Cleaned and Bagged Piping: What It Is and Why It Matters

Why Does Contamination Matter in High-Purity Systems?

Consequences of contamination vary by specific industries and processes, but all may involve the same basic costs: production downtime, equipment repairs, faulty products that fail QA standards, safety incidents, etc. Some examples include:

• Pharmaceutical manufacturing (cGMP-regulated facilities): Contamination in process gas, lab air and compressed air systems can compromise the controlled environment these facilities are required to maintain.
• Battery manufacturing: Battery production processes can be sensitive to particulates, moisture and other contamination that may affect product consistency, performance and safety.
• Industrial gas distribution: Trace contamination can compromise purity ratings for the gases required for the chemistry of advanced manufacturing processes. Gases with high oxygen content are particularly vulnerable to fire and ignition hazards when particulates and flammable residues are present.
• Automotive and specialty paint applications: Contamination (especially silicone) in air and fluid lines can cause surface defects, overspray inconsistencies and costly rework.
• Semiconductor chip manufacturing: Substrates and layers of the chips are measured in nanometers, where any particulate debris can result in failure of the layering process.

Effective contamination control is therefore critical in applications where even trace particulates or residues can affect the finished product or process.

How Does Contamination Get Into Piping Systems?

Standard manufacturing processes for pipes, valves and fittings frequently leave particulates (metal shavings, dust or debris) and residues such as oils, greases, cutting fluids or other hydrocarbons (e.g., silicone) inside the products. Debris can clog microscopic ports/passages in precision equipment and affect product parameters (e.g., semiconductor wafers where layers are applied in nanometer thicknesses). Residues of volatile organic compounds (VOCs) can off-gas and react with sensitive chemical processes, while hydrocarbons can introduce ignition risks in oxygen-enriched environments. Silicone residues in trace amounts can cause defects in coatings, paint and other surface-sensitive applications.

In addition to manufacturing, storage of standard PVF components does not typically include provisions for sealing, so debris and other contaminants are often introduced as well.

Cleaned for Oxygen Service (CFOS) is an industry term for pipes, fittings and valves that have been cleaned to remove contaminants (to a specified level) and then individually bagged and sealed to maintain that cleanliness through storage and installation. These components may also be referred to as “cleaned and bagged”.

Why Is CFOS Important for Oxygen Service?

CFOS processes and standards were originally developed for applications where gas with enriched oxygen content (> 23.5%) was present, since the higher oxygen content promotes ignition and fire risks. Residues such as hydrocarbons and VOCs provide fuel, while particulates traveling in the gas flow can produce ignition sources via the heat from impact with the pipe walls. In normal oxygen-content environments, these effects are not sufficient to cause ignition, but the increased oxygen lowers those thresholds to a level where relatively small amounts can result in catastrophic failures. The CFOS processes ensure the removal of particulates and residues to eliminate these risks.

What Standards Apply to CFOS Cleaning?

CFOS processes are specifically established and governed by industry standards:

• ASTM G93 “Standard Guide for Cleanliness Levels and Cleaning Methods for Material and Equipment Used in Oxygen-Enriched Environments”: provides cleaning methods and cleanliness level requirements for oxygen service piping systems.
• CGA G-4.1 “Cleaning of Equipment for Oxygen Service”: provides details of cleaning methods for gaseous and liquid oxygen tanks, equipment and piping systems.
• MSS SP-138 “Quality Standard Practice of Oxygen Cleaning of Valves and Fittings”: provides methods for cleaning valves and fittings for oxygen service piping systems.
• ISO Cleanroom Classes: classification scale based on particles per cubic meter for cleanroom environments for cleaning and packaging of CFOS components.

While the listed standards above all refer to piping systems intended for oxygen service, the same cleaning processes are required to meet the purity levels for advanced manufacturing processes.

How Does Viega Prepare Cleaned and Bagged Components?

To provide solutions for both oxygen-enriched and high-purity piping systems, Viega has established processes to offer CFOS certification for Viega’s Copper and Stainless Steel fittings and 3-piece valve product lines: ProPress^® Copper, ProPress 316 Stainless Steel and MegaPress^® 304 Stainless Steel, 304 SS and 316 SS. Viega’s CFOS program takes the standard press fittings, valves and tubing through a specialized cleaning process, then individually bags them to maintain that cleanliness through installation.

• Cleaning and inspection procedures are performed in an ISO Class 8 cleanroom to remove contamination risks (particulates and residues) introduced during manufacturing and handling. Meets ASTM G93 Level “A” (less than 1mg/ft2 residues).
• Sealing elements are cleaned and lubricated with oxygen-safe, aerospace-grade lubricant approved for oxygen service.
• All components are purged and dried with high-purity nitrogen and individually bagged to maintain cleanliness through shipping and installation. Tubing products are capped instead of bagged.
• Products are labeled with cleaning standards and date of cleaning.

Viega’s CFOS program maintains the benefits of press technology like consistency and reliability while providing the cleanliness standards required for enriched-oxygen or high-purity applications.

Viega's Cleaned and Bagged offering is available for ProPress copper and stainless steel fittings and tubing, with MegaPress stainless steel and 3-piece valves rolling out in 2027.

Cleaned and Bagged fittings are not intended for medical gas systems (NFPA 99), FDA food-contact applications (3-A SSI) or pharmaceutical hygienic service and may not be used for these applications.