In the early 21st century, a liquid ammonia tanker truck at a fertilizer plant in a certain county in Shandong Province suddenly rupt the flexible hose connecting the tanker truck and the liquid ammonia storage tank during unloading, causing a large amount of liquid ammonia to leak. The accident resulted in 4 deaths, more than 30 people being poisoned, and more than 3,000 people being urgently evacuated and relocated. It is a typical accident caused by problems with the flexible hoses used in liquefied gas loading and unloading.
According to the investigation, during the regular inspection of special equipment at liquefied gas filling stations, inspection agencies and personnel often focus on inspection and testing of liquefied gas storage tanks, residual gas and liquid tanks, and filling metal pipelines, while the inspection of loading and unloading hoses, are part of the safety accessories of the filling system, is often overlooked. Most of the loading and unloading hoses do not meet the quality standards and are low products from the market. In use, they are easily exposed to the sun or eroded by rain and snow, leading to rapid aging, corrosion, and cracking and frequently bursting during the unloading process. This issue has attracted high attention from national special equipment safety supervision agencies and inspection agencies. Currently, the state has improved industry standards.
Safety performance requirements:
The liquefied gas filling station tanker loading and unloading hoses should ensure that the parts in contact with the medium can withstand the of the corresponding working medium. The connection between the hose and the two ends of the joint should be firm. The pressure resistance of the hose should not be than four times the working pressure of the loading and unloading system. The hose should have good pressure resistance, oil resistance, and non-leakage performance, should not have deformation, aging, or blockage issues. Before the product leaves the factory, the manufacturer should conduct tests on the tensile strength, tensile elongation at break, low-temperature bending performance, aging coefficient, interlayer adhesion strength, oil resistance, weight change rate after medium exposure, hydraulic performance, leakage performance of the hose and its components. The hose should not have any abnormal phenomena such as bubbles, cracks, sponginess, delamination, or exposed. If there are special requirements, they should be determined through consultation between the buyer and the manufacturer. All loading and unloading hoses should be composed of an inner layer made of synthetic rubber resistant to the corresponding liquefied gas medium, two or more layers of steel wire reinforcement (including two layers), and an outer rubber made of synthetic rubber with excellent weather resistance. The outer rubber layer can also be reinforced with a fabric auxiliary layer (for example: one layer of high-strength line reinforcement plus an outer protective layer, and an additional layer of stainless steel wire protective layer can also be added).
Inspection and usage requirements:
The hydraulic test of the loading and unloading hose should be carried out at least once a year at 1.5 times the pressure of the tank, with a holding time of no less than 5 minutes. After passing the test, a gas tightness test should be conducted on the and unloading hose at the design pressure of the tank. Normally, the loading and unloading hoses of tanker trucks at filling stations should be updated every two years for frequently filled stations, the hoses should be updated annually. When purchasing new loading and unloading hoses, users should choose products with a product qualification certificate and a certificate issued by the quality supervision department. After purchase, the hoses must be inspected and approved by the local special equipment inspection agency before they can be put into use If the loading and unloading hoses carried with the tanker truck are used for unloading operations, the technical director or owner of the filling station must first check thefied gas tanker truck use certificate, driver’s license, escort’s license, filling record, annual regular inspection report of the tanker truck, and the inspection certificate the loading and unloading hose, and confirm that the tanker truck, personnel, and hose qualifications are all within the validity period before allowing the unloading operation
Think of danger in times of safety, and nip potential problems in the bud! In recent years, safety accidents in industries such as food,, and chemical engineering have occurred frequently. Although there are reasons such as improper operation by producers and old equipment, the issue of low-quality accessories cannot be ignored! an indispensable fluid conveying accessory in various industries, hoses are bound to usher in a future of “quality” in the trend of standardization and equipment upgrading
Post time: Oct-30-2024