resistance, aging resistance and fatigue resistance within a temperature range of 30~+80C. Its breaking strength should not be less than 4 times the ultimate working load of the sling (or greater, if the relevant national standards have requirements for this). The maximum load-bearing capacity of the end piece shall not be less than the load-bearing capacity of the sling. The manufacturer shall provide guarantees in accordance with Chapter 9 before supplying the goods. Ensure that the end pieces of the slings provided can meet these requirements.
The end piece shall not be subjected to permanent deformation force, which is not Less than 2 times the load-bearing capacity of the sling. Note: Except as specified above, other materials and manufacturing methods of end pieces are not allowed unless they can be proven to be feasible. 5.4.2 Shape
All surfaces should be processed to remove sharp edges and corners to avoid damaging the belt. When connecting the belt to the end piece, it should be ensured that the force during suspension is evenly distributed over the entire width of the belt. When the belt width is >75mm, convex or circular end pieces cannot be used; when the belt width is ≤75mm, it can be used. However, its radius of curvature shall not be less than 0.75 times the bandwidth. 5.4.3 Reuse of end pieces
An intact end piece is removed from a damaged sling and installed in Before using a new sling, it must be inspected by a professional technician and can only be used if the following conditions are met:
a) It meets all the requirements of this standard;
b) No damage or defects are found. However, if it has been subjected to a load twice its maximum safe working load, it cannot be reused. 5.5 Ultimate working load
5.5.1 For the ultimate working load value (WL.L) of the basic sling (in kg or t), use the R10 priority number system\select according to Table 1. 5.5.2 The ultimate working load given in the table is applicable to the basic sling. Appendix A gives the coefficients and maximum safe working loads of different lifting methods.
5.6 Safety factor
For the sewn straps or encapsulated straps of the sling, the minimum safety factor is 6, while the safety factor for the metal end parts is 4.6 Test
The breaking test should be carried out under the standard atmospheric pressure in accordance with (GB6529, otherwise all tests can be carried out in a normal environment only after the agreement of both parties.
The appearance and size inspection should be carried out before the test. 6.1 Breaking test
The breaking test is to obtain the maximum force that the sling with sewn straps can withstand before breaking. 1) R10 priority number system see (1321 and 1S17. 286
6.1.1 Sampling
JB/T 8521--1997
Ultimate working load of basic slings
10 000
16 000
20 000
25 000
a) For slings of the same type (the same weaving method, width, material, end piece and stitching type) with a weight of less than 5000kg (excluding 5000kg), one piece is randomly selected as a sample from every 250 pieces in a batch; for slings of 5000-10000kg, one piece is randomly selected as a sample from every 100 pieces in a batch; for slings of 12500-31500kg, one piece is randomly selected as a sample from every 50 pieces in a batch. When the length of a batch of slings cannot be tested on general equipment, the sample can be a sling that is exactly the same as the batch and has a suitable length for testing.
b) Take three pieces from each batch of end pieces as test specimens for testing. Welded end pieces should be tested piece by piece at 2 times the limit working load. 6.1.2 Test method
Place the specimen on a testing machine or a special device and apply force. For annular slings, the force is applied to the belts on both sides. The minimum force applied is the maximum effective force of the sling until the breaking force of the sling is reached. The testing machine shall comply with ISO2307 and shall meet the following requirements: a) The maximum reading on the dial of the testing machine shall not exceed 10 times the breaking force of the tested sling; b) The force applied to the tested sling shall make the sling elongation rate 6% to 10% of the original length, but not more than 250mm/min. The speed of force application should ensure that the specified breaking force is reached within 60s±10s; c) When testing slings with soft rings on the testing machine, a test rod should be used. The diameter of the rod makes the angle between the two sides of the soft ring not exceed 20°; when testing annular slings, the diameter of the test rod shall not exceed 100mm or 10% of the actual length of the sling (the smaller of the two) and ensure that the test rod does not touch the seam.
6.1.3 Judgment rules
If the applied force meets the specified requirements, the sample and the batch of products are considered to be qualified. If the sample fails when the applied force is less than 90% of the breaking force, the whole batch of slings shall be downgraded for use. If the sample fails when the applied force is less than the breaking force but greater than 90% of the breaking force, two more samples can be selected from the same batch of products for retesting. If these two samples meet the specified requirements, the whole batch of products is considered to be qualified, otherwise the whole batch of products is downgraded for use.
