What gasket is best for 3.5MPa steam pipeline flanges?
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Our factory has newly installed a 3.5MPa steam pipeline, and leaks were detected after it was put into use. All installation and preparation work was carried out in accordance with the relevant requirements before operation; the gaskets used are metal octagonal gaskets made of 0Cr19Ni9 material, while the pipeline is made of 1Cr5Mo. May I ask what kind of materials you use?
Wrapped gaskets can be used, or pre-tensioned butterfly springs can be employed
A graphite gasket with inner and outer rings should be used, HG20610 or HG20631, material 1221.
Well, using graphite gaskets as suggested by the person above works well for dealing with steam and high-temperature condensate; we use graphite in our steam systems, and there have been no leaks so far.
Graphite wound gasket with inner and outer rings, material 1221
Thank you all, but I would like to ask why graphite gaskets are used? What is the difference from metal octagonal pads?
Using gasket tape or octagonal gaskets should work fine; the preload disc spring is optional. If leakage still occurs even with octagonal gaskets, the reason may be insufficient bolt strength; for such pressures, high-strength alloy steel bolts are required, and there are also requirements regarding the surface finish of the flange seals.
A metal wound gasket with inner and outer reinforcement rings will suffice.
Thank you; I agree with your view. It must also be related to changes in temperature and pressure, as well as various external factors. At first, there was no leakage, but after some time, leakage started to occur due to fluctuations in production and changes in pressure. I wonder if such problems would arise if graphite gaskets were used?
In this case, using flanges with male and female sealing surfaces should yield better results.
If leakage occurs with an octagonal gasket, leakage may also occur with a wound gasket. I suspect it might also be related to the routing of the pipes; such pipes should undergo stress analysis, and a reasonable layout should be adopted to reduce deformation at the flanges. I wonder if you have conducted any stress analysis?
Octagonal gaskets have high requirements for both the flange sealing surface and the gasket sealing surface, and they also require a greater pre-tightening force compared to other gaskets.
Rough surfaces and gasketing are more than sufficient
Metal-graphite wound gaskets with inner and outer rings, or flanges modified to have male and female surfaces.