At what pressure should water lines be engraved on the flange?

I. Main Standards Industry-wide standard: When the pressure exerted on a flange reaches or exceeds 10 MPa (megapascals), it is usually necessary to mark water lines on the flange. This standard aims to identify high-pressure areas visually, thereby enhancing operators’ safety awareness and ensuring that the flanges operate safely within specified pressure ranges. ASME standards: ASME (American Society of Mechanical Engineers) specifies clear requirements in its relevant standards regarding the machining and roughness of flange grooves, but the specific relationship with pressure ratings may vary depending on the standard version and application scenario. ASME standards generally require that the waterline be machined on a lathe and processed in accordance with the specified roughness requirements. HG standards: The HG (Ministry of Chemical Industry) standards also contain regulations regarding the grooves on flanges. For example, the HG20592-97 standard mentions the concept of a water line, but later versions (such as HG20592-09) may have dropped this term, focusing instead on the naturally formed serrated concentric circles or spiral grooves on the sealing surface. II. Relationship between water ripple lines and pressure. Function of water ripple lines: The main functions of water ripple lines on flanges are to identify high-pressure areas, improve sealing performance, and increase the friction coefficient. When the flange is subjected to high pressure, the water ripple pattern provides a better sealing effect and prevents the flange surface from coming loose. Relationship between pressure rating and water ripple lines: Generally speaking, as the pressure exerted on the flange increases, the requirements for sealing performance and safety also rise accordingly. Therefore, engraving water mark lines on high-pressure flanges has become a common practice. However, whether water ripple lines need to be engraved, as well as parameters such as their number, depth, and distribution, must be determined based on the specific flange standards and application scenarios. III. Precautions and processing requirements: When processing the water pattern lines, it is necessary to ensure that the lines are clear, uniform, and of moderate depth. Water lines that are too deep or too shallow can affect the structural strength and sealing performance of the flange. Testing and acceptance: During the acceptance process, it is necessary to check whether the water ripple lines meet the relevant standards and design requirements. This includes observing aspects such as the clarity, uniformity, and depth of the water ripples. Application scenarios: Flange water ripple patterns are mainly used in applications that require high pressure resistance or excellent sealing performance, such as in the petroleum, chemical, and power industries. In these industries, the sealing performance and safety of flanges are of paramount importance; therefore, engraving water ripple patterns has become a common practice. In summary, the standards relating to flange water lines and pressure are primarily determined based on the pressure rating the flange is subjected to. Marking water ripple lines on high-pressure flanges is a common practice to improve sealing performance and safety. However, the specific parameters of the water ripple lines need to be determined based on the particular flange standards and application scenarios. In summary, the relevant standards do not specify exactly at what pressure level water ripple lines must be used, or when they cannot be used.

These days, in China, emphasis is not placed much on the water ripple pattern on flanges. There seems to be a specific term for non-metallic gaskets, while metal gaskets are not given as much emphasis these days.