Shotblast and Oil vs Pickle and Oil

Often times people will use the terms Shotblast and oil interchangeably with Pickle and Oil, however, they are different in their impact on the steel.  The similarities would be that both methods remove mill scale from the steel substrate surface and then have a rust inhibitor oil applied to forestall any immediate rusting of the steel.  The differences are much more numerable… first would be the impact on the steel surface.  In the shotblast and oil process there are tiny abrasive particles that bounce upon the surface of the steel that generate heat on the substrate and dust as the abrasive is pulverized along with the mill scale.  Unfortunately, as the shotblast and oil abrasive is removing the mill scale its also removing some of the steel substrate which results in an altered steel surface profile and can look like tiny craters.  With the batch pickling process, we fully submerge the steel into our pickling vats to dissolve and remove the mill scale from the steel.  We add special chemical inhibitors into our pickling liquor that stops the dissolving process once the mill scale is removed thus we do not impact the steel surface profile at all.  Since paint layers are getting thinner, the imperfections left from the shotblast and oil process often can be visible in the paint finish, whereas they will not be present and visible after pickling.  Furthermore, in the pickling process, since it is chemical based, there is no heat generation with the steel nor any dust generated that can have serious negative health effects. 

In our Pickling process we use batch immersion for the steel material.  We have special racks that we load all the steel material into before we process. The material is specifically positioned and we are very careful to space the material vertically and horizontally to insure that our chemicals can get to all sides of the material being pickled.  Especially with items like tubing, pipe, angles, channels, etc. in which there are surfaces that are difficult to reach (i.e.  corners, inside of pipe, etc.), since the material is completely immersed in our tanks the fluid can access all areas to remove the scale and other impurities on the steel surface.  With shot blasting the abrasive material can not always get into corners, edges, or the inside of pipe/tubes, etc.  In addition, with shot blasting, often a ghost image of the conveyor system is left on the steel that would not be present in the pickling process.  

With Batch Pickling, unlike shot blasting, we can process large quantities of steel in a relatively short time span.  In expedite situations we can even turn around material in a day!  As we know in business time is money!  Unlike shotblasting and oiling, the pickling process is a relatively green process for removing mill scale from steel.  We do not employ a lot of energy consuming equipment in our process nor do we generate hazardous dust that can lead to Silicosis.  We employ special filtration equipment to maintain and lengthen the life of our chemical tanks and use special water filtration equipment to keep any wastewater manageable for further water treatment.  Our spent pickling liquor , Ferrous Chloride, is used again in the water purification industry!  We are always researching ways to decrease our waste stream and recycle our materials.