Guest Post- Material Trends for High Purity & Sanitary Applications
By: Ken Kimbrel- Special Alloys Product Manager, VNE Corporation
For almost 60 years, Holland Applied Technologies has been providing customers with the best high purity process products in the industry. Today, we’re excited to share our first guest post, highlighting our newest sanitary fitting product offering, as well as providing an excellent overview of what makes a material corrosion resistant. Enjoy!
For several years stainless steel has been the workhorse processors have used in tough corrosive environments. For the most part, it has performed well. In recent years, however, in many new installations or even repairs to existing process lines, today’s stainless steel doesn’t perform as well in the same application as stainless steel of years past. Additionally, with the advent of newer buffer solutions in the pharmaceutical industry we are experiencing higher than ever chloride levels which attack stainless steel causing pitting and crevice corrosion.
As with all industries, imports, competitive markets and technological advances have enabled and even forced steel manufacturers to become more competitive in the steel making process. The most significant of these advancements impacting the steel industry was realized nearly 40 years ago with the introduction of argon-oxygen-decarburization (AOD) refining. The use of AOD allows the extensive use of scrap metal. In fact, some heats are nearly all remelted scrap metal. The only disadvantage is a continual build-up of non-specified tramp elements like copper, boron and calcium. The AOD process allows precise gas manipulation to achieve the desired result and refines stainless steel by gradually replacing oxygen by means of blowing argon through the molten metal to eliminate impurities.
The American Society for Testing and Materials (ASTM) specification shows the chemical composition of any alloy in ranges with a minimum and maximum allowable limit to meet the requirements for the specific alloy. For example, the chemical composition for 316L stainless is as follows.
| 316L | Chromium | Nickel | Molybdenum | Carbon | Iron |
| Minimum | 16% | 10% | 2% | ||
| Maximum | 18% | 14% | 3% | 0.035% | Balance |
Today, when alloying 316L stainless steel the AOD process allows precise control of alloying elements, enabling the mills to make a product to an exact chemical composition. This also allows the elements to be controlled to the minimum range allowed for the specification. Compared to decades past when alloying 316L, the amounts of alloying elements were added with little control and often pushed or exceeded the upper limits of the maximum requirements. The resulting steel was a product with corrosion resistant properties superior to 316L stainless steel that is manufactured by using today’s methods. Today we see melts of steel meet the requirements of the specification on the low end, resulting in the overall mean corrosion resistance of the material trending downward. If a higher alloyed, but within-grade 316L composition is desired, it typically requires a special order of a full heat of material. Due to the cost or purchasing a complete melt, it is often more practical to specify a more corrosion resistant grade such as 904L, duplex stainless steel or a 6% Mo grade to obtain small quantities than to special order an enhanced 316L composition.
Determining the corrosion resistance of any alloy is always a challenging task. Varying service environments, aggressive cleaning and sterilization practices, and even multiple product forms of materials used in equipment fabrication can have a negative impact on corrosion resistance of materials. Because of these ever-changing conditions, the best corrosion data available is often the service history of the system itself. When choosing the correct materials of construction, it is recommended that a qualified Materials Engineer be consulted for evaluating the solutions, compounds and operating conditions the system will be exposed to. The most widely accepted materials of construction beyond 316L stainless steel in high purity and sanitary applications are the super-austenitic, nickel, and duplex alloys. These alloys can vary in their chemical make-up resulting in different levels of performance in certain corrosive or acidic environments. Table MM-2.1-1 in the current edition of the ASME BPE Standard identifies materials acceptable for use in the Biopharmaceutical industries that have been proven they can meet the requirements of welding and surface finishes listed within the Standard. Of these materials listed, this paper is going focus on Type 316L austenitic, superaustenitic stainless steels 904L, Ultra6XN, AL-6XN® and nickel alloys C-22® and Alloy 22.
