Safety Net Product Quality Analysis and Enterprise Status Quo

The safety net is a kind of protective equipment for preventing fall injuries. It can be used for all kinds of construction sites, especially high-rise buildings, and can be completely enclosed. It can effectively prevent people and objects from falling, prevent fire caused by welding sparks, reduce noise and dust pollution, achieve civilized construction, protect the environment and beautify the city. It has been widely used at home and abroad.

At present, there are mainly three types of safety nets widely used in China: safety flat nets, safety nets, and dense-view security nets. The flat plane of the safety net is placed parallel to the horizontal plane or at a certain angle with the horizontal plane to catch falling people or falling objects. The installation plane of the safety net and the dense mesh safety net is perpendicular to the horizontal plane and used to surround the plane. Aerial work surface, blocking people or falling objects. The dense-mesh safety net also has the effect of preventing the operator from using a smaller tool to drop the victim.

In 1988, the former Ministry of Labor and Personnel promulgated the “Implementation Rules for Production Licenses for Special Labor Protective Products” and began to officially incorporate labor protection products that directly threaten personal safety and health into production licenses. At present, AQSIQ is responsible for the issuance of safety net production licenses and quality supervision, and the State Administration of Work Safety is responsible for safety production licenses and labor safety certification.

Safety net quality and industry status

(a) product quality. The production process of flat net and vertical net is usually raw materials→drawing→bonding→retarding→woven net (mechanical or manual)→finishing→examination→packing→storage→sale; the production process of dense-eye safety net is usually Raw materials→drawing→weaving (mechanical)→sewing→stucking→testing→packing→storage→sales; the key link is drawing and weaving.

In the 1950s, Pingnet and Lien were mainly using natural fibers such as cotton, hemp and brown, and gradually used chemical fibers after the 1960s. However, the level of product quality was not uniform and the specifications were varied, causing great inconvenience in use. . In 1983, it began to organize the establishment of safety net standards, which well standardized the safety net product market. The product specifications tend to be unified and the quality greatly improved. With the rapid development of the economy, the quality requirements of safety nets have become higher and higher, and standards have been continuously revised. However, the quality of products has never been interrupted.

The compact mesh safety net is a fall protection product used by developed countries in the world in the early 1980s, especially in the construction industry in Japan and the United Kingdom, and has formulated and implemented corresponding product standards. This kind of product entered the Chinese market in the late 1980s. Compared with the traditional safety nets and grids, the dense-mesh safety net has a high degree of mechanization, high production efficiency, easy control of product quality, relatively stable quality, etc. The advantages, especially its flame-retardant properties, penetration resistance, dust-proof, and beautifying work environment, are unmatched by safety flat nets and safety nets. At present, the dense-meshed security network has become the mainstream product in various types of safety net products, and it almost replaces the traditional safety net.

At present, Pingnet and Lientech mainly evaluate 13 items such as tether spacing and length, rib spacing, side rope breaking strength, net rope breaking strength, tendon breaking strength, flame retardant performance and impact resistance performance; Li-net products have 12 items including breaking strength, breaking elongation, trapezoidal tear strength, eye opening buckle strength, flame retardancy, penetration resistance, and impact resistance. Through many years of national product quality supervision, spot checks and commissioned inspections were analyzed:

1. The net ropes, side ropes, and ribs of flat nets do not reach the breaking strength. The GB 5725-2009 standard requires that the side ropes have a breaking strength of ≥ 7000N and have enough strength to fix the net; the net ropes have a breaking strength of ≥ 3000N, which can effectively prevent people from falling and being torn; the strength of the tendons is ≤ 3000N to prevent them from falling. Being injured by sinews, it plays a necessary buffer. The first is that enterprises reduce the diameter of side ropes and net ropes in order to reduce costs, and secondly, the structural design is unreasonable and causes unqualified.

2. The impact resistance of the flat net is not up to the standard. The test method is to use a steel ball with a diameter of 500mm and a mass of 100kg to simulate the human body falling from a height of 7m. The test result requires that the net rope, rib rope, and tether do not break, and the test weight does not touch the ground. If this safety performance fails, it will not be possible to prevent the human body or objects from falling in the sky and ensure the safety of construction workers.

3. The breaking strength of the dense-mesh safety grid * failure to break the project. GB 5725-2009 standard requires A-class network breaking strength × elongation at break ≥ 60kN · mm, B-class network breaking strength × elongation at break ≥ 50kN · mm. This index is to assess the anti-scratch ability of the network, but also can detect the quality of raw materials, in general, this indicator is unqualified, the product raw materials used in inferior materials.

