Discussion on the design life specified in the drawings
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In a series of acrylic projects, we are the manufacturer and provide the construction drawings； There are also engineering drawings provided by the engineering company. We calculate based on the design life specified in the engineering drawings (15 years) to prepare the construction drawings. But later, the user requested an increase in the design life to 20 years; we felt that this should be the responsibility of the engineering company, not the manufacturing plant. What do you think?
Now, a life cycle has been established for the management of related equipment; the service life of these devices must be managed in accordance with the design life specified in the drawings, and devices that have exceeded their designed lifespan are not allowed to be used anymore. Therefore, the end-users wish to set the design life as long as possible. As a manufacturing factory, do you only have the capability to manufacture products without having the qualifications for designing drawings? Since equipment drawings are to be produced, it’s of course up to you to consider the service life of the equipment! The engineering company is required to design the system for a period of 20 years as per the owner’s requirements; as the manufacturer, you certainly need to take equipment design into consideration. Of course, if it’s an engineering company that provides you with the equipment drawings and asks you to manufacture according to those drawings, then you don’t need to worry about anything other than carrying out the construction as per the drawings.
This post was last edited by letitbe on 2018-3-28 at 16:47. The design life is related to the corrosion rate; even if the engineering company provides the engineering drawings, when the service life changes, it is the responsibility of both the company’s process and static equipment specialists. Typically, engineering companies prepare the design drawings and construction drawings in accordance with the unified regulations set for that particular project. These regulations cover various design parameters and specify detailed requirements regarding the service life of different types of equipment. Such unified regulations are established at the beginning of the project and function as a kind of corporate standard. Engineering companies use these regulations along with process data sheets to create the design drawings; after selecting suppliers through processes such as cost estimation and quotation requests, the manufacturing suppliers then produce the construction drawings based on those design drawings. The construction drawings and calculation documents also need to be sent back to the engineering company’s various departments for a VPC review to determine whether they meet the requirements, ultimately leading to an AP or AN decision. Therefore, it is the responsibility of the engineering company to handle such changes, as it involves altering the contents upon which the design standards are based
You decide on the corrosion allowance yourselves, after all it’s your own design drawings.
If, due to the age of the equipment, the corrosion margin increases, the wall thickness also increases. Therefore, the additional cost should not be borne by the manufacturer. The corrosion margin for pressure vessels is determined based on both the medium used and the materials employed; the process engineering and static equipment teams at engineering companies establish this margin according to the service life required by the client. Equipment manufacturers only need to follow the engineering drawings and the unified regulations for engineering technology.