Using metal hose and expansion joints in CIP systems

By: Frank Caprio | On: April 2, 2019

Cleaning-in-place, or CIP, is a method used to clean piping systems and the attached equipment without the need to take the system apart. It is commonly used in the food processing, pharmaceutical, and cosmetic industries, which must meet very stringent cleanliness requirements. The flexible piping components used in these systems must also be able to withstand the harsh conditions required for effective cleaning in place programs. Here are some things to consider when specifying hoses or expansion joints.

What is “clean”?

Different industries require different levels of cleanliness, depending on the media being conveyed and its intended destination. We recently published a blog post on oxygen service, which noted that industrial oxygen service has much different cleanliness requirements than medical-grade oxygen. The same is true for other gases, chemicals, and food products. An important distinction that must be understood is the difference between “clean”, “sanitary” and “sterile”. Although they are related terms, they actually have very different meanings. According to Ultronics USA (a maker of disinfectant and cleaning systems):

  • Cleaning is the mechanical removal of visible surface contaminants, soils, etc., usually with soap, water, and enzymatic detergents.
  • Disinfectants are products that are applied to inanimate surfaces or objects to kill many or all microorganisms except resistant bacterial spores…Sanitizers are products that disinfect.
  • Sterilization is an extreme physical or chemical process that eliminates all forms of microbial life, including transmissible agents (such as fungi, bacteria, viruses, and all bacterial spore forms).

While chemicals are often used to disinfect or sterilize equipment, steam is also very effective. Autoclaves are an example where steam is used to sterilize medical equipment, combining heat and pressure to kill any pathogens. However, sterilization does not necessarily remove surface contaminants, so a cleaning process is usually performed before sanitization or sterilization. Radiation is another sterilization method, although it is not practical for most applications. Obviously, it is important to make sure the hose or expansion joint can be cleaned to the proper requirement or standard.

Industrial CIP systemscleaning in place metal hoses and expansion joints

Many industrial processes require that the system is cleaned and sanitized to remove any impurities which could negatively affect the desired chemical reactions. CIP is a preferred cleaning process, as it efficiently removes contaminants at a competitive cost. The CIP process typically utilizes a water rinse, then a caustic-based cleaning cycle, followed by an acid bath and another rinsing cycle. Steam may also be used as part of the cleaning process. Flexible metal hoses and expansion joints are key components in CIP systems, as they offer excellent resistance to both alkaline and acidic environments and the extreme temperatures common to these systems.

The ethanol industry is a great example of this. While ethanol can be found in alcoholic beverages, a large industry has evolved where biorefineries produce ethanol for use as a renewable fuel. While the ethanol fermentation and distillation methods are similar to those used by the beverage industry, the end product is not intended for human consumption; in fact it is mixed with just enough “denaturants” (e.g. gasoline or methanol) to make it unfit for drinking. Because of this, the equipment must be sanitized, but not to levels required for beverage manufacturing.

During fermentation, calcium oxalate precipitate can form, which is better known as “beer stone”. This scale is primarily produced through a reaction between alkaline cleaning agents, minerals present in the water, and proteins found in the fermenting mash. Once this scale has formed, it can be extremely difficult (and expensive!) to remove, so a thorough cleaning protocol is needed in order to prevent scale buildup. In larger biorefineries, metal expansion joints are preferred for all the reasons listed above, and are commonly found on piping connections to large process vessels. These expansion joints often include internal liners to help prevent any beer stone from forming and collecting in the convolutions. Unfortunately, the liner also tends to isolate the convolutions from effective cleaning during CIP operations.

When Hose Master’s engineers were presented with this problem, we designed a special bellows that could handle the service requirements without the need for a liner, thus improving the efficacy of the cleaning process and saving the customer lots of time, money and aggravation. Even if non-metallic hoses or expansion joints are used during normal operating conditions, they are often replaced by flexible metal products during CIP operations, and cleaned using gentler methods.

Alloy selection is critically important, to ensure resistance to corrosive chemicals and temperature extremes. As always, if your customer needs assistance selecting the best alloy for their application, make sure to get the name of the chemicals being used as well as their temperature and concentration at which they are being transferred. We can then consult various resources to select the most cost-effective alloy for the application. Contact us today for innovative solutions to today’s toughest applications.


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