Compare EPS to Acid Pickling – Process and Product

As a process for descaling hot rolled strip, EPS directly competes with acid pickling.  More mills, picklers and processors are choosing EPS because of its demonstrated advantages over acid pickling. The evidence of those advantages is provided throughout this web site, but the table below provides a helpful summary of the most important ones.

As a product, EPS pickled strip is used successfully in every application – process, fabrication or finishing operation – where an acid pickled product is used. Put another way, EPS product is completely interchangeable with acid pickled product. However, EPS offers fabricators and manufacturers many advantages over an acid pickled product. This has been demonstrated through exhaustive laboratory testing and countless real-world applications documented throughout this web site. The second table below provides a helpful summary of the most important EPS product advantages.

EPS vs. ACID PICKLING - PROCESS COMPARISON
EPS PICKLINGACID PICKLING
Economics• 25% lower capital cost
• 20% lower variable operating cost
• 30% lower installation cost
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Building• 50% less floor space, therefore
• Smaller, lower cost building
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Environmental• no environmental impact - no special permits
• all inputs & waste products are safe
• all-electric process - stable energy costs
• hazardous process - special permits required
• toxic, corrosive acid is a pervasive danger
• use natural gas to heat acid tanks - volatile prices
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Pickling Different Grades• fully pickles all grades - no change in setup or operation
• 15 - 20% speed loss** for high carbon, alloy steel
• 25 - 30% speed loss** for AHSS
• fully pickles stainless - no change in setup
• some grades too difficult or require special measures
• 50% speed loss** for high carbon, alloy steel
• 60 - 75% speed loss for AHSS
• stainless requires HF acid and dedicated line
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Consistency of Descaling Process• always consistent: real-time feedback controls line speed for desired level of descaling for all grades• inconsistent: line speed is predicted , so over/under pickling often results. Some AHSS pickled twice.GET DETAILS >
Line Stop/Start Flexibility• stopping line mid-coil no problem - no surface impact
• line restart takes 1 minute
• stopping line mid-coil can cause pickling stains and over-picklingGET DETAILS >
Tension Leveling• effective tension leveling is built into the EPS Coil Line. Shape improvement with no added cost or space.• tension leveling involves adding bridle rolls at significant additional cost and line space.GET DETAILS >

**  relative to average pickling speeds for low carbon steel

EPS vs. ACID PICKLING - PRODUCT COMPARISON
EPS DRY PRODUCTACID PICKLED HRPO PRODUCT
Resistance to Rusting• dry EPS surface is rust inhibitive - no oil or coating• acid pickled surface rusts quickly - oil film needed.GET DETAILS >
Oil on Surface• oil not needed, but can be oiled if customer requires• oil required to prevent rusting
• oil presents health hazard to fabrication workers
• oil fouls shop, equipment, gloves/uniforms
• oil must be stripped off for painting/coating
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Fabrication Operations• laser & plasma cuts up to 60% faster
• stronger welds and reduced toxic welding fumes
• enhances performance & economics of stamping, rollforming and other operations
• the oil film on HRPO presents many problems in sheet metal fabrication processesGET DETAILS >
Surface Quality• EPS creates a more uniform surface topography
• EPS mitigates common surface defects like pitting, scratches, roll marks, rust, silicon streaks, pickling stains
• acid does not alter surface topography
• acid can create new problems - pickling stains
• acid makes some surface defects worse - silicon streaks, pitting
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Paint Performance• EPS surface optimized for paint performance
• better paint adhesion, superior appearance
• paint pre-treatment can be 'leaner'
• oil inhibits paint adhesion, so pre-treatment stage(s) must remove all oilGET DETAILS >
Downstream Processing• EPS presents a superior surface for galvanizing
• the EPS surface is optimized for cold reduction
• annealing dry EPS keeps oil from fouling annealing bell, vent lines
• the oil film on HRPO must be stripped off prior to most downstream processesGET DETAILS >

Our customers see great value in the EPS dry surface compared to a traditional pickled and oiled surface. They have been able to increase laser cutting speeds by 20 to 30% and on top of that, can skip shot blasting prior to painting.

Timo Vierimaa

President, Peak Metals

Hot immersion galvanizing of EPS did not present any issues and was processed at 25 tons/hour. Its spangle was more uniform and, compared to acid pickled coils, the EPS coil’s spangle was smaller and more homogeneous.

Franco Rachello

Project Manager, Acerias de Colombia

My top EPS user does laser cutting, press brake, welding and powder coating – no trouble performing any process on EPS. From CQ to Grade 50, anything he does works as well with EPS as it did with P&O.  For him,  EPS completely replaces P&O.

Steve Morrow

General Manager, Southern Metals Supply

We can’t run HRPO on our structural mill – oil causes the tubing to slip in our mill. So we formed the tubes in black and then had them pickled outside with 3 week lead time. So using EPS dry takes 3 weeks off delivery time and saves the freight.

Large multi-location Tube Producer who sources hot roll primarily from US Steel