ASTM Composition of Wrought Steels
| UNS | Alloy | EN | C | Mn* | Cr | Ni | Mo | N* | Cu | PREN |
| S31603 | 316L | 1.4404 | 0.030 | 2.00 | 16.00-18.00 | 10.00-14.00 | 2.00-3.00 | 0.10 | … | 24 |
| N08904 | 904L | 1.4539 | 0.02 | 2.00 | 19.0-23.0 | 23.9-28.0 | 4.0-5.0 | – | 1.0-2.0 | 36 |
| N08367 N08926 | Ultra 6xn | 1.4529 | 0.02 | 2.00 | 19.0-21.0 | 24.0-26.0 | 6.0-7.0 | 0.15-0.25 | 0.75 | 45 |
| AL-6XN® | AL-6XN® | – | 0.03 | 2.00 | 20.0-22.0 | 23.5-25.5 | 6.0-7.0 | 0.18-0.25 | 0.75 | 45.2 |
| N06022 | C-22® | 2.4602 | 0.01 | 22 | 56 | 13 | 0.5 | 68 | ||
| N06022 | Alloy 22 | 2.4602 | 0.015 | 22 | 56 | 13 | 0.5 | 68 |
*Maximum
Note: Sulfur is limited to 0.030 max and Phosphorous to 0.045
When comparing alloys for corrosive environments, the most important elements of the materials chemistry for corrosion resistance is Chromium, Molybdenum, Nickel and Iron. None of these listed elements alone are magical in preventing corrosion but alloyed correctly and manufactured properly, can improve corrosion resistance and the life expectancy of a high purity system.
- Chromium – Cr is a key component of stainless steel that accounts for its passive nature. Chromium significantly improves corrosion resistance when the composition contains a minimum of 10.5%. When at or above these levels, an adherent and insoluble surface film, known as the passive film, is instantaneously formed that prevents diffusion of oxygen into the surface thus prevents oxidation of the iron in 316L stainless steel. Chromium is also the weak link in stainless steel when in contact with chlorides by reacting with the chromium oxide in the passive layer to form chromium chloride, which is very soluble. This leaves a layer of iron and iron-nickel on the surface, an active film which will allow the stainless steel to corrode and the metal to be consumed.
- Molybdenum – Mo increases the resistance to localized corrosion in the forms of pitting and crevice corrosion. The higher the molybdenum content, the better the corrosion resistance to higher chloride levels by enhancing the passive film, making it stronger and helping it to re-form quickly if it is disrupted by chlorides.
- Nickel – Ni is an alloying element critical to stainless steels and results in the formation of the austenitic structure that increases strength, impact strength and toughness, while also improving resistance to oxidization and corrosion. It also increases toughness at low “cryogenic” temperatures. Nickel has no direct impact in the formation of the passive layer, but it does offer improvement in resistance to acid attack.
Another alloying element that has a positive impact and found in 316L, Ultra 6XN and AL-6XN® is Nitrogen-N, which increases the austenitic stability of stainless steels and improves yield strengths in low carbon grades of steel containing less than 0.03%. It can also enhance resistance to localized pitting and intergranular corrosion.
A guide to the corrosion resistance of alloy can be found in the calculation of its Pitting Resistance Equivalency Number (PREN). The chemical composition of the alloy along with this formula (Cr + 3.3Mo + 16N=PREN) will result in a number ranking the alloy. The higher the number, the more resistant the alloy is to localized corrosion. PREN’s can be found in the materials table above.
Those alloys containing 6% molybdenum content may require special fabrication methods beyond what is generally found in 316L stainless steel systems. However, they are common place and manufacturing practices are available to guide fabricators and suppliers. All the alloys listed in the table above are available in common sizes found in most sanitary designs and product forms such as tubing, fittings and valves.
For information regarding pricing and specifics of fabrication please contact the author.
AL-6XN® in a registered trademark of Allegheny Technologies Inc.
C-22® is a registered trademark of Haynes International Inc.
About the Author:
Ken Kimbrel is Product Manager – Special Alloys for VNE Corporation in Janesville, WI. He is responsible for specialty alloy sales, market planning, process and material evaluation in corrosive environments. He attended Tulsa Comm
Ken Kimbrel
unity College and has an extensive background in engineering, equipment manufacturing, and is a NACE International Board-Certified Corrosion Technician. His expertise includes corrosion evaluation, material selection, surface finish evaluation, and rouge remediation.
Ken is the current Chair of the ASME BPE. He has served as inaugural Chair of Subcommittee on Metallic Materials and as past Chair of the Surface Finish Subcommittee. He is a member of the Subcommittees on Accreditation, the Standards committee, Executive committee and author of several technical papers.
