Boiler tube processing methods
【1】Cleaning: Utilizing solvents and emulsions to clean the surface of boiler tubes for the removal of oil, grease, dust, lubricants, and similar organic matter. However, it does not remove rust, scale, or flux from the boiler tube surface. Therefore, it is only used as an auxiliary method in anti-corrosion production.
【2】Rust Removal: Primarily uses wire brushes and other tools to sand the boiler tube surface, which can remove loose or lifted oxide scales, rust, slag, etc. Manual tool rust removal can reach Sa2 level, while power tool rust removal can reach Sa3 level. If the boiler tube surface is coated with firmly attached oxide scales, the tool rust removal effect may not be ideal and may not meet the anchor depth requirements for anti-corrosion construction.
【3】Pickling: Generally, pickling is done using either chemical or electrolytic methods. For pipeline anticorrosion, only chemical pickling is used, which can remove oxide scale, rust, and old coatings, and can sometimes be used as a secondary treatment after sandblasting. While chemical cleaning can achieve a certain level of cleanliness and roughness on the surface, it has shallow anchor patterns and is prone to environmental pollution.
【4】Shot Blasting: Shot blasting is a process that utilizes a high-powered motor to drive the blast nozzle blades at high speed, causing abrasive materials such as steel shot, steel grit, wire segments, and minerals to impact the surface of steel pipes under centrifugal force. This not only thoroughly removes rust, oxides, and dirt but also achieves the desired uniform roughness on the boiler pipes due to the intense impact and friction of the abrasive materials.
After blast cleaning, not only can it expand the physical adsorption of the pipe surface, but also enhance the mechanical adhesion between the anti-corrosion coating and the pipe surface. Therefore, blast cleaning is the ideal method for pipeline anti-corrosion treatment. Generally, shot blasting is mainly used for internal surface treatment of boiler pipes, while blast sanding is mainly used for external surface treatment of pipes. Several issues should be noted when using blast cleaning.
As China's economy continues to grow, long-distance oil and gas pipelines have become a crucial means of energy security. During the anti-corrosion construction of oil (gas) pipelines, the surface rust removal of boiler pipes also contributes to their lifespan. Ensuring the quality of the anti-corrosion coating significantly enhances the process level on the same equipment basis, while reducing production costs.
Boiler tube疏通 aids are beneficial for underwater passages and high-pressure boiler tubes. Generally, during the removal of underground sewage or floodwater, their role is significant and widely advocated. However, what if the underground drainage high-pressure boiler tubes are blocked? Over time, they are buried underground, making the space limited for movement, and the safety not particularly high. Therefore, to address this issue, the疏通 aids for boiler tubes have been developed. They can prevent leakage and damage to compensating joints due to excessive displacement of high-pressure boiler tubes, mainly used for loose coupling of high-pressure boiler tubes that absorb axial displacement and withstand axial pressure thrust within the allowable displacement range. Advantages include large expansion capability and easy, quick installation. Typically, high-pressure boiler tubes are used alongside valves and check valves. Some guidelines only state: "Install high-pressure boiler tubes after valves and check valves." However, the author believes that this rule is far from sufficient. During design, in addition to meeting normal operation requirements, consideration should also be given to maintenance needs. Especially when maintaining equipment and valves, pressure remains in the pipeline after the valves. In this case, high-pressure boiler tubes should be installed after the valves, following the direction of the medium flow, and a maintenance valve should be considered in the pipeline after the high-pressure boiler tubes. For pipelines that are large in diameter and not frequently maintained, from a safety and economic perspective, the high-pressure boiler tubes can be modified to include limiting devices, as shown in the figure. If there are already two valves on the high-pressure boiler tube, it can be installed between them. In the situation shown in the figure, the high-pressure boiler tube should be installed between the electric butterfly valve and the manual butterfly valve. During maintenance, close the manual butterfly valve to inspect or replace the equipment and valves in front of it. High-pressure boiler tubes can also be referred to as expansion joints, compensators, and flexible connectors for high-pressure boilers.
The expansion joint is a new product for connecting pumps, valves, high-pressure boiler tubes, and other equipment, providing a connection with a certain displacement for easy installation. It can withstand the axial pressure of pipelines. This allows adjustments to be made during installation and maintenance based on on-site dimensions, and it also serves to protect pump, valve, and other high-pressure boiler tube equipment during operation. Expansion joints are categorized into several types, including bellows expansion joints, sleeve expansion joints, and rectangular natural compensation expansion joints, with bellows expansion joints being the most commonly used, primarily for ensuring the safe operation of high-pressure boiler tubes. High-pressure boiler tubes are used in two common types: rubber high-pressure boiler tubes and metal high-pressure boiler tubes. China, not only a major agricultural country, is also a mechanical powerhouse, with various factories established in every town. Wastewater from these factories must be disposed of properly without causing pollution or harm to surrounding villages and people. Single flanged high-pressure boiler tubes are made by adding a flange short pipe and a force transmission bolt to a flange loose fit compensation joint. The different compensation amounts refer to the adjustment volume during equipment assembly and disassembly. Once all nuts are tightened, the rigid connection can transfer axial force, thereby protecting valves, pumps, and other equipment. In terms of manufacturing, high-pressure boiler tubes use wire cutting technology, suitable for cutting materials without causing cracks or other harmful defects. Material marking should be transferred before cutting to prevent material misuse. When carbon steel Q235 steel plates no longer require mechanical processing, the oxidation skin, slag, and splashes on the cutting surface should be removed clean, and the surface should be treated flat. The edges of the steel after mechanical shearing should not have cracks, burrs, or missing edges. Carbon steel should not be mechanically sheared when the ambient temperature is below -20°C, and alloy steel should not be sheared when the ambient temperature is below 0°C. After welding, steel plates with cracks resulting from wire cutting should be immediately heat treated, or post-heat treatment should be performed. Dedicated to the development of the high-pressure boiler tube industry for over four decades, Gongyi Xinyue Limiting High-Pressure Boiler Tube Factory, as an enterprise in the development of Gongyi's limiting high-pressure boiler tube industry, has extensive experience in producing various high-pressure boiler tubes, such as steel high-pressure boiler tubes, stainless steel high-pressure boiler tubes, and sleeve high-pressure boiler tubes, among others. The company also has substantial experience in product installation and maintenance. Below, Xinyue's technical staff will provide a detailed explanation of the maintenance issues related to limiting high-pressure boiler tubes. High-pressure boiler tubes promote the development of the mechanical processing industry, and China has surpassed Germany to become one of the world's largest high-pressure boiler tube equipment markets. The role of the high-pressure boiler tube industry is also becoming increasingly important, even indispensable.
