Acid leakage from the flange of the purification acid pipe
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The acid purification pipes in our factory tend to leak acid, and this has been the case for many years. We have tried products from several different manufacturers as well as services provided by various maintenance companies, but none of these solutions have resolved the problem; leaks at the flanges still occur frequently
What is the material of the pipeline? Are pressure and temperature suitable? Is the leakage at the flange due to the weld or the gasket?
Made of fiberglass reinforced plastic, with a pressure of 0.3 MPa and a temperature range of 40–60 degrees. Leaks occur at the flange surface starting from where the gaskets are located; even after tightening the screws, leaks persist. Tightening them further doesn’t help. It worked for some time after the flange was repaired, but leaks started again later on
What acid is it, what is the concentration, what is the temperature, and what is the pressure?
It seems to be a gasket issue; try using a PTFE gasket (the one currently in use is probably a rubber gasket)
What acid? The gasket used is incorrect, and are there any sealing grooves on the flange?
It’s 2–18% dilute sulfuric acid, with a temperature of 40–60 degrees. Initially rubber gaskets were used, but switching to PTFE gaskets improved things slightly; however, leakage still occurs. There are sealing grooves on the flange
Fiberglass-reinforced plastic expands significantly when heated; it is recommended to tighten the bolts and nuts again when passing materials through it.
That makes sense; I share the same view
If it doesn’t work, then replace the pipe; constant leaks are a hassle and affect normal production as well as safety
It is recommended to switch to a steel-lined PO/PE material; after pressing it with rubber gaskets, production remains stable, and there are no issues over several years of use. Of course, PTFE gaskets are even better. Frequent shutdowns of the liquid flow, as well as fluctuations in temperature along the pipelines, could also be causing your current issues due to thermal expansion and contraction.