He is a member of the International Society for Pharmaceutical Engineering (ISPE), ASM International (ASM), the International Metallographic Society (IMS), the National Association of Corrosion Engineers (NACE).
Contact information:
E-mail: kkimbrel@vnecorp.com | Ph: 800-356-1111 | Cell: 417-827-2526
Universal Twin Screw Pump- The “Can-Do” Twin Screw
In today’s post, we wanted to focus on one Waukesha Cherry Burrell’s newest products- the Universal Twin Screw pump.
Twin screw pump technology has been around a long time, but only recently has this technology been used in sanitary pump applications. When properly applied, twin screw technology can offer compelling advantages over other types of sanitary PD pumps.
One of the first differences you’ll notice between twin screw pumps and traditional rotary lobe pumps is the axial motion twin screw pumps use to convey product through the screws. This axial type movement of product allows operation with low NPSH and virtually pulse free pumping. And by adjusting the pitch of the pump screws, twin screw pumps enable very low shear pumping and can handle solids much more gently than rotary lobe pumps
The axial pumping motion of the Waukesha Universal Twin Screw pump also enables the pumps to be run at much higher speeds- up to 3500 RPM. Higher speeds mean greater turndown, giving users the ability to use the Waukesh
The Universal Twin Screw Pump
a Universal Twin Screw pump as both a product AND CIP pump. Twin screw pumps can also handle large amounts of entrained air, making them ideal for pumping out of tanks following cleaning.
Users of Waukesha Cherry Burrell brand pumps have for years benefited from the reliability and consistency their products are known for. The Universal Twin Screw pump is no exception and runs with the same reliability Waukesha is known for, quickly making it the Universal Twin Screw the “Can Do” Twin Screw.
The Universal Twin Screw takes the reliability of twin screw pumping technology to the next level by incorporating non-galling Alloy 88 screws to run with tighter tolerances and through incidental contact by reducing the risk of damage in the event screws make contact with the pump body. Large diameter 17-4 shafts have greater strength than standard stainless steel shafts, helping to reduce vibration and extend seal life. And the 316L product contact body and cover and 304SS gear case allow the Universal Twin Screw to perform in even the most demanding conditions.
One common complaint we’ve heard at Holland about twin screw pumps over the years has been high cost of spares and low levels of support once the pumps have been deployed. Waukesha twin screw pumps are manufactured in Delevan, WI and available through the same industry leading distribution channels that have serviced and supported the high purity process industry for years. Our sales engineers have extensive twin screw experience with most brands of twin screw technology and Factory Certified Holland Service technicians are ready to service any of your twin screw pump needs.
So if you have questions about twin screw pumps or any sanitary positive displacement pump, contact a Holland Sales Engineer today.
The Universal Pump Base
Amazon has ruined the world for everyone.
Hear us out. Amazon is spoiling everyone. Thanks to Prime and other popular online web services, we want everything yesterday.
For years, Holland has focused on delivering to our customers custom solutions for their complex process problems. Your one stop shop for everything sanitary process. Our products are often made to order- sometimes making it hard to deliver yesterday.
Increasingly, the feedback we’re getting from our customers is their desire for standardization and quick turnaround. Incredible value, without sacrificing quality.
The Universal Pump Base
Some might call it, “Sanitary Process Prime”.
Well, after years of development, we are excited to announce the first of a number of steps we’re taking to deliver Sanitary Process Prime- the Universal Pump Base.
At Holland, we’re a lot of things. We build sanitary process skids, fabricate custom flow components, and even crimp hoses. But at the end of the day, we’re an industrial distribution company and a Waukesha Pump dealer. Holland Sales Engineers have been expertly deploying Waukesha’s industry leading line of positive displacement pumps- the Universal 1, 2, and now 3, for years.
After all these years, one of the things we figured out is that every Universal Pump needs a base. But the base is usually the great contributor to lead time. Well, after careful analysis of the hundreds of custom pump/base/drive assemblies we’ve built, we found we could offer a Universal style of base that would cover 70-80% sanitary PD pump applications.
The goal of the Universal Pump Base program is simple- to offer round and square tube pump bases for the U1, U2, and U3 Models 6, 15, 18, 30, 60, and 130 with incredibly quick lead times and tremendous value without sacrificing industry-renowned Holland Quality.
