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Overview

Southern Metal Processing Co. Inc. has been providing contracted cleaning service to the Polymer, Chemical and Petrochemical Industries for 35 years. Our facilities have operated 24 hours per day, seven days a week 365 days a year continuously since 1973. Our day supervision as well as shift supervisors are accustomed to daily communications with customers concerning pickup, delivery and status of all work. If required, one of our vehicles can be dispatched within hours to pick up or deliver equipment critical to the day-to-day operations of our customers. We have installed and maintain backup power generation in the event of severe weather conditions.

We pride ourselves in the use of cleaning processes specifically tailored to provide optimum economics to accomplish the desired result while being aware of the criticality of its effects on performance, appearance, longevity and timely availability of equipment. Through this attention to detail and awareness of potential effects on issues such as filter media integrity, performance and cycle life, SMP is able to provide its customers with repeatable long term economic benefits.

Once an opportunity is realized for us to provide one or possibly multiple services, we first look at the chemistry of the contaminant and/or residual material remaining. From this point, we look at the materials of construction of the components, method of fabrication and any critical details such as sealing surfaces, bearing surfaces, thermal limitations, etc. before a process is developed or implemented.

Some of our more frequently used processes are described in detail in later sections. While these or a slight modification is typically the most expedient or lowest initial cost due to reduced development or equipment and/or chemical availability, it should be understood that any specific or special requirements of a given cleaning challenge will be evaluated and implemented as needed. We are willing to develop new techniques and practices as required to meet a customer’s needs or specific equipment requirements.



Abrasive Cleaning

Abrasive cleaning processes are used when chemical or thermal processes are not affective in removal of contaminant, economics require a low labor and/or chemical/utility contribution or favorable secondary benefits arise from the process. In such cases, Southern Metal Processing Co. Inc. has several alternative automated processes and equipment available to effect this cleaning requirement. Densities, particle sizes, metallurgies and impingement velocities can be selected to yield the most affective and economic solution to the cleaning requirement. Call or email us to discuss your specific needs.

Solvent Cleaning

Solvent processes are based on the premise that “like dissolves like”. As such, solvents are most effective in dissolving and removing organic materials, such as polymers, oils and grease, or other soluble contaminants.

This cleaning approach is most effective when removal of contaminant is required from within the interstices of fine metal filter media such as stainless steel sintered fiber, sintered powder or woven wire mesh to facilitate the reuse of these expensive materials. It has the added benefit of being the least aggressive toward attack on the extremely fine fiber or particle diameters that are used in the construction of these mediums. It is also frequently the process of choice in cleaning of delicate metal components and fabrications where distortion is possible with the use of high temperatures or damage to surfaces possible from abrasion seen in other processes. Southern Metal Processing Co. Inc. offers a variety of existing solvent processes and can work with its customers to develop new ones provided the economics are justified. Call or email us to discuss your specific needs.

Pyrolysis

Pyrolysis cleaning is often referred to as a “Burn Off” process. In this approach, a part is placed in a high temperature oven (e.g. 750 OF to 850 OF) and heated to the point where the contaminant breaks down. The oxygen level is reduced to 6 % or less during the process.

This cleaning approach is often the only choice in removal of high molecular weight polyolefins such as polypropylene. It is very effective and economical in removal of coatings and epoxies from paint racks, die blocks etc. Manual cleaning of surfaces is usually a secondary requirement. Call or email us to discuss your specific needs.

Molten Salt

Molten salt bath treatment of metallic components (i.e. filters, dies, spinnerettes, racks, tooling, etc.) for the removal of non-solvent friendly polymers, paints, powder coatings, epoxies and fluorinated/chlorinated polymers is a safe economical technology. In this approach, a part is placed in a salt bath (i.e. salts specifically formulated to protect metal components) at just above the salts melting point and then heated to 725 OF to 850 OF. The specific temperature depends on the characteristics of the contaminant and the thermal limits of parts to be cleaned. As a result of the density difference between molten salt and the contaminant in conjunction with the absence of free oxygen, the removal and/or decomposition of the contaminant is easily accomplished.

Polymers either melt and separate due to density differences or are converted to their decomposition by-products, typically CO/CO2 and H2O. The later reaction is the primary mechanism for paints, epoxies, powder coatings and other high molecular weight or cross linked contaminants, including coke/graphite/carbon. Manual cleaning of surfaces or subsequent chemical baths followed by ultrasonics are usually a secondary requirement. Call or email us to discuss your specific needs.

Chemline

De-scaling, iron removal as well as numerous other inorganic contaminants or fouling materials can be removed via acid or caustic bath treatment followed by sufficient neutralization and flushing. These aqueous based solutions are tailored to the specific need for cleaning and safe handling of the metal components.

In addition, it is often necessary to further clean or rinse components after solvent, pyrolysis or salt bath cleaning to remove residual contaminants and ensure the complete removal of residual solvents or salts.

We manage a number of proprietary chemical treatment baths specifically developed through our years of experience and involvement in the cleaning industry for these purposes. The chemistry and process conditions of these baths are monitored and controlled to exacting standards to ensure adequate cleaning and the safe treatment of components. Call or email us to discuss your specific needs.

