Categorizing levels of sanitary design is helpful to professionals new to compliance regulated industries requiring custom vessels because it bridges communications regarding standards and design requirements.
In hygienic applications, stainless equipment requires a sanitary finish which generally refers to a smooth, scratch-free, non-corrosive finish. The fineness of the finish, which determines its performance, is measured in RA (roughness average). The infographic illustrates the RA of different types of mill, mechanical, and chemical finishes. The smaller the RA reading in microinches (height in millionths of an inch), the smoother the finish.
When collaborating to qualify a project, we define a Base Level Finish as a 2B/Mill, 304 or 316 stainless materials that is pickle passivated. The welds are continuous and crack and crevice-free. This type of finish is paired with a Base Level Sanitary Design and is cleaned manually. Apache’s standard portable vessel line are an example of the base sanitary design and finish level.
A Mid-Level Finish is also composed of 304 or 316 stainless material and involves a secondary process of mechanical polishing greater than 32RA, with final finishing to include pickle or nitric passivation. The welds are continuous, crack and crevice-free, and are also ground flush and polished smooth to a specific RA. Sanitary fittings, mechanical polishing, additional passivation processes and a cleanable design with removable components are categorized as Mid-Level Sanitary Design features.
Providing the smoothest RA readings is an electropolished finish after a series of processes, including mechanical finishing to less than 32 RA, passivation, and nitric passivation, which are common for High-Level Finishes. The base material is 304/316 stainless. The welds are continuous, crack and crevice-free, ground flush and polished smooth to a specific RA designation less than 32RA. The sanitary fittings are also electropolished. Vessels with this level of specifications are typically cleaned automatically.
The specifications, construction and finishing of a vessel is often driven by standards and compliance requirements. All three categories, qualify for ASME UM, ASME U, FDA, 3-A, CRN, PED, BPE.
There are other factors that fall in these base, mid and high-level sanitary design categories, including construction features, processing applications and time to delivery. Download our e-book “Guide to Sanitary Design for Custom Vessels in Hygienic Industries".
When evaluating a custom vessel manufacturing partner for a new project, consider the manufacturing capabilities and experience that support the vessel’s application and sanitary requirements.
All custom design stainless vessels for the food, life sciences, pharmaceutical and health industries require sanitary construction. It is the application and automation that drives the level of sanitary componentry.
In reviewing each new custom vessel project, Apache identifies the sanitary requirements to categorize the vessel into a base, mid- or high-level design. Apache offers a standard line of vessels that qualify for various regulatory compliance agencies. However, these designs are considered a base level sanitary design, especially because the cleaning of the equipment is manual. Apache identifies a mid-level sanitary design vessel as having COP (Clean Out of Place) components.
In the video, a custom vessel is animated to walk through characteristics and examples in the highest and most automated level of sanitary design custom vessels.
High-Level Sanitary Design Characteristics Include:
Processes and application in high-level sanitary design vessels include heating and cooling vessels, mixing and processing tanks, WFI tanks, filtering and R & D lab equipment.
Certification requirements is an important part of the sanitary design criteria. Sanitary design standards include:
3A – A regulation of the design for processing equipment in the food and drug industries. A 3A certificate is proof of FDA compliance.
ASME U and ASME UM - A regulation of the design of boilers and pressure vessels, including traceability of materials, procedures, testing and documentation.
BPE – A standard within ASME that drives equipment design for the bio-processing, pharmaceutical and other hygienic required industries.
In qualifying design, safety, automation other application details, Apache will facilitate the required compliance for the vessel and provide well communicated delivery, cost and approvals required for a successful project.
Stainless Finishes for Hygienic Vessels are measured by an RA (Roughness Average) meter. Manufacturers of custom vessels for life science, health and pharmaceutical industries adhere to strict design parameters to maintain compliance in these industries. The RA is a standard for an average of peaks and valleys on the metal’s surface, measured in microinches. Here is the evolution of stainless material coming to Apache with RA designations as it is transformed into custom sanitary design vessels:
RA > 100 Mill Finish A Mill Finish has an unpolished, dull-gray, matte appearance. This material type is the basis for supply for all stainless-steel flat products as well as the basis for additional finishing operations. It is hot or cold rolled with an RA (Roughness Average) of more than 100 microinches, depending on the gauge of the material.
