Regarding bolt tightness
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This post was last edited by Gunao Biao Kun on 2011-11-5 at 12:16. Dear all: Recently, the flange bolts on several pipelines in one area of our factory have been frequently coming loose. They get tightened once a week, but still become loose afterward. This happens to both 4-hole and 6-hole flanges. The temperature of the pipeline when it is filled with medium on a regular basis (sometimes with water, sometimes with steam) varies frequently (30-90). Vibration occurs in the pipeline during medium flow (not very severe), and no anti-loosening washers are used for the bolts. Please share your opinions and analyze the reasons and solutions.
What size bolt? How is it tightened?
Address the cause of bolt loosening appropriately: if the pipeline vibrates excessively, consider adding buffer supports, spring supports, or dampers to the pipeline. For the pipeline bolts, the shanks can be made longer and back caps used, thereby employing a double-nut fastening method.
I wonder what the temperature of your steam is? Is it necessary to heat-tighten the bolts when hot water and steam alternate?
I wonder what the temperature of your steam is? Is it necessary to heat-tighten the bolts when hot water and steam alternate?
It’s just an ordinary 4-inch carbon steel double-headed bolt; this kind of situation has not occurred before
Reply to 1#: I am kind-hearted. Suggestions: 1. Replace the bolts and nuts. 2. Use the correct tightening method to achieve a reliable preload effect. 3. Cut off the flange and weld it directly (I would like to mention this in particular: we **prefer flange-based connections in our designs; in fact, welding is a very good connection method with high reliability)
You can try adding spring washers and spare nuts.