6.2 Verification test
When the buyer requires, a verification test can be carried out. The sample is subjected to a force equal to twice the maximum safe working load at the speed specified in 6.1.2 and maintained for at least 1 minute, and then checked for damage, such as breakage, splitting of the seams (referring to the belt part), any permanent deformation, cracks or other defects (referring to the end piece).
7 Marking
7.1 The marking of the sling shall include the following: Instructions for use:
1] 12.5~~31.5t in the table is added according to national conditions 287
a) Belt material;
b) Maximum safe working load;
c) Manufacturer or supplier;
d) Year and month of manufacture,
Other marking requirements shall be agreed upon by the buyer and seller. JB/T8521---1997
7.2 The above marking content must be durable and can be marked on a label or directly on the sling. The marking should not affect the safety of the sling. The material brought can also be identified by the color of the label itself. Label color
a) Polyamide (nylon): green
b) Polyester:
c) Polypropylene:
8 Label
To facilitate inquiry and ordering needs, the labels of this standard include the following: a) Name: Synthetic fiber lifting belt for lifting slings; h) Type: according to 3.9 and Chapter 4;
c) Material: according to 5.1.1 and 5.4.1;
d) Ultimate working load: according to 3.14 and Appendix A; e) Safety factor: according to 3.12 and 5.6;
f) Color of belt: if required:
g) Further treatment of belt: if required; h) Standard number
9 Report of compliance with this standard
9.1 When the user requests, the supplier shall provide the user with a report of compliance with the standard to indicate that the product meets the requirements of this standard and indicate the date. The report shall also include the following: a) supplier company and address; b) sling label (according to Chapter 8); c) trademark (when possible). When the components of a batch of slings involved in the supply are exactly the same, the manufacturer only needs to provide a general report. If the goods are provided to dealers, the dealers shall provide each user with a report including various information including the general report. 9.2 If a test certificate is required, a test certificate may be issued based on the results of the test in Chapter 6 agreed by both parties. 288
JB/T 8521-1997
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000 012 The above-mentioned markings must be durable and can be marked on labels or directly on the slings. The markings should not affect the safety of the slings. The materials used can also be identified by the color of the label itself. Label color
a) Polyamide (nylon): green
b) Polyester:
c) Polypropylene:
8 Label
To facilitate inquiry and ordering needs, the labels of this standard include the following: a) Name: Synthetic fiber lifting belt for lifting slings; h) Type: according to 3.9 and Chapter 4;
c) Material: according to 5.1.1 and 5.4.1;
d) Ultimate working load: according to 3.14 and Appendix A; e) Safety factor: according to 3.12 and 5.6;
f) Color of belt: if required:
g) Further treatment of belt: if required; h) Standard number
9 Report of compliance with this standard
9.1 When the user requests, the supplier shall provide the user with a report of compliance with the standard to indicate that the product meets the requirements of this standard and indicate the date. The report shall also include the following: a) supplier company and address; b) sling label (according to Chapter 8); c) trademark (when possible). When the components of a batch of slings involved in the supply are exactly the same, the manufacturer only needs to provide a general report. If the goods are provided to dealers, the dealers shall provide each user with a report including various information including the general report. 9.2 If a test certificate is required, a test certificate may be issued based on the results of the test in Chapter 6 agreed by both parties. 288
JB/T 8521-1997
Published. 06
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000 012 The above-mentioned markings must be durable and can be marked on labels or directly on the slings. The markings should not affect the safety of the slings. The materials used can also be identified by the color of the label itself. Label color
a) Polyamide (nylon): green
b) Polyester:
c) Polypropylene:
8 Label
To facilitate inquiry and ordering needs, the labels of this standard include the following: a) Name: Synthetic fiber lifting belt for lifting slings; h) Type: according to 3.9 and Chapter 4;
c) Material: according to 5.1.1 and 5.4.1;
d) Ultimate working load: according to 3.14 and Appendix A; e) Safety factor: according to 3.12 and 5.6;
f) Color of belt: if required:
g) Further treatment of belt: if required; h) Standard number
9 Report of compliance with this standard
9.1 When the user requests, the supplier shall provide the user with a report of compliance with the standard to indicate that the product meets the requirements of this standard and indicate the date. The report shall also include the following: a) supplier company and address; b) sling label (according to Chapter 8); c) trademark (when possible). When the components of a batch of slings involved in the supply are exactly the same, the manufacturer only needs to provide a general report. If the goods are provided to dealers, the dealers shall provide each user with a report including various information including the general report. 9.2 If a test certificate is required, a test certificate may be issued based on the results of the test in Chapter 6 agreed by both parties. 288
JB/T 8521-1997
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