The Universal Pump base is available in both round and square tube designs. Fabricated at our state-of-the-art hygienic fabrication facility, both styles of base are fabricated from 304 Stainless Steel and utilize Holland designed sanitary adjustable feet and all hygienic welds. The standard design is compatible with Sterling Electric 0402A and 0602A gear boxes in TEFC, white washdown, and stainless steel. Bases can even be equipped with an upright for a Lenze AC Tech variable frequency drive, installed and wired by Holland Pump Technicians.
And best of all, with the combination of a Universal Pump Base, our on-hand Waukesha PD pump inventory, and a strategic partnership with Sterling Electric, Holland can now deliver these complete sanitary pump/base/drive assemblies- sized and applied specific to your application- in as little as five days.
For more information on all of our sanitary pump and base offerings, contact a Holland Sales Engineer today.
Waukesha Universal 2 Sanitary PD Pumps
Product Focus- The Universal 3 Positive Displacement Pump
In today’s post, we wanted to focus on one Waukesha Cherry Burrell’s newest products- the Universal 3 External Circumferential Piston (ECP) pump.
Rotary lobe or External Circumferential Piston pumps have been around for years. And for almost all of those years, Waukesha Cherry-Burrell, an SPX company, has been the industry leader in sanitary ECP Pumps. Starting with the Universal 1, and furthered with the Universal 2 series of PD pump, Waukesha ECP pumps move fluid by drawing it in to the pump head and through two counter-rotating pistons. These pistons, or rotors, sweep along the outside of the pump body and turn at constant velocity.
The shape of the rotors and cavities not only moves the fluid, but deliver a constant volume per unit time for any rotor position. And because all Waukesha pumps use a non-galling Alloy 88 rotor, all Waukesha Universal Pumps have exceptionally tight tolerances and near perfect efficiency with fluids over ~300 CPS.
If you’ve been following our blog, you know we use Waukesha PD pumps across almost every sanitary pumping application. Their simple and robust design allows them to handle both low and high viscosity fluids and delivery metered flow at pressures of up to 500 PSI. They run across a range of speeds, enabling low shear pumping and handling of particulate. The Universal 1 pumps can be easily taken apart and cleaned out of place, while the Universal 2 series of pump is designed to be cleaned in place.
But that’s enough about the Universal 1 and 2 pump. Let’s talk about the latest and greatest- the Universal 3 pump. Optimized for the most grueling of sanitary positive displacement pump applications, the Universal 3 features a front loading seal desig
n making repair and maintenance a breeze. Have you ever tried to pull the body off a U2 220 that’s connected in line to inspect the seal for damage? It’s a pain in the ass- to say the least.
The new Universal 3 also combines a few other features of the legacy U1 and U2. Like the U2, the Universal 3 is CIP capable standard. The pump body has internal flats that allow it to free drain when the ports are oriented in the vertical. A new cover design also enables free draining on the horizontal or vertical port positions.
Also like the Universal 2, the Universal 3 comes standard with a single mechanical seal with options to convert to a double mechanical seal with flush. And like the Universal 1, the Universal 3 is available with both O ring and lip seals as well, making it ideal for difficult chocolate or confectionary applications.
And while the Universal 3 does come from the same core platform as the U1 and U2, it also integrates years of product research and development, making it the most robust PD pump ever built. The U3 can handle differential pressures of up to 500 PSI and is rated for fluid temperatures up to 300 F. The U3, similar to the U2, has a special rotor nut designed for extended service without loosening. The new pump shafts are shorter and user larger diameter 17-4PH, reducing overhung loads and improving shaft alignment. This decreases seal and bearing wear, extending pump life. The Universal 3 also comes standard with a 304SS gear case.
Dimensionally, the U3 is almost identical to the U1 and U2, allowing drop in replacement of current pumps and cover the same hydraulic range as the U1 and U2. The new U3 is compatible with Holland’s Universal Pump base and Holland Sales Engineers can expertly apply and deliver a U3 for you application in as little as 10 days.
So if you have questions about the new U3 or any sanitary ECP pump, contact a Holland Sales Engineer today.
Holland Applied Technologies- An Overview
At Holland, we focus on Quality in everything we do. Check out our new Overview Video to see what Holland Quality means.