4. The impact resistance performance of the compact mesh safety net is unqualified. This safety feature is used to block people, sight, natural wind, splashes, and uncontrolled small objects. The test method is to use a steel ball with a diameter of 500mm and a mass of 100kg to simulate the impact of the body falling down. The drop height A is 1.8m and the B grade is 1.2m. The test results require that cross-section items should not be penetrable or have obvious damage.

5. The flame-retardant performance of the compact mesh safety net is unqualified. The test of this project adopts the vertical combustion test, requiring that the longitudinal and lateral renewal and smoldering test pieces are not more than 4s. If the flame-retardant performance is unqualified, once a partial fire occurs, it will ignite a piece of the safety net, causing fire and injuring people and objects, thereby causing a safety accident in construction. There have been many accidents of this kind, causing great adverse social effects. Most of the reasons are that the company adds insufficient flame retardant during production or the mixing is not uniform when the flame retardant is added. The detection found that the flame retardant performance of the safety net was affected greatly by the heterogeneity of the sample, and the flame retardant performance of different parts of the same net body was different, which greatly affected the determination of the test results and brought about fire safety hazards.

(b) Status of the company. Safety nets have low production input thresholds and low technical content. As a special labor protection product production license management product, there are currently more than 200 enterprises in the country with an annual production value of 1.5 billion yuan. According to the national spot check and investigation, the status of the company is summarized as follows:

1. Safety net manufacturers are mainly concentrated in three provinces: Shandong, Anhui, and Fujian, accounting for more than 60% of the total number of companies, and more than 95% are small-scale enterprises with an annual output value of less than 5 million yuan. The scale structure of the industry is irrational. In addition to eliminating several large enterprises, the rest are small-scale enterprises. There are no medium-sized enterprises. Small-scale workshop-type enterprises have a wide distribution, and the technology, personnel, and risk resistance are poor, and there are many hidden risks of quality and safety.

2. Safety nets are intensive products that require more personnel. They are viewed from the personnel of the company. The current level of education of the employees is low, more than 90% are junior high school and below, and there are few technical personnel such as engineers, and the personnel flow is large. Many part-time employees cannot guarantee the stability of product quality.

3. Under the low level of quality management of enterprises, the implementation rules for production licenses for special labor protection articles clearly require impact test stands, tensile testing machines (accuracy: ±1%), sand bags (100kg), piercing test frames, and through bars ( 5kg), vertical burner (accuracy: 0.1 seconds) and other equipment for factory product quality inspection. Viewing from the actual adjustment, the factory inspection generally pays insufficient attention to the lack of full-time inspection personnel and the factory records are confusing. Few have passed the ISO9000 quality management system certification.

4. The general production technology of enterprises is lagging behind. The main manifestations are: insufficient equipment automation, low level of personnel skills, relatively poor production environment, little investment in technology development, and only a few patents on exterior design. Product development.

5. There is not enough understanding of the standard for the company. The mixed use of the old and new standards in the implementation of the standard, and the phenomenon of non-division of the A and B levels occurs from time to time. In addition, some safety nets with names such as “safety nets” and “dust nets” have appeared in the market to evade supervision and inspection and are distributed to construction sites for use.

6. Individual companies use unqualified or recycled materials to produce products and the quality is difficult to guarantee. Even companies that have not obtained legitimate production licenses and blindly invest in production disrupt the market order.

Countermeasures and Suggestions

In response to the current product quality and the current state of enterprise development, the following countermeasures and recommendations are proposed: First, raise the threshold for production licenses, strengthen the approval system for equipment, personnel, and the environment, and strengthen supervision and management. Inspecting and cracking down on unlicensed production enterprises, safeguarding the legitimate rights and interests of certified companies, and safeguarding production and market order. The second is the production and use of safety net products, design-to-manufacture, market circulation, and use, as well as multiple management departments. As the division of labor of management departments is different, the management links are disjointed, and the quality of production is monitored. Well, the poor quality of the market and the products used have not yet reached the monitoring effect. It is suggested that the relevant departments can jointly supervise and make it a whole and ensure the quality of products is consistent. The third is to strengthen the implementation of product standards and production supervision and management. Spot checks found that the implementation of some products is not enough standards, the implementation of the old standards or the implementation of new standards, the quality of non-compliance, should strengthen the standard publicity and implementation of inspections. At the same time, it strengthened the supervision and spot checks of the national products and local supervision and spot checks. The fourth is to increase the supervision of circulation and use. On the one hand, the use of inferior products is eliminated, leaving potential safety hazards; on the other hand, there is no market for production companies to produce inferior products. Fifthly, the relevant local parts should strengthen the support of production enterprises so that enterprises can be continuously improved in management, technology and personnel, and have the ability to expand scale and develop new products. Guide and regulate production and establish industrial parks. (China Fiber Inspection)