Selection of flange type and pressure class for 31% hydrochloric acid, 40% hydrofluoric acid, and 40% nitric acid
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The project intermediates are 31% hydrochloric acid, 40% hydrofluoric acid, and 40% nitric acid. How should the types and pressure ratings of equipment and pipe flanges be selected? One scenario is where the equipment and pipes are steel-lined with PE ； In another scenario, where the hydrochloric acid storage tank is made of fiberglass, and the hydrochloric acid metering tank as well as the hydrofluoric acid metering tank are made of PP-H, how should the flange type and grade be selected? Another question is whether plastic pipes can be used for these three types of media But for plastic pipes, the flange type is PL; how can this conflict with the regulations be resolved? Another question is: how should the interface flanges for the transfer pumps of these three media be selected? What requirements should be placed on suppliers? Thank you!
For pipelines, plastic-lined pipes with PN16 rating are preferred, using PL flanges with RF sealing surfaces. For equipment and certain pipes where lining is not feasible, metal pipes with appropriate corrosion resistance are used; they are of PN16 grade, and SO or WN flanges can be employed along with MFM sealing surfaces. Corrosion is monitored, and the pipes are replaced regularly.