BPOG Best Practice Guidelines for Mitigating Risk used in Biopharmaceutical Manufacturing
Recently, BPOG (Biophorum Operations Group) has published a guide that relates to mitigating risk in bio manufacturing processes when using single use systems components. A key aspect of the risk mitigation strategy is to consider the potential for chemical entities to migrate from the single use component material into the drug product. Suppliers could aid drug manufacturers with their risk mitigation strategies by generating extractables data on their single use materials. Extractables are typically ‘worst case’ indicators of potential leachables and provide a drug manufacturer with useful information on how to approach future leachables studies.
Key definitions to understand are listed below:
Extractables chemical entities that are able to be extracted from a component of a process system into a solvent under controlled conditions which are usually more aggressive than the normal operating conditions
Leachable’s chemical entities which come from single-use system components that migrate into the drug product during normal use. The single use system consumable qualification process must demonstrate that processing components do not impact the quality of the drug product.
It is important to understand that the product quality should be maintained throughout the drug product lifecycle to ensure that the attributes deemed important to the quality of the drug product are consistent with those evaluated during clinical studies.
One aspect detailed by BPOG and other industry bodies is how to perform risk evaluation. Risk evaluation is based on assessing the risk to patient safety, product impact manufacturing and regulatory approval. The regulations for drug manufacturers specifically detail that the equipment used in manufacturing of the drug substance shall be constructed so that the surfaces that contact the process material or drug product shall not be, reactive, additive or absorptive.
Risk assessment can be focused on either testing of every single use system component or by taking a risk-based approach where only critical single use system components are tested. The approach taken can be determined by considering the following key attributes
- Distance of the single use component to the final drug product or API
- Process temperature
- Process time
- Process fluid interaction
- Dilution effects
If you have additional questions about extractables, leachables, or any single use components, contact a Holland Sales Engineer today.
*A Special thanks to Sade Mokuolu @ WMFTG BioPure for her help in putting this blog together
What Sanitary Gasket Material Should I Use? Check out our Chemical Compatibility Guide!
With so many options available for elastomers it can be hard to make sure you are selecting the one best suited for your application. This post is going to go through a few key questions to point you in the right direction.
Let’s start by asking a few important questions about your application:
- What temperature is your process running at?
- How are you cleaning your system?
- What are you trying to seal?
Once we figure out the answers to those questions, we can start by looking at the three most common elastomers used in the high purity process industry- FKM, Buna, and EPDM. We’re going to leave PTFE out because it isn’t an elastomer- it’s a plastic.
FKM and EPDM are able to handle high temperatures well, and with an upper operating temperature of up to 400 degrees Fahrenheit they are the clear choice for high temperature applications. EPDM is great with steam, but does not mix well with oils. And FKM doesn’t perform as hot at low temperatures, with a lower operating temp of only 5 degrees.
Accordingly, if you are planning on either SIP or CIP, you’ll want to go with FKM or EPDM. SIP uses steam to heat the process line up to at least 250 degrees Fahrenheit, which will cause some strain on your elastomers. If you are going to be running steam frequently through the process line then FKM or EPDM are a good choice for you due to its resiliency against steam and its ability to tolerate the temperature.
For CIP applications, all three elastomers provide good resistance to both acidic and caustic solutions commonly used in CIP procedures although Buna does not tolerate concentrated acids very well.
Before installing a new component you should always make sure that it is chemically compatible with your process fluid. In general, FKM is fairly inert compared to both Buna and EPDM and is well suited to most applications. But a chemical compatibility chart is available here to check your specific application.
By selecting the proper elastomer you may be able to stretch out the time between replacements.When it is time to replace them or if you have any questions please contact a Holland Sales Engineer.
At Holland, we’re no strangers to sanitary batching systems. One of the most common customer challenges we’re asked to solve is a simple batching application. Our customers turn to Holland for a one stop, robust solution that is cost effective and quick to implement. Previous posts have focused on batching systems that are volume based solutions- systems that incorporate a flow meter to control a process. This post will instead focus on weight addition systems and the different system solutions available.
