Steel Pipeline pickling methods can be divided into groove type pickling and circulating acid, the cycle can be divided into online circulation pickling and pickling line the outer loop.
Trough pickling method is already installed pipe or tube removed, segmented on chemical pickling tank dipping, after passing through the technical processing and then transported to the construction site, to restore the original installation state.
Pickling line cycle is in place pipe has been installed in order to constitute a hose coupling loop, with corrosion resistant chemical cleaning fluid into the inner loop cycle washing. This method can not dismantle good piping has been installed, but the circuits must avoid hydraulic cylinders , valves and other components. Pickling line the outer loop is some short tube or pipe fittings should not constitute a loop at the mounting location removed, local loop recycling pickling connected with hoses and fittings.
For example: pickling speed, good effect; acid tank does not require large-scale and specialized workshops; reduce pipeline from repeated disassembly and handling , shorten cycle piping, reducing the possibility of contamination of the pipe again and again by rusty; pipeline can be used welded connections, reducing flanges, fittings, bolts and other connectors; reduce project cost. However, recycling pickling process more complicated, pickling quality inspection is also more difficult, once operational errors will cause acid leak accident, so technical management requirements more stringent. Pipeline loop pickling applicable to a large number of centralized, high cleanliness requirements pipeline project; for some larger diameter, shorter shorter pipeline project, using slotted pickling more appropriate.
Pickling quality requirements
Pickling pipes usually inorganic acids such as sulfuric acid, hydrochloric acid and phosphoric acid. Both ensure medias clear wall oxide, rust, scale, and can not re-generate corrosion and rust over walls ; pickling process have a reasonable processes and strict rules to ensure that each part of the inner pipe surface thoroughly and evenly pickling clean and the inner wall of the residual acid, residual water and suspended solids all drained.
Pickling process
(A) type of trough dry hydrochloric acid pickling indignant: pickling → pickling → neutralization and passivation finished.
(2) phosphoric acid trough pickling: Pickling Preparing → pickling finished product.
(3) type of loop hydrochloric acid pickling: Composition loop → leak → degreasing → pickling → washing → in the second pickling and passivation → drying → finished rust.
