The composite hose for transporting LNG (liquefied natural gas) or LPG (liquefied petroleum gas) that you mentioned is a special industrial hose with high technology, high performance, and high safety requirements. It is completely different from ordinary rubber or plastic hoses.
Below, I will provide you with a detailed explanation from the aspects of structure, materials, key performance, standards, and main application scenarios.
Core design objectives
To achieve safe, flexible, and durable transportation in environments with ultra-low temperatures (LNG around -162 ℃) and flammable and explosive media, and to withstand certain pressures and mechanical stresses.
Typical Structure and Materials (Stacked Composite)
This type of hose is usually a multi-layer structure, with each layer having its irreplaceable function:
1. Inner lining layer:
·Material: The most commonly used is special stainless steel (such as 304/316L) corrugated pipe. This is the core layer, which provides excellent low temperature resistance, corrosion resistance, and ensures smooth flow of the medium.
·Function: Directly contact with low-temperature LNG/LPG, withstand temperature shock and chemical corrosion.
2. Barrier layer/impermeable layer:
·Material: Polymer film (such as polyamide PA, polytetrafluoroethylene PTFE).
·Function: To prevent gas molecules from diffusing through the tiny gaps of the metal bellows, ensuring the purity and safety of the medium.
3. Enhancement layer:
·Material: High strength synthetic fiber woven layer (such as aramid fiber, polyester) or multi-layer steel wire woven layer.
·Function: To withstand internal pressure, provide the compressive strength and burst pressure of the hose, which is the key to pressure bearing.
4. Thermal insulation layer:
·Material: polyurethane foam, vacuum insulation layer or composite insulation material.
·Function: Especially important for LNG hoses, it greatly reduces external heat transfer, prevents the outer wall of the hose from freezing, avoids cold burns and energy loss.
5. Outer protective layer:
·Material: Synthetic rubber (such as chloroprene rubber) or polyurethane that is wear-resistant, weather resistant, and UV resistant.
·Function: Protect internal layers from mechanical damage (friction, impact), weather aging (sun and rain), and external flames.
Key Performance and Technical Requirements
1. Ultra low temperature flexibility: It remains soft at -162 ℃, can bend, and will not become brittle.
2. Excellent fatigue resistance: able to withstand repeated bending and stretching caused by ship shaking, loading arm movement, etc.
3. High security:
·Anti static: The entire tube must be conductive to promptly dissipate static electricity generated by friction.
·Fire resistance: The outer coating usually has fire-resistant properties and can maintain structural integrity for a period of time in a fire.
·Sealing: Extremely low leakage rate, interface design is safe and reliable.
4. Lightweight and Flexibility: Compared to all metal pipes, the weight is significantly reduced, the operation is more convenient, and the load on connecting equipment is reduced.
5. Pressure level: Depending on the purpose, the working pressure ranges from tens of bars to several tens of bars.
Main international standards
The production and testing of such hoses must comply with strict international standards:
·OCIMF (International Maritime Forum of Oil Companies): The "Guidelines for Oil Pipelines for Ship to Ship and Ship to Shore Transportation" released is an authoritative guide in the industry.
·SIGTTO (International Gas Transport Ship and Terminal Operators Association): has specific recommendations for LNG transportation.
·ISO: Relevant standards such as ISO 28460 (LNG Ship to Shore Transportation).
·EN: European standards such as EN 1765.
·The corporate standards of major oil/energy companies, such as Shell and Total, are often more stringent.
Main application scenarios
1. LNG/LPG ship shore loading and unloading: connecting dock pipelines and ship manifolds is the most typical and demanding application.
2. Ship to ship transfer: LNG/LPG transfer between two ships.
3. Truck/tanker loading and unloading: Connect fixed storage tanks to mobile tankers.
4. Internal transportation of terminals: Short distance flexible connections between facilities such as storage tank areas and gasification stations.
5. Emergency unloading/reloading: a backup pipeline used in emergency situations.
Famous brands and manufacturers
This is a highly specialized market, mainly dominated by several international giants:
·Taike Fluid Control: It has many well-known hose brands under its umbrella.
·Vitry: Very well-known in the fields of petrochemicals and low-temperature fluid transportation.
·Swagelock: Provides high-performance conveying solutions.
·Goodyear: Its industrial hose product line covers this type of product.
·Domestic manufacturers: In recent years, some Chinese manufacturers (such as Shandong Yuelong, Nanjing Chengguang, etc.) have also actively researched and obtained relevant certifications, gradually entering the market.
Selection and usage precautions
1. Certification first: It is necessary to choose products that comply with the latest standards such as OCIMF and SIGTTO and have third-party certifications (such as DNV GL, ABS and other classification societies).
2. Special design: LNG pipes and LPG pipes have different emphasis on insulation design and cannot be simply mixed.
3. Regular inspection: Strictly follow the standards for pre use inspection, regular stress testing, and scrap management. There are usually strict limits on the service life and number of cycles.
4. Professional operation: Operated by trained personnel to ensure that the bending radius is not lower than the minimum requirement, avoiding twisting and excessive stretching.
Summary:
The professional composite hose for transporting LNG/LPG is an engineering product that integrates material science, precision manufacturing, and strict testing. Its value lies in providing unparalleled safety and operational flexibility under extreme conditions, making it an indispensable key component in the liquefied gas supply chain. When selecting and using, safety and compliance must be given top priority.