So let’s say you have a recipe for a product you make all the time. A recipe is, by definition, a set of instructions for obtaining a desired outcome. Every recipe has a several ingredients. How we choose to add those ingredients to a receiving vessel is a critical question that must be addressed early in the process design. One way to do it is with a flow meter used to volumetrically measure each ingredient introduced. While this may work well if you only have one ingredient or may be just metering off from a bulk tank, a volumetric system does have its drawbacks. For one, accuracy is limited to accuracy of the flow meter used. In some cases, the meter used is a turbine meter. These can have accuracies that deviate as much as 5%.
Even if the accuracy of your flow meter is sufficient for your application, many recipes call for a mass of product to be added- pounds, kilograms, etc, NOT a volume. To do this, best practice would indicate that we take a direct weight NOT volumetric measurement. When using a volume to add mass, you depend on a density based conversion and depending on processing conditions, fluid density can vary. The only way to do take a direct mass measurement is with a Coriolis meter, which often run well into the tens of thousands of dollars, depending on line size. Can you imagine if you have multiple ingredients, necessitating multiple coriolis meters? You also can’t pass solids or dry products through a flowmeter.
As an alternative to volume based batching systems, let’s consider a weight based alternative. With a weight based system, we use either a floor scale or load cells to measure the weight of either the receiving or dispensing container (a future post will take a closer look at weight by addition vs. weight by loss systems).
For this post, we’ll assume that the receiving vessel is on load cells. With the receiving vessel on load cells, we can add multiple ingredients, liquid or dry, while only measuring one process. This greatly reduces the instrumentation cost of a system. Using a controller, either a PLC or something even simpler, like a Mettler Toledo IND690, valves can be opened and closed, pumps start and stopped once volumes are added. Controllers like the IND690 allow for recipe programming and storage and also have a digital display with tare functions to allow for manual addition if need be.
At Holland, we’re able to take you all the way through system development. We usually start by working with a client to either design and fabricate a batching vessel, or retrofit an existing vessel to accommodate load cells. We then help identify and install auxiliary equipment that is very important AFTER ingredients are batched in- components like mixers, RTDs, and tank outlet valves. Once we identify what you want to measure and how you want to measure it, we can start working on HOW we’re going to add ingredients. This can be by Waukesha PD pump, Masterflex peristaltic pump, or Quattroflow Quaternary diaphragm pump. We can also supply the proper ITT diaphragm or Waukesha seat valve to control flow in. Once that is done, we can work with you to size and select an appropriate floor scale or load cells. Coupled with the right control system, we have a fully functioning batching system, capable of adding a variety of different ingredients and storing several different recipes. So if you have any questions about your next sanitary batching application, contact a Holland Sales Engineer today.
What are Weld Maps and Weld Logs?
If you haven’t figured it out yet, at Holland Applied Technologies, we are in the sanitary component and custom systems market and cater exclusively to the high purity process industry. In the high purity process industry, specifically the biopharmaceutical industry, documentation requirements are a key distinguisher between people who play in the industry and those that live in it. One of the most critical processes our customers trust us with is welding of material to create the fluid transfer paths that carry their products. Weld inspection and logging has been and will always be a key part of any Quality Assurance program. But because of the requirements of the US Food and Drug Administration and guidelines outlined by the American Society of Mechanical Engineers Bioprocessing Equipment Standard (ASME BPE), the weld documentation our customers ask us to provide is even more extensive. This post will focus on proper weld documentation specifically weld logs and weld maps- what they are and what information they provide.
Let’s start with the weld map. Weld maps are isometric drawings of the assembly to be welded showing the location with each weld, each weld having its own unique identifying number. They also contain a bill of material with the part number of each component used in making the assembly. After each weld is completed, it is labeled with a weld number (usually pin stamped on the part) that corresponds to a number on the isometric drawing of the part. When the isometric drawing is reviewed during validation, a third party can use the weld map to quickly identify where on the process piping the weld was performed and then refer to the weld log to ascertain the data discussed above.
Weld logs contain the data specific to each individual weld. Normally a weld log sheet would contain all of the welding information for the welds on a specific isometric drawing. At the top of any weld log, you’ll usually find client specific project specific information, i.e. project number, job number, etc. You’ll also find the drawing number of for the isometric drawing that the log matches up with. You’ll also see a section for gas lot number of the Argonne gas used for the weld purge as well a block with the signature of the welder who is doing the work.
