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Guide to ASTM Stainless Finishes

ASTM (American Society for Materials and Testing) was developed to set standards for chemical, mechanical, physical, and electrical properties of material, as well as testing standards for materials.  ASME (American Society of Mechanical Engineers) includes ASTM standards, AWS (American Welding Society) standards and other nationally and internationally recognized standards as part of a widely adapted design specification for many structures, including pressure vessels.

Apache has substantial capabilities for mechanical and chemical finishing having supplied stainless equipment to hygienic industries for more than four decades.  Passivation, pickle passivation and electropolishing processes and associated ASME testing, and processes are 100% in-house.  
Passivation is the removal of excess iron or iron compounds from the surface of stainless steel by means of a chemical, typically an acid based solution. Unlike pickle passivation, no metal is removed from the surface during the process. The process has little effect on the RA values of the stainless material being passivated.

The ASTM A967 is a passivation standard that applies to the cleaning, passivation, and testing of stainless parts. 

Pickle Passivation is the immersion of the metal in a pickling bath or coating the material with pickling solution such as nitric-hydrofluoric acid. The process removes both metallic contamination and heat-treating scales. Pickle passivated stainless steel has a matte appearance. Apache’s tests have confirmed improvements up to 25% in RA readings on material that has been pickle passivated.

The ASTM A380 is a passivation standard that covers cleaning, descaling, and passivating stainless material and parts. Spec A380 may include a variety of treatments, including precleaning, chemical descaling, degreasing and more. 

Electropolishing is an electro-chemical process that removes surface material from stainless steel.  The process includes immersion of the stainless-steel component into a temperature-controlled bath of electrolytes that are charged with a DC power supply. Electrolytes used in electropolishing are concentrated sulfuric and phosphoric acid solutions.  The finish has a mirror appearance. Apache’s before and after tests have shown improvements in RA smoothness up to 50%; results vary depending on stainless material. 

The ASTM B912 specification outlines the electropolishing process for 200, 300 and 400 series alloys.  Spec B912 may include preparatory cleaning procedures, post coating procedures and rinsing protocols.  Final testing is also stated in the specification to evaluate performance of finish.

In Guide to ASTM & ASME Stainless Finishes, learn about the mechanical and chemical finishing processes to meet ASME, ASTM and other compliance requirements. 

Download Guide

Requirements for the Repair or Alteration of ASME Stainless Pressure Vessels

Whether an accident, environmental damage, or refurbish needs, vessel repair may be necessary at the customer site.  It is important that whoever works on ASME pressure vessels is qualified, certified, and experienced. The National Board, the regulatory commission for ASME, requires an ASME R-Stamp for the repair or alteration of pressure vessels.

Repair areas and welds should be carefully assessed before repair.  Qualified technicians may use die penetrant, x-ray, or ultrasonic devices to inspect welds and surface defects.

If the vessel requires repurposing or refurbishment, qualified ASME engineering professionals must be involved to make sure the changes are compliant with ASME. 

All nozzles and attachments added to the pressure vessel must be ASME compliant.  In addition, there are specific requirements for materials by ASME, including all attachments that are welded to the pressure boundary.

The welding procedure for ASME vessel repair is extensive to include rules for joints, torch cutting, arc gouging, grinding, reinforcement and post weld treatments.

For all repairs or alterations to stainless vessels, it is essential to know the materials and heat treatment requirements. The owner of the vessel, the manufacturer of the vessel, or the National Board (if registered) will have a data report on the vessel which includes a history of all repairs and ASME data for the vessel.

Sufficient time for the proper repair or refurbishment of the vessel is also a requirement.  The tank or vessel needs to be off-line for proper testing, prep, verification, and compliance documentation to be accomplished.  Repair or refurbishment may take a few days to complete, so discuss the plan and process with your repair organization.  Apache provides a realistic timeline estimate after the results of the repair / refurbish assessment. 

Apache Stainless, as a qualified ASME R-Stamp manufacturing organization, will work with the customer, NDE (Non-Destructive Examination) firm (if required) and third-party inspector during the process and will provide the R stamp documentation to the customer and the National Board (NB) when completed.

There are significant requirements for R-stamp approval including:

  • Qualified material documentation
  • Supporting calculations
  • Qualified and certified welder, and welding procedures
  • ASME inspector and witness to R test and attachment of stamp
  • Registering with the National Board.

Apache’s technicians are fully certified ASME welders.  With over 40 years’ experience in vessel manufacturing and continued excellent inspection ratings from ASME auditors, Apache is a solid partner for ASME compliance design, manufacturing, and repair.

Apache Custom Stainless Tanks Support Growing Biofuel Industry for Sanimax

Sanimax, a leading rendering and renewing process company, partnered with Apache Stainless Equipment Corp. to provide stainless steel tanks to support growing production of B100 Biodiesel fuel. The Sanimax facility in DeForest, Wisconsin is dedicated to the processing of 100% renewable Biodiesel fuel. Apache supported their need for increased capacity by supplying one atmospheric stainless tank and three pressure vessels within the past month.

According to IFP Energies, a public sector research and education center for energy, transport and the environment, Americans are taking an interest in alternative fuels. The center’s 2012 report states that USA has been the world’s leading producer and consumer of biofuels since 2007. Sanimax responds to that growth by increasing production capacity.

The most recent custom stainless steel tank supplied by Apache was used for fuel storage. The tank was constructed from stainless steel with exterior insulation and aluminum cladding. The tank increased storage capacity for Sanimax by 30,000 gallons. The 132” diameter, 45 ft. high and 19,000 lb. atmospheric tank was API 650 rated. Apache provided in-house insulation and aluminum cladding of the tank and was shipped via Apache truck.

Apache serves the biofuel industry with many types of specialized tanks, including: distillation columns, evaporators, ASME vessels, API-650 Vessels, clad vessels, custom mix tanks and storage tanks. The Apache facility in Beaver Dam, Wisconsin is fully equipped with machines and processes for shearing, forming, welding, rolling and in-house head making. The company also provides finishing capabilities, including automated mechanical polishing, electro-polishing and passivation. Another facility in Plover, Wisconsin produces carbon steel tanks and equipment.

Apache appreciates the partnership with Sanimax and their cooperation in telling this story!

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