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This post was last edited by Xin Ruifangxiao on 2025-6-10 at 13:15. An access hole, also known as an inspection hole or viewing hole, is an opening used to enter and inspect the interior of devices such as pipes, storage tanks, and containers; it is one of the important components of industrial equipment. Manholes are widely used in fields such as chemicals, petroleum, food, pharmaceuticals, and textiles. Manholes are usually made of metal or plastic materials, typically have a circular or square shape, and come in certain dimensions and thicknesses. They are usually installed on the side or top of the equipment or container, and covered and protected by a lid or door. By opening the cover or door, staff can access the interior of the equipment to perform inspections, cleaning, repairs, or replace components. https://mp.toutiao.com/mp/agw/article_material/open_image/get?code=NmYyOTJjNzE3NmFmNzYyNDZhZTFlYmViOWEzZjUwMmMsMTY4MjQ5MDc2ODAxMA== There are various types of manholes used in industry, including handholes, cover-type manholes, removable manholes, rotary manholes, and more. Among them, the manhole is the simplest and most basic type; it is usually installed on pipes or equipment to facilitate cleaning and maintenance when needed. Cover-type manholes are commonly used in large equipment and containers; they typically consist of a circular or square cover along with a support frame, and the cover can be easily removed for maintenance purposes. Removable manholes and rotary manholes are even more convenient for use and maintenance. Different types of manholes have distinct characteristics and uses. For example, manholes with lids are commonly used for the maintenance of small pipes and equipment, while large containers and equipment typically use removable or rotatable manholes to facilitate access and maintenance by personnel. https://mp.toutiao.com/mp/agw/article_material/open_image/get?code=MzExMDJmNzk4MWYwZTIwZjVjOTZlZjg2YWY3ZTQ0YjQsMTY4MjQ5MDc2ODAxMA== In industrial production, manholes play a very important role. They can provide an easy way to access the interior of the device, helping staff diagnose and resolve issues more quickly. For example, in the oil and chemical industries, regular inspections and maintenance are required inside the equipment to ensure its safe and efficient operation. Through the manhole, staff can easily access the interior of the equipment to carry out tasks such as leak detection, cleaning, and repairs. Furthermore, manholes can also help workers better control the production process. For example, in the food processing industry, through observation holes, staff can monitor the interior of the equipment at any time to ensure the hygiene and quality of the processing process. In the pharmaceutical industry, manholes can help workers monitor and control parameters such as temperature, pressure, and flow rate during the drug production process. Of course, using manholes also presents some risks and challenges. Since manholes are typically used to access equipment in high-temperature, high-pressure, and corrosive environments, workers need to possess a certain level of safety awareness and skills. Before using the manhole, staff must first understand the environmental conditions and safety regulations inside the equipment, as well as the measures that should be taken to ensure its safety. Furthermore, when opening and closing the manhole, it is necessary to ensure that the pressure inside the equipment is properly released and controlled to safeguard the safety of the workers. For equipment operating in high-temperature and high-pressure environments, it is very important to use personal protective equipment such as protective clothing, gloves, and goggles. In addition, the use of flammable materials and hazardous chemicals should also be avoided to prevent fires and explosions. When performing maintenance and repairs, staff must ensure that the equipment has been shut down and is in a safe state before opening the access panel to carry out the work. In corrosive environments, workers must choose corrosion-resistant materials to manufacture manholes in order to ensure their stability and safety over the long term. Furthermore, when using manholes, it is necessary to avoid spilling corrosive substances inside the manhole and in its surrounding area, in order to prevent dangerous accidents. https://mp.toutiao.com/mp/agw/article_material/open_image/get?code=YjY4NzVhMjY1N2ZlNTk3MGE4YWVjMjQ0OTQ3NzJkYTIsMTY4MjQ5MDc2ODAxMA== In industrial production, the sealing of manholes is also very important; it prevents the leakage and contamination of substances inside the equipment, while at the same time preventing external substances from entering and causing contamination. To ensure the sealing of the manhole, gaskets or seals are typically used to fill the gap between the manhole and the cover. Gaskets and seals are usually made of materials such as rubber, silicone, and polytetrafluoroethylene, which possess properties like heat resistance and corrosion resistance, enabling them to maintain a tight seal effectively. When selecting gaskets or seals, many factors need to be considered, such as operating temperature, pressure, and the properties of the medium. If the selected material is not suitable for the working conditions, it will lead to seal failure, thereby affecting the safe and efficient operation of the equipment. Additionally, the sealing of manholes also requires regular inspection and maintenance. Due to changes in temperature and pressure inside the equipment, gaskets or seals may age, get damaged, or deform, resulting in a loss of sealing performance. Therefore, it is necessary to regularly inspect and replace gaskets or seals to ensure the sealing performance of the manhole. https://mp.toutiao.com/mp/agw/article_material/open_image/get?code=OGQzM2EyMjI4ZGRmZmFhOTViMTc5NTZjMjU4NmY1ZGQsMTY4MjQ5MDc2ODAxMA==Fle*ngSeal® PTFE tape has been successfully applied to the manholes in desulfurization towers. Overall, although manholes play an important role in industrial production, care must be taken when using them, and relevant safety regulations and operating procedures must be followed to ensure the safety of workers and the proper operation of the equipment. At the same time, regular maintenance and inspection of manholes are also one of the important measures to ensure their safe and effective operation.