For our weld logs, the main body of the document has 9 columns for the weld to complete and 3 for the weld inspector. For each weld, the welding technician first enters the weld number, the date, what piece of welding equipment is being used and which weld procedure is being used. All of our welding personnel are qualified to specific ASME Section IX weld procedures. They then enter the heat number for each of the two components to be welded, the size of the tubes being welded and their own initials.
The rest of each line on the weld log is used by the weld inspector. Each weld is visually inspected by a qualified weld inspector using a boroscope to examine the weld ID. After inspection he completes the log for that individual weld as to whether it had been boroscoped, did it pass the visual boroscope examination, the inspectors’ signature and the date.
Typical Holland Weld Log
Once this process is completed, these documents, as well as the corresponding material test reports of the components used in the assembly, become part of the turn over package that ships with the system. Properly executed, you now have a comprehensive package identifying each weld, who made the weld, what components went into the weld and the corresponding material certs for each one of the components.
As we wrap this blog up, let’s not forget why all of this documentation is important. The systems we fabricate at Holland Applied Technologies are used by our customers to manufacture drug products we literally inject into our bodies. And before the drug ever gets made, the system used to make it needs to be validated. Governing bodies like the US Food and Drug administration use the data provided in these logs and maps to approve the manufacturer and manufacturing facility, protecting public health and giving consumers the peace of mind that the medicines they are taking are made on systems and in facilities that comply with current best practices. So if after reading this blog, you have any questions about high purity process welding or documentation requirements, contact a Holland Sales Engineer today.
What are the NEC Requirements for Conduit Fittings in Explosion Proof Applications?
4 Cable Seal Off
At Holland, we encounter many electrical system design challenges. Between large biopharmaceutical and food modules, smaller sanitary process skids, pump carts with VFD’s, etc., there are many chances to learn. Recently we had an interesting situation that required us to modify our design to meet a portion of the NEC standard for Hazardous Classified location equipment.
Section 500 of NFPA 70: National Electric Code defines the requirements for building equipment in Hazardous Locations. The standard is broken down into three “Classes”-Class 1 deals with flammable gases and liquids, Class 2 deals with combustible dusts, and Class 3 deals with ignitable fibers. For our purposes, we are concerned with Class 1. This classification defines (among many other things) the requirements for electrical enclosures (which must be explosion proof) as well as the conduit lines that carry electrical cables back to these enclosures.
The requirement of the standard is that all conduit lines must have a seal off located within 18 inches of the purged panel enclosure. Seal offs are (as there name implies) a barrier that is filled with a compound that “provides a seal against the passage of gas or vapors through the seal fitting”, and therefore into the enclosure potentially leading to a dangerous situation. Further, the standard requires that only 25% of the cross sectional area of the sealed fitting can be used up by the conductor wiring. Note that this is significantly less that the 40% allowable area that can be used in all the other fittings in the conduit assembly.
In our case, we realized during field installation that although we met the general 40% requirement, we did not meet the more stringent requirement in the seal off. This situation presented a few options that we had to think through. The first option was to increase the size of the seal off. The standard allows for a larger trade size seal when required to meet this requirement. Unfortunately, Crous-Hinds (as well as Gibson and Calbrite) doesn’t offer a seal off in stainless steel that is larger than 1 inch. There are other options for larger seal offs in other materials of construction (Robroy makes a PVS coated metal conduit (Plasti-Bond) in much larger sizes as well as EYX in galvanized iron), but the specification on this job required stainless steel.
Option two was to reduce the size of the cables. The initial choice was a 3 conductor + ground 18 gauge wire. There are some nice advantages to running multiple conductors, primarily being that it gives more flexibility down the road with device choices (think limit switches, more instrumentation, troubleshooting, etc.). However, in this case we needed to figure how to make this work. We opted to use a 2 conductor with 18 gauge wire, reducing the wire size by more than 30%. This choice met the requirement for cross sectional area of the seal off, effectively getting us in “just under the wire” (ok, I have been waiting to use that) to meet the standard.
Electrical design is a big part of our work at Holland. Hopefully this post will give you some ideas if you run into issues with seal offs and related Class 1 work. Contact one of our Holland Sales Engineers a call if we can help you with a project you are working on.