Container flange water line
Thread Content
Why are the water ripple patterns on the sealing surface of the heat exchanger head flange beneficial for sealing? From various perspectives, everyone has analyzed why the presence of water ripple lines on container flanges results in better sealing.
The RF surface has water ripple lines; the bolts are tightened to press the gasket in place, creating a tortuous seal for better performance
Steel pipe flanges, gaskets, and fasteners – HG20592-1997, Table 6.0.1 on page 11: Types of sealing surfaces. Note: For raised-face flanges with a PN ≤ 4.0 MPa, non-metallic flat gaskets, PTFE-coated gaskets, and flexible graphite composite gaskets can be used; tight-groove water lines can be machined on them, and the sealing surface code is RF(A). Table 6.0.1 Sealing surface types, page 291 of HG20615-1997. Note: For raised-face flanges with PN≤5.0 MPa, non-metallic flat gaskets, PTFE-lined gaskets, and flexible graphite composite gaskets can be used; tight-groove water lines can be machined on them, and the sealing surface code is RF(A). In other words, other types of sealing surfaces cannot have precision grooved water lines machined. Using rigid gaskets such as metal wound gaskets results in an even worse sealing effect for the tightly grooved water lines. What is referred to here are \"raised-face steel pipe flanges\"; in accordance with the JB/T81-94 standard, raised-face steel pipe flanges with a nominal pressure of PN0.6~2.5 Mpa do not have \"water ripple\" patterns fabricated on their sealing surfaces. Because under operating conditions at this pressure level, this type of flange fully meets the operational requirements.
The function of the sealing water line is primarily to enable the soft gasket to form a wavy pressure distribution area after compression, thereby enhancing the sealing effect. However, the use of asbestos gaskets is decreasing nowadays, and the role of sealing water lines is diminishing
Since the gasket is soft, the flange surfaces squeeze the gasket material into these grooves, thereby providing a sealing effect.
The new standard no longer requires the processing of water ripple lines
The new standard no longer imposes any requirements on the water ripple pattern, but it does have specific requirements regarding the roughness of the sealing surface; it cannot be too smooth. Soft gaskets should be used, and when the roughness of the sealing surface is high, increased pressure can easily damage the gasket
This is a requirement of the new standard: attach://1349031.jpg
ASME B16.5 has always required this, and the new domestic standard HG20592 also follows ASME requirements; a fine serrated water line is beneficial for sealing.
The original water ripple pattern consisted of two grooves, while the current roughness features a dense pattern of lines. It was once repaired because the flange sealing surface was too smooth, with a roughness that did not meet the requirements.
The article on this official WeChat account at http://mp.wei*n.qq.com/s/4RBVpIiz3cw9vrsc5xSKqw seems to be quite easy to understand