RA 15 – 40 2B Mill Finish 2B Mill finish is widely used in food, chemical and pharmaceutical equipment applications. It is corrosion resistant and has a typical RA range of 40 (7 gauge) to 15 (16 gauge) microinches.
RA 29 – 58 No. 3 and No. 4 Finish Mechanical polishing achieves these finishes. The No. 3 Finish uses a 120-grit abrasive and has a semi-polished finish with an RA range of 36 – 58 microinches. The No. 4 Finishes uses a 150-grit abrasive and has a polished, brushed surface. The RA range is 29 – 40 microinches.
RA 18 – 31 No. 4A Also identified as No. 4 Dairy Finish, this finishes is required to meet the basic FDA 3-A standards. It uses a 180 grit and has a RA range of 18 – 31 microinches.
< 32 RA Pickle Passivation Pickle Passivation often follows other manufacturing processes including welding and grinding. Also called Pickling, it 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.
Lowest RA Electropolishing Electropolishing is an electro-chemical process that removes surface material from stainless steel. The process includes an immersion of the stainless-steel component into a temperature-controlled bath of electrolyte that is 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/after tests have shown improvements in RA smoothness up to 50%; results vary depending on stainless material.
In the highest level of sanitary design applications the vessel is pickled after manufacturing and polishing, then electropolished.
Vacuum or Pressure closures for small/portable ASME vessels
Many processors come to Apache for a vessel solution in the incubation stage of their business. In some cases, they are looking for help to choose the right kind of vessel that will suit their needs and fit their budget. While Apache provides custom ASME vessels for a range of industries, we also offer a line of standard vessels that often solve what these manufacturers need for their process.
The use of the vessel will determine whether it is a pressurized solution, non—pressurized or vacuum vessel solution.
Vessels that require a minimum of 50 PSI, utilize a pressure closure. Numerous applications, including heating or cooling process, containment, and pressurized dispensing often utilize pressures at or above 50 psi.
It is important to note the safety and ASME requirements for pressure vessels, an ASME UM-mark is required for:
For vacuum requirements or non-vacuum applications, such as a storage vessel or collecting vessel, a vacuum closure may suit the application.
In the video, Nick Buchda, Apache’s Small Vessel Representative, demonstrates vacuum and pressure closures on our standard line of vessels.
Apache has produced stainless vessels with ASME certification for over 45 years, with other accreditations for pharmaceutical, life science and health industries including ASME UM, ASME U, FDA, 3-A, CRN, PED and BPE.
Whether the vessel needs fit a standard vessel, modifications to a standard vessel or a custom solution, Apache has the experience to fulfill a range of critical, sanitary-design vessel solutions.
ASME is a leading developer of codes and standards in the mechanical engineering community. These standards enhance public safety and health as well as promote innovation.
The ASME (American Society of Mechanical Engineers) mark is a single certification marketing to signify the international mark of safety and quality. Recognized worldwide, manufacturers that provide ASME have a rigorous quality program, and a third-party review to authorize the use of the mark.
The U mark certifies that the pressured tanks or vessel conforms to the latest edition of the ASME code and that the pressure vessel has been designed and manufactured in accordance with ASME. All aspects are approved by a Third party ASME Authorized Inspector (AAI). U stamps require an ASME inspector to witness the ASME hydro test.
Companies with a U mark undergo a review with the National Board every three years.
The UM mark certified that the pressure vessel or tank conforms to the latest edition of the ASME code and that the pressure vessel has been designed and manufactured in accordance with ASME. The UM vessel’s designation is related to the size of the tank/vessel.
While the American Society of Mechanical Engineers writes the rules for the new construction of pressure vessels and tank, the National Board of Boiler and Pressure Vessel Inspectors write the inspection code for new and repaired vessels.
The National Board of Boiler and Pressure Vessel Inspectors require a Certificate of Authorization and R stamp for the repair or alteration of boilers, pressure vessels and other pressure retaining equipment.
Apache has been ASME certified for over 45 years. In addition to ASME, Apache is accredited in many other global standards. By setting parameters for quality and compliance, we offer greater value for our custom stainless ASME tanks and vessels.
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