Ultrasonic

Ultrasonic cleaning is based on the process of cavitation, whereby ultrasonic waves are transmitted through a cleaning fluid, forming bubbles within low pressure areas and expanding until they enter a region of pressure high enough to cause their collapse. The energy created by these cavitations can effectively loosen and discharge many contaminants from a part’s surface.

Applied properly, ultrasonics is a cost-effective technology. However, it does have limitations based on size, shape and placement of parts in a bath, frequency of wavelength used as well as the fact that ultrasonic cleaning only loosens a contaminant. Subsequent spray or flushing procedures are required to provide the required mechanical transport of the particle away from or out of the part. As such, ultrasonic cleaning should only be considered as an augmentation step in any cleaning process. For optimum results and performance, the ultrasonic bath should be designed and configured for the specific part (i.e. size, geometry and construction) to be cleaned and the most effective frequency employed for the intended removal. Call or email us to discuss your specific needs.



Serializing & Baseline Testing

One of the most important issues related to a clean and re-use approach to filtration is validation of cleaned filters. The understanding of cleanliness as well as validating integrity are key factors. Through our years of operation and experience, Southern Metal Processing Co. Inc. has developed a variety of procedures for determining the relative cleanliness of a filter and developed processes that ensure consistent results. Testing and validation are equally important. In this regard, SMP has made significant efforts to understand and augment the understanding and validation of test criteria to ensure the integrity of an element.

Test results from each filter cleaned by Southern Metal Processing Co. Inc. is recorded into our database and maintained for its service life. In order to facilitate accurate records and tracking, every element must be given a unique serial number at the time of its first cleaning or testing. This number is etched into a non-critical surface of a filter along with specific customer identification code. This allows an element to be tracked relative to test data from first cleaning through to the end of its life. There is a minor charge to cover the labor required to conduct this work.

Since the life cycle and re-use criteria for a filter element is often based on the drop in bubble point and/or 10 LPM wet air flow, SMP feels that it is important to baseline test each element prior to any use. This allows us to establish the base data for the filter/media in its new condition and eliminate any testing bias between the supplier and SMP and/or highlight possible damage or specification deviations prior to it being put on line. If this is not practical, the test data obtained after the first cleaning cycle can be used as the baseline.

Test that are typically conducted are:

Bubble Point: The bubble point test is based on the fact that for a given fluid and pore size, with constant wetting, the pressure required to force an air bubble through the pore is inversely proportional to the size of pore diameter. In practice, this infers that the pore size of a filter can be established by wetting the element with a fluid and measuring the pressure at which the first bubble stream is emitted from the upper surface of the element when air is applied from the underside.

The point at which the first stream of bubbles emerges is the largest pore. Therefore, the bubble point value can be used to obtain a relative measure of the size of the single largest pore in a filter element.

The relationship is based on Poiseuille’s law which can be simplified to:

P=K/d
Where: K = an empirical constant dependent on the filter material, form and units of testing

Since this constant is essentially a capillary shape factor and is related to the material being tested as well as its form, it is easy to see why bubble point is typically only a relative comparison value for a given element and/or media.

10 LPM: The 10 LPM measurement is a continuation of the bubble point test. If after the bubble point is measured, the air flow is increased until the bubbles emerge from the second largest hole, then the third and so on until a point is reached where air bubbles appear over the entire surface of the element the open bubble point is reached. This open bubble is a relatively good measure of the mean pore size of an element provided there are no other restrictions or physical limitations (This is discussed in some length in a separate SMP technical paper.). Since this point can vary from filter to filter and media to media, SMP developed the 10 LPM (10 liters/min) test several years ago with one of its customers to establish a standard wet air flow test that could be used as a relative measure of the mean pore size of an element. This test provides a somewhat broader perspective of an elements mean pore size and ultimate integrity.

More Information: Bubble Point vs. 10LPM (.pdf file)



Consulting

One of Southern Metal Processing Co. Inc. objectives is to establish long term, all inclusive partnerships based on providing proactive contributions to our customer’s profits by maximizing the assets of the equipment we clean for them. In addition to providing the day-to-day contact and service required to maintain their equipment, it is becoming increasingly important to also provide the technical expertise to understand issues that develop or resolve performance issues. This latter development has come about as a result of many companies responding to market and economic pressure to survive. In an effort to reduce and control costs, companies are producing product with fewer people and less in-house knowledge. As a result, SMP has initiated a program to provide technical consulting services to our customers. This consulting service takes on a multitude of shapes ranging from complementary technical assistance for brief or relatively minor support to contracted technical support and analytical assistance to evaluate and resolve more complex issues. These more complex issues typically relate to improvements in technology or performance (e.g. product quality, operating costs or combination of both). The improvement in performance or costs does not usually come as a result of a specific manufacturer but rather the selection and/or optimization of a given manufacturers product for a specific application.

In this extension of our service offering, we provide to our customers an alternative to direct interaction with a multitude of equipment manufacturers. Typically a vendor supplies a product and charges an associated price aimed at maximizing his company’s profit. He attempts to justify these costs based on some sort of performance criteria while maximizing his profitability. A consultant supplies profit to the customer as his product. He offers a return on the customer’s investment and quantifies the benefits. In this regard, the consulting service is often paid for through reduced costs or improvements in performance. Give us a call to discuss your needs.